Rigid Pavement - Ohio Department of Transportation

JANUARY 1996

An Equal Opportunity Employer

MANUAL OF PROCEDURES

FOR

RIGID PAVEMENTPRACTICES

STATE OF OHIO DEPARTMENT OF TRANSPORTATION

TABLE OF CONTENTS

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Page

1.0 Introduction ............................................................................................................................................... 1

2.0 General ...................................................................................................................................................... 2

3.0 Inspection .................................................................................................................................................. 3

4.0 Mechanical Equipment .............................................................................................................................. 5

5.0 Batch Plants ............................................................................................................................................... 9

6.0 Subgrade .................................................................................................................................................. 10

7.0 Subbase .................................................................................................................................................... 11

8.0 Forms ....................................................................................................................................................... 13

9.0 Joints ........................................................................................................................................................ 15

10.0 Sawing and Forming Joints ..................................................................................................................... 20

11.0 Reinforcement ......................................................................................................................................... 24

12.0 Moisture and Mix Control ....................................................................................................................... 26

13.0 Placing and Speading .............................................................................................................................. 27

14.0 Operation of Transverse Finishing Machine ........................................................................................... 29

15.0 Operation of Combination Float Finisher ............................................................................................... 32

16.0 Slip Form Paving ..................................................................................................................................... 34

17.0 Field Checking ........................................................................................................................................ 37

18.0 Final Finishing ......................................................................................................................................... 40

19.0 Curing ...................................................................................................................................................... 43

20.0 Work to be Done Later ............................................................................................................................ 46

21.0 Hot Weather Construction ....................................................................................................................... 49

22.0 Cold Weather Construction ..................................................................................................................... 51

23.0 Job Control Testing and Sampling .......................................................................................................... 52

24.0 Pavement Cores ....................................................................................................................................... 54

25.0 Surface Smoothness ............................................................................................................................... 55

26.0 Measurement ........................................................................................................................................... 56

27.0 Concrete Pavement Repairs .................................................................................................................... 57

Check List for Inspection of Concrete Pavements .................................................................................. 62

Documentation Procedures ..................................................................................................................... 66

Glossary ................................................................................................................................................... 72

Index ........................................................................................................................................................ 77

Note: Any addendum to this manual to be inserted immediately following glossary.

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1.0 Introduction

Intent of Manual

This manual is intended to serve as a guide to the

Engineer and Inspector during the construction of

Portland cement concrete pavements. In order to

construct pavements meeting specification

requirements, personnel need to have a thorough

knowledge of the plans, specifications, proposal

notes, and standard drawings. This manual does not

in any manner alter or replace these governing

regulations, but is a supplement to them. The normal

sequence of inspection procedure is outlined to assist

project personnel in performing their duties.

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A Portland cement concrete pavement must be

constructed so that it will:

1. Provide a smooth riding surface satisfactory to

the traveling public.

2. Be durable when subjected to natural weathering

and chemicals used for snow and ice control.

3. Be capable of substaining the traffic which it is

intended to carry.

4. Be of sufficient skid resistance to eliminate

slippery conditions when wet.

While it may be that the quality of the riding

surface is the chief element of construction by which

the public either approves or condemns a pavement,

this element is of no greater importance than

durability and structural strength. All desirable

elements of a good pavement are a product of the

workmanship of the contractor and the engineering

and inspection personnel assigned to the work.

2.1 Construction, Culminationof Effort

The actual construction is the culmination of all

previous effort involving many ideas covering

research, traffic study, safety, construction materials

(including soils), design and finance. The entire

procedure is judged, however, by how well the

construction work is done and this responsibility falls

directly upon the contractor and his forces and upon

the Engineer and his Inspectors.

2.2 Every Step Important

Every step of construction, from the preparation of

the subgrade and subbase through curing and opening

to traffic, has a definite effect on the rideability,

durability and structural integrity of the finished

pavement. The text herein is designed to point out

and emphasize the purpose and importance of the

various stages of a concrete paving operation. The

composition of the mix and the elements of concrete

control are not discussed in detail because this phase

of the work is covered in the Manual of Procedures

for Concrete.

2.0 General

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3.0 Inspection

3.1 Assignment of Personnel

Prior to starting concreting operations, inspectors are

assigned to the project and instructed in their various

duties by the Engineer. Also, all necessary equipment

used on the project must be checked for conformance

to the requirements as set forth in the specifications

and approved by the Engineer before concreting may

begin.

3.2 Knowledge of Specifications

It should be emphasized that when a contract is

entered into it is thereby agreed that work shall be in

accordance with contract requirements. To enforce or

not enforce requirements is not a matter of opinion

but is expected by all concerned. Contract

requirements and plan details can be changed only as

a result of negotiation between the Contractor and the

Department and must be covered by a change order.

Obviously, all concerned with inspection and

supervision of construction should be familiar with

specification requirements and plan details and adhere

to them at all times. Most unsatisfactory work can be

traced to lack of enforcement of the specification

requirements.

Engineering supervision should be arranged so

that inspectors check all details of fine grade and

pavement placed during each day. This includes

detailed examination of every joint from placing the

dowel bar assembly to sawing and sealing. A good

practice is to travel up one side of the work and down

the other, repeating the cycle throughout the day.

3.3 Pavement Inspection

Pavement inspection is not merely observation. It is

constant checking to see that all work is being

performed in accordance with good construction

practice and the controlling specifications. At times it

involves stopping operations, reworking or replacing

materials or requiring that work be done over when it

is not correct, and changing methods or materials

when results are unsatisfactory.

When changes in procedure are indicated

because of unsatisfactory pavement results, operations

must be suspended until the changes are made.

Nothing is gained by permitting paving operations to

continue when the resulting pavement is not

satisfactory. It is the responsibility of the Inspector to

bring such matters to the attention of the Engineer at

once for a decision.

The quality of a concrete pavement is a direct

reflection of the quality of workmanship. A pavement

that is durable and that has a good riding surface is

produced only by the constant practice of good

construction methods. Any deviation from good

practice at any time or place will have an adverse

effect on final pavement quality.

Good riding qualities depend on uniformity of

construction. Uniformity begins at the batch plant. If

the batch plant produces nonuniform batches, no

amount of “first-aid” or “emergency” actions at the

paving operation will produce satisfactory, uniform

pavement.

The Concrete Control Inspector’s job is to

check the handling, proportioning and mixing of

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materials according to specifications and to

assure, as nearly as possible, a constant condition of

workability and quality in the resulting concrete. The

two principal sources of difficulty in maintaining

uniform concrete are segregated aggregate and

varying moisture content of the aggregate.

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Manual of Rigid Pavement Practices


4.0 Mechanical Equipment

4.1 General

The riding qualities of a pavement are dependent to a

great extent on the proper operation of mechanical

finishing equipment. The equipment must be in

correct adjustment. It is almost impossible to correct,

by hand finishing a poor surface left by the

equipment. Frequent checking and minor adjustments

as required to compensate for changing conditions

will do much to eliminate surface irregularities.

4.2 Adjustments, Contractor’s Function

Adjustments of equipment are a function of the

Contractor’s forces. Department personnel are not

expected to adjust or advise the Contractor how to

adjust and maintain mechanical equipment, but they

are expected to observe checking of all equipment.

The Inspector should be able to recognize when such

equipment is out of adjustment or not coordinated

with the balance of the paving train. The following

information on spreaders and finishing equipment is

given to provide some knowledge on the operation of

such equipment.

4.3 Spreaders

Concrete spreaders are required when the width of

pavement being placed in one operation is 3.6 meters

(12 feet) or more and the area of any given width

exceeds 8,300 square meters (10,000 square yards).

They must be adjusted to leave the proper amount of

concrete to build the slab. The amount left is

determined by the elevation of a strike off plate which

is located behind the screw, paddle or hopper which

distributes the concrete.

The elevation of the bottom of the strike off in

relation to the top of the forms is shown on an

indicator that is visible to the operator. The

equipment should be checked to make sure that the

indicator shows zero when the bottom of the strike off

is exactly even with the top of the forms.

4.4 Vibrators

When vibrators are used for full width vibration of

concrete paving slabs, they shall be internal type

either with immersed tube or multiple spuds. They

may be attached to the spreader or the finishing

machine, or may be mounted on a separate carriage.

They should not come in contact with the joint, load

transfer devices, subgrade, or side forms. Multiple

spuds should not be spaced further apart than 0.76 m

(2 1/2 feet). Therefore, a minimum of 10 are required

for a full 7.2 meter (24 feet) width paving.

Internal vibrators shall operate at 7,000 to

11,000 impulses per minute. The Contractor is

required to provide the Engineer a method to verify

vibrator frequency. Vibration is required for all

concrete pavement. Small irregular areas require

vibration by hand held or machine mounted

equipment to assure that adequate consolidation

for the full depth and width is achieved without

segregation.

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4.6 Mesh Installer

4.6.1 GeneralPavement mesh may be installed by placing it on

top of the full depth of concrete, then vibrating it into

position using an approved mesh installer. This

method eliminates the need for placing two courses of

concrete and thereby eliminates the possibility of a

plane of weakness between two separately placed

courses. Control of the placement of the mesh within

the slab has been found to be more accurate than

when placed between courses, based on

measurements of cores removed for checking

thickness requirements. Another advantage of this

method is that a bulkhead can be placed readily and

quickly in the event of breakdown since the concrete

is placed full depth, and not in two separate courses.

4.6.2 TypesTwo types of machines have been approved for

use in vibrating the mesh into position. One type

consists of a grid of steel plates approximately 4.6 m

(15 feet) in length and extending the full width of

pavement being placed. The machine which is self-

propelled is positioned over the mesh, stopped, the

mesh depressed into the freshly placed concrete and

moved ahead to repeat the operation.

The other type also is self-propelled and consists

of long tapered longitudinal runners across the width

being placed. This machine gradually depresses the

mesh into position within the fresh concrete using an

oscillating tamping motion while continuously

moving forward.

4.6.3 TolerancesSince there is a forward movement during

placing, the latter type of machine may cause

movement of the mesh across transverse contraction

joints when not properly adjusted. When using a

machine of this type, periodic checks shall be made

by uncovering the mesh

Vibrators shall be turned off when the machine

on which they are mounted is stopped.

4.5 Transverse Finishing Machines

4.5.1 Operating ConditionThe transverse finishing machine first should be

checked for its operating condition. The bearings,

especially those of the cranks actuating the oscillatingscreeds, should fit snugly so that the screed will

reverse direction without slap which would rack theforms.

4.5.2 End Plates and ScreedsThe end plates which slide on the forms should

be inspected for wear and reversed or replaced if

necessary. The screed should be checked forstraightness or crown if one is required. This is done

by placing a block on the forms under each end of thescreeds and stretching wires at both front and back

across from form to form. The crown then is checkedby measuring the offsets from the wire to the screedas outlined in 17.3. Adjusting bolts can be loosened

or tightened to secure proper adjustment.The exact tilt required in each screed cannot be

determined until construction begins. However, at thestart of paving operations the front edge of the

forward screed should be titled about 5mm (3/16inch) and the rear screed set level. Adjustments can

be made readily by end bolts provided for thispurpose.

4.5.3 StrokeSprings are used as shock absorbers to prevent

slap at the end of the stroke. These should be

checked to insure that they are in compression at alltimes. The screed lift chains must be long enough

that they are not tight at the end of the stroke or thescreed will be lifted off of the forms at every

oscillation.

Finally, the wheel scrapers should be tightened

so that they will be sure to keep the wheels clean.

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at joint assemblies to assure that the specified

clearance of 305 ± 51 mm (12 ± 2 inches) is being

maintained on each side of the center of the joint. If

the position of the mesh is found to be outside of

tolerance, it should be corrected and the machine

adjusted at once, or its use immediately discontinued.

Production may be continued without the mesh

installer by changing to the two-course method.

Both types of machines can be adjusted to control

the depth of the mesh. Therefore, depth checks shall

be made daily to assure control of the depth of mesh.

Specifications require the mesh to be placed between

64 mm (2 1/2 inches) and T/3 plus 25 mm (1 inch), T

being the thickness of the slab, below the surface of

the pavement. When mesh is found to be outside of

tolerance, immediate adjustment shall be made.

It may be necessary to use the two-course method

at expansion joints and at abutting pavements, if the

machine with the long tapered runners cannot position

the mesh properly. The two-course method should be

employed any time satisfactory performance of the

machine is not being obtained.

4.7 Combination Float Finisher

4.7.1 TypesThe combination float finisher commonly is used

to provide the final mechanical finish on a pavement.

The machine which consists of two screeds and a

float is designed for use on a 7.2m (24 foot)

pavement.

4.7.2 AdjustmentThe front screed of the machine is a conventional

reciprocating screed which rides the forms. The rear

screed and float, however, are suspended from an

approximately 4.9m (16 foot) beam platform and do

not receive any support from the forms. The

elevation of both the rear screed and the float is

determined by adjustment of the hangers which

connect them to the platform. As a result, variations

in forms do not significantly affect the plane of

operation of either the rear screed or float. The key to

smooth finishing with this machine is the rear screed

since it is the final screeding tool and operates from a

4.9m (16 foot) straightedge essentially free from

influence of deviations in the forms.

Spring loaded shoes are fastened to both ends of

the rear screed to keep the screed in contact with the

forms. The springs are sufficiently strong so that the

rails will be kept clean, but not so strong that they

will cause the screed to raise when an undetected

highpoint in the forms is being traversed.

The float does not oscillate but moves forward

with the machine providing a smooth trowelled

surface. It is approximately 0.7m (30 inches) in

length and rides on the slab between the forms. Both

of the screeds and the float are provided with devices

which permit rapid changes in crown. These devices

make it possible to change crown at super-elevated

sections without delay. Crown is checked as

described in 4.5.2 and 17.3.

4.8 Transit Mix andCentral Mix Equipment

Before beginning paving operations and at regular

intervals during paving, concrete plants and hauling

units shall be checked for proper condition. Water

metering devices and admixture metering devices

should be checked to assure proper calibration within

specified tolerances.

4.8.1 Transit MixersTransit mixers should be checked to determine if

the counters are functioning properly. After having

been mixed for not less than 70 revolutions at mixing

speed, the mixer should contain concrete of uniform

consistency and be able to discharge the batch without

7

Chapter 4.0: Mechanical Equipment


segregation. Since this determines

acceptablility, mixers that do not perform in this

manner should not be approved, and, if encountered,

their use should be discontinued. Sources of trouble

are badly worn blades and leaky valves which prevent

mixers from producing uniform concrete. They

should not be used until corrected.

4.8.2 Central MixersCentral mixers should be checked to see that the

mixer is capable of mixing and discharging the large

volume of conrete with uniformity. During paving,

the Contractor or ready mix supplier must keep mixer

blades free from concrete build up and excessive

wear.

4.8.3 Hauling UnitsWhen the concrete is to be transported to the

paving site in dumptrucks or other non-agitating units,

these bodies should be checked to see that they are

water tight and free of objectionable corners or

internal ribs where concrete may accumulate.

Canvass covers to shield concrete from sun and wind

shall be provided when required by the Engineer.

4.9 Slip Form Pavers

Slip form pavers are generally of two basic types.

One has an extrusion meter which shapes and

extrudes the concrete pavement, while the other type

has the same features as the combination float finisher

which shapes, consolidates and then finishes the

pavement in a manner similar to conventional

methods.

4.9.1 AdjustmentThe extrusion meters or screeds and the float

should be checked for proper crown setting before

using. They should be adjusted if necessary to

conform to the typical section.

4.9.2 Tampers and VibratorsSlip form machines usually are equipped with

both tampers and vibrators. Both should be checked

to assure they are in working order before paving

starts. Vibrator frequency shall be monitored

periodically to assure the specified impulses per

minute are being obtained.


8


5.0 Batch Plants

5.1 Storing Aggregate

5.1.1 Preparing SiteStockpiles should be placed on areas which are

paved, prepared by using sheet metal, wood plank,

etc., or they may be placed directly on the ground.

When building stockpiles on existing ground, the area

should be firm, cleaned of foreign material and

shaped to provide drainage. No aggregate is to be

removed from the stockpile within one foot of the

ground until the final clean up. Aggregate within this

area should be processed to meet specifications before

permitting its use.

Stockpiles should be built in such a manner that

different aggregate does not become mixed and that

the aggregate does not segregate.

5.1.2 StockpilingIn building the stockpiles of coarse aggregate,

continual care must be exercised to prevent segrega-

tion through improper handling. A clam bucket

operated by a crane of sufficient size that the center of

the pile can be reached from the edge is best for this

work. In depositing the aggregate, the bucket should

be lowered close to the level where the aggregate is to

be deposited before releasing the aggregate. This pre-

vents rolling of the larger aggregate to the bottom of

the pile to cause segregation. As the pile increases in

height, each layer of aggregate should be benched

back to form tiers that will help limit rolling and

segregation.

Other equipment may be used in conjunction with

a clam bucket.

If the Contractor uses front end loaders to build the

pile, they must have clean rubber tires if they are to

operate on the pile. As with the clam bucket, the drop

should be as little as possible when depositing the

aggregate. Once on the pile, the front end loader

should not be permitted to move on and off of the pile

as this may cause contamination.

Pushing of large aggregate as with a bulldozer is not

permitted, as this causes segregation. Use of steel treads

on the pile is not permitted as they tend to crush the

aggregate.

Small aggregate does not segregate as easily as

large aggregate because the smaller pieces are less

likely to roll down the side of the pile.

Any operation which might result in segregation,

degradation or contamination shall not be permitted.

When these conditions appear evident, a test for

gradation shall be run, and, if substantiated, the

operation shall be adjusted.

5.1.3 Scales

The specifications require that concrete materials

be measured by weight. The scales shall be checked

for accuracy with standard test weights as outlined in

the Manual of Procedures for Concrete.

5.1.4 HandlingMaterials should be placed in the batch bins by

dumping into the middle of the bin with as short of a

drop as possible. Keeping the drop to a minimum

reduces the chance for segregation in handling

aggregate, as well as in handling concrete.

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6.0 Subgrade

6.1 Preparation

After embankment has been placed and compacted

and excavation has been completed, the subgrade is

brought to the required grade, cross section and

density. The subgrade shall be checked after it has

been prepared to assure compliance with surface and

density requirements.

6.2 Requirements

The surface of the subgrade is shaped to bring it

within the allowable tolerance of the typical cross

section. The surface shall not vary more than:

1. 13 mm (1/2 inch) from a 3 m (10-foot)

straightedge applied parallel to the centerline of

the pavement.

2. 13 mm (1/2 inch) from the plan grade.

The subgrade shall be compacted to a depth of

305 mm (12 inches). Soil subgrade with maximum

dry density of 1600 - 1680 kilograms per cubic meter

(100-105 pounds per cubic foot) shall be compacted

to not less than 102 percent of maximum dry density.

All other soils for subgrade shall be compacted to not

less than 100 percent of maximum dry density.

Soils having maximum dry weights of less than

1600 kilograms per cubic meter (100 pounds per

cubic foot) are considered unsuitable for use in

subgrade and when found in the upper 300 mm (12

inches) shall be removed and replaced with suitable

soil or granular material. When these lightweight soils

are encountered and when satisfactory stability cannot

be obtained, the subgrade shall be corrected in

accordance with 203.13 of the specifications.

Detailed instructions are contained in the Manual of

Procedures for Earthwork. The surface is to be

maintained in a smooth condition to provide quick

drainage and to prevent ponding of water.

6.3 Proof Rolling

Where proof rolling is specified the compacted

subgrade shall be checked in accordance with 203.14

of the specifications. Instructions for performing this

work are detailed in the Manual of Procedures for

Earthwork.

6.4 Tolerance Check

The completed subgrade shall be checked for

compliance with the requirements of 6.2. When

checking is done the limits of the area checked should

be recorded along with a statement that the subgrade

conforms to requirements. This data should be

recorded on Form C-119 Inspector’s Daily Report,

Documentation Procedures, D-1.

Any area found outside of the allowable

tolerances must be corrected and rechecked before the

area is approved for subbase and/or pavement.

10


7.0 Subbase

7.1 General

Subbase is provided by plan for all concrete

pavements with only a few exceptions. It is possible

that there may be pavements without subbase but they

will be the exception rather than the rule. The typical

section of the plans indicates the depth and width of

compacted subbase materials. Therefore, the

Inspector should check the typical section prior to

inspecting this operation.

Stabilized subbases may be specified on selected

projects. Bituminous, cement and aggregate lime-fly

ash bases have been a design feature on several

projects. If encountered, these bases should be

constructed in accordance with contract requirements.

Cement stabilized base should meet requirements of

Supplemental Specification 804. Bituminous bases

usually are specified in accordance with 301. Plan

and Proposal Notes should be reviewed for special

requirements when stabilized subbases are required.

7.2 Placing Subbase

Subbase material conforming to the grading specified

in the plan or proposal shall be placed with an

approved spreader. The subbase may be placed in a

single lift or layer provided the compacted depth does

not exceed 200 mm (8 inches). The moisture content

will be determined from the test section. If the

material does not contain sufficient moisture when it

is spread, it shall be sprinkled with water. Care should

be exer-cised to avoid softening the subgrade when

watering.

Immediately after the subbase material has been

spread it shall be compacted until the density is at

least 98 percent of the weight obtained in the test

section. This is the minimum required for all the

subbase. Detailed instructions for the test section are

outlined in the Manual of Procedures for Earthwork.

7.3 Fine Grading

The surface of the subbase is left approximately 25

mm (1 inch) above grade after compaction has been

completed. Then, after forms have been set to grade

for form paving or the stringline is set for slipform

construction, the slight excess is removed during the

operation of the subgrader. The subgrading or fine

grading operation should result in a slight removal so

that the trimmed surface is compacted thoroughly

without low areas. Low areas require the addition of

material, compacting and regrading resulting in a

delay in progress of fine grading.

When automated subgraders are used they will

precede the setting of forms. Grade will be

maintained from a preset stringline that will be

parallel to the grade line. After final trimming the

surface will be treated the same as for conventionally

graded base.

Loose subbase material windrowed along the

inside of the forms cannot be removed by machine so

removal of this material by use of a shovel is

necessary. This shall be done before recompacting.

The trimmed surface left by the subgrader

should be compacted using a light or medium roller to

restore density to the surface. This rolling operation

also smooths the surface and reduces the friction

between the subbase and the pavement.

11


7.4 Pin Template

The surface of the subbase shall be checked using a

multiple pin template operated on the forms. The

template is to be operated behind the subgrader and

roller. Any high or low spots encountered shall be

corrected immediately, then rerolled and rechecked

before continuing.

7.5 Moisture Control

Moisture is controlled by spraying the subbase prior

to fine grading, preferably in the late afternoon of the

day before fine grading. This provides the moisture

necessary for density and provides time during the

night for uniform moisture distribution. After

removal of excess material during fine grading,

moisture is present for the final surface compaction.

Just prior to placing concrete, the subbase should be

sprinkled again to replace moisture lost by surface

evaporation so that the subbase will not absorb water

from the concrete. Loss of concrete water can result

in a rapid slump loss and early setting of the concrete

before it can be finished properly.

7.6 Rechecking Forms

The subgrader is usually one of the heaviest pieces of

equipment operating on the forms. Therefore, this is

an opportune time for the Inspector to observe the

forms for excess movement or displacement. Areas

where movement or displacement is noticed should be

rechecked for compliance with requirements before

placing concrete.

It is good practice to recheck the alignment and

grade of forms, the form locks and the pin keys after

fine grading. Some contractors assign employees to

this job. The Inspector should check these items

regardless of the Contractor’s operation to assure that

any irregularities have been corrected. Since the

paving equipment relies on the forms for support, it

cannot be expected to produce a quality riding surface

when yielding or improperly set forms are

encountered.

7.7 Recording Checks

The Inspector shall note on the Inspector’s Daily

Report, Form C-119 the limiting stations of the area

checked that conformed to the requirements.

For slipform paving, spot checks of completed

subbase should be recorded in the project records.

12



8.0 Forms

8.1 General

Forms are a potential source of trouble because they

serve as tracks for all paving equipment, except

mixers, in addition to serving as forms for the

concrete. Since developments in paving equipment

have provided heavier equipment, the forms play an

increasingly important role in the construction of

smooth pavements.

8.2 Checking

Before any forms are set on a project they are to be

inspected to see that they comply with specification

requirements. Forms shall be not less than 3 m (10

feet) in length and have adequate joint locks for

joining ends of abutting form sections tightly. Also,

they shall have sufficient pin pockets for setting

securely so that they will withstand the operation of

the paving equipment. Forms that are found to be

distorted more than 3 mm (1/8 inch) on the top or

more that 6 mm (1/4 inch) in alignment shall be

rejected. Forms that are rejected are to be marked

conspicuously. They are not to be used unless they are

repaired so that they will comply with requirements.

Forms are reused continuously. Therefore,

inspection of forms must be continuous. Anytime

forms are found out of tolerance they shall be

rejected.

8.3 Setting

Forms are to be set true to line and grade on a

thoroughly compacted subbase with uniform bearing

throughout their entire length and width. The

building of pedestals of earth or other shimming to

bring forms to the required grade shall not be

permitted. Whenever adequate and uniform form

support is not obtained, the forms shall be removed,

the base corrected and compacted, and the forms

reset. At least three form pins are to be used in each

ten foot length. These pins shall be long enough to

hold the form in position during the placing and

finishing operations.

Grade for forms is prepared using a form grader.

A stringline is set to serve as a guide for controlling

the grade during the operation of the form grader. An

automatic subgrader operating from a preset grade

line may be used to prepare the entire width of

subbase before forms are set. If such a machine is

used, the forms may be set to correct line and grade, a

planer usually is operated on the forms to assure the

subbase is to the proper grade. Whether or not a

planer is used, a pin template shall be used to check

the surface of the subbase.

8.4 Keys and Locks

Pin keys are to be straight and free moving in the

pockets and capable of holding the forms tight against

13


the pins. The joint locks are not to be bent or wornand must be capable of holding the ends of the formsin true alignment. The pins and locks are checkedwhen the forms are set but should be rechecked justprior to placing of concrete and tightened ifnecessary. At the same time a final visual check is tobe made to insure forms are at proper line and grade.Smooth riding pavement with good surface finish isextremely difficult to obtain with poorly aligned and

set forms.

8.5 Oiling

The forms are to be oiled prior to placing of the

concrete. When tie bars or hook bolts are fastened to

the forms, oiling should be done prior to placing of

these units.

14



9.0 Joints

9.1 General

Joints may be classified as transverse and

longitudinal. Transverse joints are further classified

as contraction, expansion and construction joints.

Detailed instructions for joints are found in the

specifications and in Standard Construction Drawing

BP-2.1M and BP-2.2M (BP-2.1 and BP-2.2). The

Inspector should know the requirements of the

specifications and the drawings before inspecting

joint construction.

9.2 Longitudinal Joint

Joints between adjoining lanes of pavement are

longitudinal joints. They are necessary to control

cracking in the longitudinal direction due to the

warping stresses in wide concrete slabs. Joints

between separately placed adjoining lanes are

longitudinal joints as well as construction joints. In

general the maximum pavement width without a

longitudinal joint is 4.9m (16 ft) for ramp pavements.

9.2.1 TiesTie bars or hook bolts are required to tie the

lanes to prevent them from moving apart or from

settling unevenly. Since they tie the lanes together by

bond, tie bars or hook bolts are not to be oiled.

9.2.2 PlacingBoth tie bars and hook bolts should be placed

in accordance with requirements of Standard

Construction Drawing BP-2.1M (BP-2.1). Tie bars

are 16mm (5/8 inch) in diameter, 760mm (30 inches)

in length and spaced at 760mm (30 inches). They

should be approximately at right angles and centered

at the longitudinal joint.

Tie bars may be set on chairs prior to concrete

placement or installed in the concrete after it is placed

and spread. When placed in the plastic concrete an

approved mechanical device shall be used to install

the tie bars at the proper depth and location. The

mechanical installing device shall install tie bars after

the concrete is placed to its full depth and after mesh

is in position. The device shall be located in the

paving train so as to assure consolidation of the

concrete around the tie bars.

Bent tie bars are not permitted in longitudinal

construction joints.

Hook bolts generally are used in longitudinal

construction joints. One half of the device is attached

to the form for the first lane placed. Before placing

concrete in the adjoining lane, the other half is

coupled to the embedded part. The hook bolts are to

be securely fastened to the forms so they are

positioned properly in the slab. The right angled

hooks on each side of the coupling anchor into the

slabs to provide the tie. The position of the hooks is

not important, that is, they do not have to be turned

down, up or sideways.

9.3 Contraction Joint

Contraction joints are required to be spaced in the

pavement at intervals not to exceed the maximum

spacing indicated in the Contraction Joint Spacing

15


Table of Standard Construction Drawing BP-2.2M

(BP-2.2). This type of joint is necessary to control

transverse cracking that occurs due to shrinkage and

contraction as the concrete cures and hardens.

9.3.1 DowelsLoad transfer dowels are used to transfer loads

across the transverse joints. Dowels are smooth,

round steel bars, 457 mm (18 inches) in length,

spaced at 305 mm (12-inches) intervals at mid-depth

of the pavement slab in accordance with Standard

Construction Drawing BP-2.2M (BP-2.2). All dowels

used in concrete pavement are to be epoxy coated as

per 709.13. The entire dowel including the ends is to

be epoxy coated.

To function properly dowels should be parallel

to the surface and parallel to the centerline of the

pavement since expansion and contraction movements

occur in this direction. To assure proper alignment of

dowels, a cage or basket is used. This, together with

the dowels, is called a dowel assembly. Dowel

assembly wires as well as the dowel are required to be

epoxy coated according to 709.13 of the CMS.

The diameter of the dowel required in the

pavement depends on the pavement thickness. Unless

otherwise specified in the plan the dowel diameter

required is to be as shown in the Dowel Size Table

of Standard Construction Drawing BP-2.2M

(BP 2.2).

9.3.2 Placing AssembliesAssemblies are to be positioned not to exceed

the maximum spacing and must be perpendicular to

the centerline and forms. Spacing may be controlled

by measurement along the forms. Locating the

transverse alignment may be by any method that

assures a right angle to the centerline. On curves the

joints should be approximately on radial lines.

After the alignment is established, a string line

stretched between forms will assist in placing the

dowel assemblies properly. Transverse contraction

and expansion joints must be continuous across the

full width of pavement placed. Therefore the line of a

joint in a lane already placed must be continued in all

other adjoining lanes.

When properly located and placed, joint

assemblies are anchored in place. At least eight 13

mm (1/2-inch) steel pins 460 mm (18 inches) in

length are required to hold each 3.6 m (12 foot) unit.

The pins are driven at an angle to brace the assembly

from lateral movement and to prevent vertical

displacement when concrete is placed. Two of the

pins are driven opposite each other at each end of the

assembly, and the remaining four are driven in a

staggered pattern on each side. Care must be taken to

avoid hitting the assembly when driving the anchor

pins. If wires of the basket are bent, the dowels may

be thrown out of line and require the entire assembly

to be rejected unless it can be removed, straightened

and reset properly. Any assembly badly distorted

should be rejected. The epoxy coating must not be

damaged during the above operation.

If concrete pavement is placed on an existing

pavement or stabilized base, the bowel baskets shall

be held firmly in position by use of a power driven

fastener and an appropriate clip at 6 locations along

the assembly (3 on each side of the assembly). The

clips shall secure the basket from lateral and vertical

displacement during concrete placement.

If the assembly is placed on a subbase consisting

of sand, a minimum of six steel bearing plates

approximately 127 mm (5 inches) square shall be

placed under each 3.6 m (12-foot) assembly unit.

Bearing plates also are required when any subbase

material is used which permits distortion or settlement

of the assembly due to poor stability. One bearing

plate is to be used with each of the four end anchor

pins with the others spaced uniformly along the

assembly. Shimming with pebbles, stones, etc. shall

not be permitted. If shimming is necessary, it is

16



obvious either that the subbase is not prepared

properly or the dowel assembly is bent or misaligned.

In either instance, the subbase or assembly shall be

rejected until corrective action has been completed.

Specifications provide that dowels may be placed

in the full thickness of pavement concrete by a

mechanical device approved by the Engineer. If the

Contractor contemplates this method of installation

special instruction should be requested from the

Construction Section of the Office of Highway

Management through the District Construction

Administrator. This method of dowel placement has

been used successfully for many years in construction

of plain concrete pavements. It is intended to permit

this method provided the Contractor is able

continuously to install dowels properly.

Loose dowels are placed on an installing rack of a

self-propelled machine and installed by vibrating

them into the plastic concrete. After the dowels are

placed at mid-depth, the rack is withdrawn leaving the

dowels in position supported by the concrete. The

dowels are to be installed after the concrete is placed

to its full depth and after the mesh is positioned

properly. The only operations permitted after

positioning the dowels are machine and hand

finishing of the surface of the concrete.

9.3.3 Preventing BondFor dowels to function properly in the concrete slab,

they must be oiled with a thin coating of oil for at least

one half their length to prevent the concrete from

bonding to them. Most of the dowel assemblies have

one end of the dowel welded to the basket wire. It is the

free end opposite the welded end that must be oiled.

Dowels shall be oiled the same day that they are to be

covered with concrete. Care should be exercised to see

that at least half the dowel is covered completely. It is

always better to oil more than half the length of each

dowel to be certain that bond is prevented so that the

joint will function properly.

Epoxy coated dowels should be inspected to

assure the coating is continuous on the ends and

lateral surface of the dowel and that the coating is not

perforated, cracked, or otherwise damaged, in which

case it shall be rejected. In addition, the coating shall

be free from holes, voids, contamination, cracks, and

there shall not be more than two holidays (pinholes

not visually discernable) in any 305 mm (12 inch)

length of the coated dowel. The free ends of the

dowels shall be free of burrs or projections.

9.3.4 TiesAfter assemblies have been set and anchored

properly, the shipping ties or clips used to hold both

halves together during shipping and handling must be

cut. The shipping wire is normally cut at two

locations and removed immediately prior to placing

the concrete. The ties are usually a small diameter

wire hooked or tack welded to the basket assembly wire.

9.3.5 Checking AssembliesAfter being set, anchored and oiled the dowels are

to be checked to assure that they are parallel to the

subbase surface and the centerline of the pavement.

Spot measurement checks of the distance between the

dowel and the forms, made at each end of the dowel,

provides a check for being parallel to centerline. The

distance to each end of the dowel must be equal for

the dowel to be parallel to the forms and the

centerline. After some experience, this check can be

a visual check since dowels out of alignment stand

out when observing them in relation to the forms.

An adjustable A-frame level is used to spot check

several dowels in every assembly unit to assure that

all dowels are parallel with the surface of the

pavement. The level first is placed on the forms or

subbase adjacent to a basket assembly. Then the level is

placed on the dowels. The bubble will indicate level if the

17

Chapter 9.0: Joints


dowel assembly is set properly and is parallel to the

surface of the pavement. At least three dowels are to

be checked in each 3.6 m (12-foot) section, one at

each end and at the middle. If the dowels are not

parallel with the surface when checked, the assembly

must be adjusted and rechecked. If proper alignment

cannot be obtained, the assembly must be removed

and replaced.

Immediately prior to paving, shipping wires are

to be removed. Shipping wires run the same direction

that the dowels do through the joint.

9.4 Expansion Joint

Relief for compression stresses in hot weather is

provided at bridges and at intersections. This relief is

in the form of expansion joints. Nonextruding

compressible material is placed in the transverse joint

so that expansive forces can be relieved by the

compressible material. Standard 460 mm (18 inch)

long epoxy coated dowels are required for load

transfer, in all expansion joints. Damage to bridges

and abutting concrete is averted by the use of

expansion joints. The expansion joint also permits

contraction movement in addition to absorbing

excessive expansion. Proper size dowel holes shall be

punched or drilled into the preformed expansion joint

filler in order to insure a tight fit when the dowel is

pushed through it.

9.4.1 Expansion MaterialPreformed compressible material 25 mm (1 inch)

thick is installed in a dowel assembly at the location of

the expansion joint. It must be set perpendicular to the

top of the expansion forms as well as perpendicular to

the line of forms and the pavement centerline. The

material must extend down to the top of the subbase

and to the side forms so that free movement is allowed

throughout the entire joint. The top of the expansion

material is held 25 mm (1 inch)below the surface. It

will be permissible to place the expansion material

closer to the surface to facilitate sawing of this joint,

provided all material is removed to a depth of 25 mm

(1 inch). This area shall be sealed using a hot applied

joint sealer meeting the requirements of 705.04

(ASTM D-3405).

9.4.2 CapsA cap is placed on the free end of each dowel to

create a void in the concrete to permit expansion

movement. This cap must be placed on the free end

after the dowel has been oiled. The cap contains a

crimp to position it to provide for the 25 mm (1-inch)

void. These caps must not be forced beyond the

crimp or there will not be space for expansion and the

joint will not function correctly.

9.5 Construction Joint

Construction joints are transverse bulkheads placed at

the conclusion of each day’s paving or when

production is interrupted for more than 30 minutes.

These joints are formed by using an adequate

bulkhead that will provide a straight joint. The

bulkhead shall have openings provided for individual

dowels or an assembly of dowels. The bulkhead must

be shaped to conform to the typical section of the

pavement.

Construction joints may be located at contraction or

expansion joints in concrete pavement but shall not be

located closer than 3.0 meter (10 feet) to any other

parallel joint. In plain concrete pavement or base, they

shall not be closer than 1.8 m (6 feet) to another

transverse joint.

9.5.1 DowelsSmooth epoxy coated dowels shall be used in

construction joints and care should be exercised in

placing them parallel to the surface. The dowel size

shall be as required for the contraction joints in the

adjoining pavement. For pavement lanes of even 0.3

m (foot) width increments, dowels will be spaced at

300 mm (12-inch) centers beginning 150 mm (6

18



inches) from the longitudinal joint. Where other

widths are specified, the spacing between the end

dowel and the outside edge of the lane may be

increased up to 300 mm (12 inches). A dowel shall

be placed 150 mm (6 inches) from the outer edge of

the pavement when the spacing between the end

dowel of the basket and the outside edge exceeds 300

mm (12 inches).

At skewed joints between approach slabs and

approach pavement, care should be exercised to

position the dowels parallel to the centerline. Recent

experience indicates movement occurs at such joints.

Provision should be made for this movement by

placing dowels the same as for contraction joint.

The joint may be hand formed or sawed to the

same dimensions required for transverse joints in

adjoining pavement.

19

Chapter 9.0: Joints


10.0 Sawing and Forming Joints

10.1 General

Sawing of joints has resulted in improvement in the

riding quality of concrete pavements and higher

quality concrete in the joint area. With sawing, the

concrete is placed and finished in a continuous

operation without disturbing the surface at every joint

for hand forming a groove. In lieu of this laborious

hand operation, the groove is sawed in the hardened

concrete after the surface has been machine finished

and has hardened sufficiently to saw. The uniform

groove thus created, controls transverse cracking and

provides a reservoir for the joint sealer.

Sawing is required for all contraction joints.

Expansion joints may be sawed or hand formed. See

451.08(c). Longitudinal construction joints either

may be hand formed or sawed. When properly done,

sawing produces uniform joint openings and,

therefore, is preferable.

10.2 Requirements

Joint openings are to be constructed in accordance

with the requirements of Standard Construction

Drawings BP-2.1M and BP-2.2M (BP-2.1 and BP-

2.2). Contraction joints are sawed in a progressive

manner as soon as possible without causing excessive

raveling of the concrete. Slight raveling is not

objectionable but rather is an indication that sawing is

being done at the proper time.

The timing of the sawing operation is critical for

contraction joints. Sawing must be done after the

concrete hardens sufficiently to support the sawing

equipment and to avoid spalling and raveling. This

operation cannot be tied to normal working shifts but

must be accomplished when the concrete is ready. A

standby saw is required at the paving site in the event

of breakdown or inability of one machine to maintain

necessary progress.

Inspection should include random checking of

each day’s sawing to assure the width and depth

specified is attained. Saw blades will wear with use

so continued checks must be made.

Since the timing of sawing is of utmost

importance for contraction joints, it should be

emphasized, and inspectors assigned to this operation

must be aware of this importance. However, the

control of sawing is the Contractor’s responsibility

and the Inspector should avoid making decisions as to

when to saw.

Timing of the sawing of longitudinal joints is

not as critical. However, specifications require the

sawing to be done within three days after concrete is

placed.

Sawing may be done wet or dry, and the cut

must be cleaned by a jet of water, if sawed wet, or air

under pressure, if sawed dry.

10.3 Contraction Joint

Contraction joints in pavements 255 mm (10 inches)

thick or less shall be sawed to a minimum of 1/4 of the

pavement thickness and to a width shown in the

standard, measured at the time of sawing. For

pavement that is greater than 255 mm (10 inches) thick

20


the sawing depth shall be 1/3 the slab thickness. A

tolerance of ±1.6 mm (1/16 inch) is allowed in the

width of the saw cut.

The depth of 1/4 or 1/3 the pavement thickness

is the minimum necessary to control transverse

cracking. Following this initial sawing the Contractor

must saw to the width and depth detailed in Standard

Construction Drawing BP 2.2M (BP-2.2). This

additional sawing is necessary to install the preformed

elastomeric compression joint seal.

The width of the saw cut must be controlled to

within the tolerance to create a uniform width opening

necessary for the installation of the joint filler. The

filler is designed to function within the width

specified, and any variation may affect its

performance and create installation problems.

If the Contractor desires, sawing may be

accomplished in two operations provided:

1. The first operation consists of sawing to the

minimum depth specified using a 6 mm ± 1.6

mm (1/4 inch ± 1/16 inch) blade.

2. The second operation consists of sawing to the

specified depth using a blade of a width within

the specified tolerance. The second sawing is to

be performed when the temperature is 21° C

(70F) or above.

This method provides relief when critical sawing

conditions exist and provides a uniform width opening of

desired width for installation of joint seal. Use of a

narrow blade permits sawing earlier to avoid random

cracking. Any raveled edges are dressed during the

second sawing.

10.3.1 Random CracksIf a crack appears ahead of the machine during

sawing, it is an indication that sawing is late. When

such cracking is noted, sawing of that joint is to be

stopped immediately and the saw moved ahead several

joints. Saw a joint, move ahead several more joints,

and saw another joint. Continue skipping three or four

joints and sawing every fourth or fifth joint until

sawing is back on schedule. The presence of slight

raveling indicates proper timing of sawing. When

back on schedule every joint should be sawed in

order. After sawing has been completed for the day’s

production the saw can be returned to saw the joints

skipped. The standby saw may be pressed into

service to saw the joints skipped if an experienced

operator is available.

This procedure of skipping ahead and sawing

every fourth or fifth joint relieves the stresses that

occur when the concrete hardens and shrinks during

curing. Once these stresses are relieved the sawing of

the in-between joints is not as critical but should be

done as soon as possible.

The pavement normally is subjected to

expansive forces the following day when the

temperature rises. When temperatures drop the

evening of the following day, the pavement again

experiences shrinkage stresses and all joints originally

bypassed must be sawed before these stresses result in

random cracking.

Pavement placed should be sawed the same day,

possibly six to eight hours after placing. Concrete

placed late in the day may not harden to permit

sawing until the next day, but sawing must be

completed before the following late afternoon

temperature change as shrinkage will again occur as

temperatures drop.

Joints in lanes placed adjacent to a previously

placed lane that are tied together must be sawed as

soon as possible to prevent uncontrolled cracking. If

a new lane is tied to existing concrete that is

expanding and contracting with changes in

temperature, stresses will be transmitted to the new

slab unless joints are sawed as quickly as possible.

The following provisions are important to obtain

quality sawed joints in these areas:

1. All transverse joints, except construction joints

in the second lane of pavement shall be opposite

and in line with those in the first lane.

2. The sawing of the joints shall be done as soon as

the saw can be operated on the pavement without

21

Chapter 10.0: Sawing and Forming Joints


damaging the surface or without raveling of the

newly cut joint.

3. Joints opposite those in the first lane placed

where movement is indicated by cracking, shall

be sawed first.

4. The cut is to be made from the old slab to the

outside or open edge of the new slab being

sawed.

A sudden drop in temperature, a wide range

between day and night temperatures or a cold rain

creates additional problems when sawing contraction

joints. These conditions add stresses due to thermal

changes to the shrinkage stresses and make the timing

of sawing doubly critical. When these conditions

occur or are anticipated increased attention must be

given to the sawing operation to assure control of

cracking.

10.4 Longitudinal Joint

Longitudinal joints shall be used when called for in

the plans on the typical sections and shall be

constructed in accordance with Standard Drawing BP

2.1M (BP 2.1). Tie bars shall be 16 mm (5/8 inch)

diameter, round, deformed steel, 760 mm (30 inches)

long and spaced at 760 mm (30 inches) center. Tie

bars can be supported on chairs, or they may be

installed by a mechanical installing device. Bent tie

bars are not permitted. The longitudinal joint

between adjoining slabs poured in separate operations

shall be a butt joint with hook bolts or tie bars unless

otherwise shown on the plan as untied. Expansion

anchors, if used, shall be installed per manufacturer’s

recommendations and the hook bolt screwed into the

anchor.

In pavements 255 mm (10 inches) or less sawed

longitudinal joints between adjoining lanes placed at

the same time shall have a minimum depth of 1/4 of

the pavement thickness. In pavements greater than

255 mm (10 inches) the depth of sawing shall be 1/3

of the pavement thickness. The width shall be

approximately 3 mm (1/8 inch). The minimum depth

is necessary to control cracking due to warping

stresses. The width of this joint is not critical except

that it should be uniform for ease in sealing.

The longitudinal joint between separately

poured lanes may be sawed or formed. If formed, an

insert 25 mm (1 inch) minimum in depth and tapered

9.5 mm (3/8 inch) at the top to 6.5 mm (1/4 inch) at

the bottom must be inserted into the plastic concrete

to form a void for the joint filler. The insert must be

placed carefully against the existing concrete at the

proper depth. When the concrete has set, the edge of

the plastic concrete is rounded using an edger of the

specified radius. The insert must be removed

carefully at the proper time, and the groove should be

tooled with an edger if necessary.

In lieu of hand forming, the concrete may be

placed without an insert and then carefully edged

using an edger having a 3 mm (1/8 inch) radius. This

edging creates a line for sawing the groove at a later

time. This joint is formed for its full depth.

Therefore, the time of sawing and depth of saw cut is

not critical.

In lieu of using a form or hand tooling the

longitudinal joint in separately placed lanes, the joint

can be sawed. The saw cut, however, should have a

minimum depth of 13 mm (1/2 inch) and a minimum

width of approximately 6 mm (1/4 inch).

When edging the longitudinal joint, an edger

having a 3 mm (1/8 inch) radius shall be used as

compared to a 13 mm (1/2 inch) radius edger required

for the outside edge of pavements.

10.5 Expansion Joint

Expansion joints are required adjacent to bridge

approach slabs at distances of approximately 6 m (20

feet) and 18 m (60 feet). Expansion joints may also be

detailed in the plan at other locations. All expansion

joints are dowelled and allow for the pavement to

22



expand or grow due to temperature variations. A

standard expansion joint allows for 25 mm (1 inch) of

expansion.

If the pavement consists of two or more

separately placed lanes, the expansion joints shall be

a continuous straight line for the full width of the

concrete pavement, including concrete shoulders. All

expansion joints are perpendicular to the centerline

unless adjacent to skewed approach slab.

Inspectors shall assure that the 25 mm (1 inch)

thick expansion joint filler is held rigidly in position

and extends full width of all lanes. The expansion

joint filler shall be the required height and shall

extend to the top of the subbase (or bottom of the new

pavement) so that no concrete is permitted to flow

under it. Holes in the expansion joint filler shall be

neatly punched or drilled and the dowels shall fit

tightly through with no gaps in which concrete could

flow. The free end of each dowel (the end not welded

to the basket wire) shall be oiled with a bond breaker

and the expansion sleeve attached immediately prior

to placing the concrete. The expansion sleeve is

required to allow the dowel to slide a distance of 25

mm (1 inch) inside of it.

The Contractor must provide adequate

consolidation throughout the slab depth adjacent to

the joint filler and around dowels.

10.6 Construction Joint

Construction joints are built at the end of each day’s

work or whenever it is necessary to suspend work for

more than 30 minutes. Construction joints in all con-

crete pavements are to be dowelled and perpendicular

to the centerline. Construction joints may be located

at a contraction joint or between contraction joints.

Construction joints are to be formed with a

straight bulkhead with openings provided for dowel

bars and spaced as detailed in the standard drawing

for transverse pavement joints. Construction joints in

reinforced pavement (Item 451) may be located at a

contraction joint or between contraction joints,

provided that they are not closer than 3.0 m (10 feet)

to another parallel joint. In plain concrete pavement

or concrete base (Item 452 or 305), a construction

joint shall not be closer than 1.8 m (6 feet) to another

parallel joint. Construction joints in all concrete

pavements shall be sealed as detailed in the standard

drawing for that type of pavement.

10.7 Checking

The Inspector occasionally should check the width

and depth of joint groves for conformance with the

requirements discussed in this section of the manual.

Special attention should be given to checking depths

of sawed longitudinal joints between lanes placed at

the same time. The limits of areas checked should be

recorded on Form C-119, Inspector’s Daily Report,

for filing in the project records.

23

Chapter 10.0: Sawing and Forming Joints


11.0 Reinforcement

11.1 Purpose

Distributed steel or reinforcement used in highway

pavements generally is in the form of welded wire

fabric or mesh. Its principal function is to hold

together the fractured faces or slabs after cracks have

formed. Adequate load transmission across the crack

is thus assured, and the infiltration of incompressible

material into the crack is prevented. It does not

increase the flexural strength of an unbroken slab.

Like tie bars, steel mesh is designed to withstand

tensile stresses and hold the slab together.

11.2 Handling

Mesh usually is delivered to the job in advance of

paving operations and stored. It should be carefully

stacked and kept clean. Before it is used it should be

inspected to see that it is free from dirt, oil and mud,

which will destroy bond with the concrete, and that it

has not been damaged in shipment or in storage. Any

mesh which has been bent or has welds that have been

broken, should be rejected. If the mesh is repaired, it

should be rechecked before using.

Mesh with rust, mill scale or a combination of

both shall be considered satisfactory provided the

minimum dimensions are not less than specified.

Recent research indicates that tight, scaly and pitted

rust does not prevent bond, but actually improves it.

Therefore, mesh should not be rejected for

rusting unless the rust is so severe that the wire

dimensions are reduced to less than the minimum

specified. The longitudinal wire is designated as a

MW55 or MD55 (W8.5 or D8.5) size and has a

nominal diameter of 8.4 mm (0.329 inch). An MW26

or MD26 (W4 or D4) wire is used transversely and

has a nominal diameter of 5.7 mm (0.225) inches. If

it is suspected that the wire dimensions have been

reduced, the District laboratory should be requested to

check the wire dimensions with a micrometer.

11.3 Condition of Mesh

If mesh is placed along the rough grade or the

shoulder so as to be convenient to the paving

operation, it should not be done so far in advance that

mud will accumulate on it. Care should be taken to

prevent the mesh from becoming badly bent.

If a mesh cart is used on the forms behind a

spreader, the mesh is stacked in piles of the size

carried on the cart at intervals along the grade. These

stacks should be placed on wood blocks or in some

manner kept from becoming caked with mud from the

grade.

11.4 Placing

If the pavement is being placed in two courses, the

concrete for the base layer should be distributed

uniformly on the subbase and then struck off by means

of a mechanical template to the proper depth. The

normal strike off is from 64 mm (2 1/2 inches) to T/3 +

25 mm (T/3 + 1 inch) below the finished surface

(where T is the thickness of the pavement). The strike

off should leave a plane table without voids or high

spots on which to place the mesh. Concrete shall be

24


placed and struck off uniformly to permit placing of

mesh to specified depth without manipulation.

If the mesh is bent, it should be straightened

before it is placed or if it has a gradual bow place it so

the concave side is down. Workers placing steel must

not track mud or dirt into the concrete.

11.5 Tieing

The mesh is to be placed between the forms leaving 50

mm (2 inches) between the ends of the wires and the

side forms, pavement edge, or centerline of pavement.

Reinforcing mesh is normally shipped in lengths of 5.9

m (19 feet) by 3.6 m (11'-8") wide which will fit the

specified joint spacing of 6.5 m (21 feet) for reinforced

concrete pavement with an allowance of 300 ± 50 mm

(12 ± 2 inches) from the center of each transverse

joint. If shorter lengths are provided, transverse laps

shall be 305 mm (12 inches) and mesh sheets shall be

fastened at the edge of the lane and two other

locations.

Usually, mesh is not fabricated for lane widths

greater than 3.6 m (12 feet). Therefore, when placing

pavement lanes in excess of 3.6 m (12 feet) in width it

will be necessary to tie additional mesh to the

standard width sheet. This may be done by tieing

together the outer longitudinal wire of adjacent

sheets. A minimum of four ties should be placed

along the overlapped longitudinal wires to hold the

two sections of mesh in the same plane until the

concrete sets.

If the screeding operation has been done

properly and the mesh placed in flat sheets and tied

properly, there will be no difficulty from the steel

working up into the finishing operations.

25

Chapter 11.0: Reinforcement


12.0 Moisture and Mix Control

Instructions for controlling the proportioning and

mixing of concrete are contained in the Manual of

Procedures for Concrete. The Inspector should

review its contents so that he is familiar with the

details of the production and delivery of concrete for

use in pavements.

26


13.0 Placing and Spreading

13.1 Placing on Grade

Concrete is to be deposited upon the subbase evenly

in a manner that requires a minimum of redistribution.

Even distribution of concrete on the subgrade, or in

each course being placed, is the first step toward an

acceptable job.

13.1.1 Importance of Uniform SpreadThe most even distribution in initial placing will

result in minimum variation in final settlement of the

surface. If concrete is deposited in piles, or

windrows, unequal consolidation may take place

before finishing operation are begun. This never will

be overcome throughout the finishing procedure and

can be the cause of unequal settlement and rough

surfaces after finishing has been completed.

In case of transmit mixer or dump truck

delivery, methods of discharging shall be used that

will spread each batch as evenly as possible. Better

results are obtained when a hopper-type spreader is

used with concrete delivered to the site either with

transit mixer or dump truck.

13.2 Spreading

13.2.1 When RequiredAn approved spreader must be used whenever the

pavement being placed in one operation is 3.6 m (12

feet) or more in width and the amount to be placed

exceeds 8300 m²(10,000 square yards). Concrete

spreaders are powerful pieces of equipment and will

handle heavy accumulations of concrete. However,

this is not reason to permit improper distribution.

13.2.2 HeadThe initial placing of the concrete should be just

enough so that a slight excess is carried ahead of the

spreader as it levels the concrete to a uniform surface

or, in case a spreader is not required, the concrete can

be spread and leveled easily with shovels. Unless this

is done there will be irregular surge past the strike off

of the spreader or past the finishing screed.

This will necessitate excessive manipulation of

the surface in order to obtain specified smoothness

requirements. Excessive manipulation tends to alter

the quality, durability and wear resistance of the

finished pavement.

In addition to these principal precautions in

placing operations, there are some others that should

be observed. Workers should not track dirt or other

debris into the concrete, nor should they walk

unnecessarily on the fresh concrete after it has been

struck off. Boot tracks often are filled with mortar

which will shrink when setting, which may develop

into low spots. Foreign material must be kept out of

the concrete. The incorporation of such items in

concrete also will cause defects in the pavement.

13.2.3 Care at JointsConcrete should be shoveled in place around

expansion joint assemblies. The concrete should not

be dropped directly on joint assemblies from the

delivery equipment but should be gradually spread

27


over them by the spreading machines. If a

hopper type spreader is used, it should not be

positioned over the joint assemblies while concrete is

being discharged. This could result in displacing the

dowel assembly or dowels.

13.3 Vibration

Internal vibration is required for consolidating concrete

for the full width of pavement placed. If internal

vibration is attached to the paving machine, separate

vibration along the forms and around contraction joint

assemblies is not required. However, separate

vibration around expansion joint assemblies and

construction joints shall be a requirement in fill-in

areas not traversed with such equipment. Regardless of

the method of consolidation used the vibration must

be shut off when the machine stops. If it is permitted

to run, rapid segregation of the concrete composition

can occur which may cause weak spots in the slab.

Also, this practice may cause the vibration action to

be picked up by each dowel and result in water planes

and/or soft weak mortar being formed along each

dowel. This seriously reduces the strength and ability

of the concrete to absorb the bearing stress which

each dowel transmits to the concrete under traffic

load, and contributes to early faulting of the joint.

The Contractor is to provide the Engineer a

tachometer or other frequency measuring device to

verify the vibration frequency. The vibration

frequency shall be maintained between 7,000 and

11,000 impulses per minute.

28



14.0 Operation of Transverse Finishing Machine

14.1 Work to be Performed

The work of the transverse screed is an intermediate

step in the process between placing and distribution

of the concrete and the final mechanical finishing.

The work performed by the screed should be as nearly

complete as is possible, so that the operation by any

following equipment need be only a smoothing and

floating process.

As the transverse screed begins work, the

concrete before it must be distributed to

approximately the correct surface level, either by

mechanical concrete spreaders or by hand methods.

The requirements for correct operation of the

transverse screed are the same regardless of the

method of prior distribution, except that local grading

by hand work will be more irregular and will require

more care in the screeding operation.

14.2 Result to be Obtained

The transverse screed must leave the surface with a

uniform texture and screeded to a uniform, correct

elevation for final finishing. If the screed does not

perform this function, good finish cannot be obtained.

Deep or irregular corrugations behind the screed

indicate improper operation.

14.3 Factors Involved

Satisfactory results of operation of the transverse

screed depend upon several critical factors. These

factors must be considered at all times, and variations

in the adjustments or in the operation of the screed

must be made, as occasion demands, to keep the

factors always in balance.

14.3.1 Head-Front ScreedThe head of concrete carried in front of the

forward screed must be maintained at uniform

heights, 100 to 250 mm (4 to 10 inches), and in

uniform quantity across the full width of the lane.

14.3.2 Head-Rear ScreedThe head of concrete carried in front of the rear

screed must be uniform and about 50 to 100 mm (2 to

4 inches) high. The material being moved ahead by

the rear screed should roll, not flow or tear, and the

mix and timing of operations must be controlled to

satisfy this requirement.

14.3.3 Height and TiltThe height and tilt of the screeds must be

adjusted to compact the particular mix being used and

to permit a uniform amount of surge.

14.3.4 Traction Speed and StrokeThe traction speed, screed speed, and length of

screed stroke are controlled independently. They

must be combined in the proper relation to obtain

optimum results. As conditions on the project vary,

these relationships should be varied to produce a

constant quality of result.

14.3.5 Clean RailsThe forms and wheels must be kept clean. If the

wheels ride on an irregular surface, the concrete will

29


show corresponding roughness. The screeds

must be kept clean, so that they do not leave streaks in

the concrete and do not drop lumps of hardened

concrete on the fresh surface.

14.3.6 SurgeThe amount of concrete being carried ahead of

the screeds (both forward and rear) controls the

amount of surge past the screeds for any given mix. If

the head of concrete is too high, an excess will pass

under the screed and an overload will be left for

following equipment. If there is a deficiency of

concrete at any point in front of the screed, a low spot

will develop at that point. If the head varies

continually, the surge will also vary and a wavy or

rough surface will be left. Therefore, a uniform roll

of concrete must be maintained along the front edge

of the screeds to provide a uniform amount of surge.

At the beginning of a day’s work there should be a

small amount of concrete placed in front of the

forward screed to provide a working supply for filling

in low areas. As the work progresses, this

accumulation should not be allowed to build up, but

should be maintained uniformly. If excess builds up,

the excess should be screeded off or a second pass

made.

14.4 General Operation

The Inspector should insist that the work of distribution

and the work of the transverse screeding be

coordinated to give continuous, acceptable results. The

forward screed should compact the concrete without

excessive surge. The rear screed should cut the

concrete off at the top of form level, allowing for a

very small amount of settlement which usually occurs

before the following finisher passes. The difference in

the requirements at the two screeds accounts for the

difference in the size load each should carry.

14.5 Passes Necessary

If one pass of the screed does not result in satisfactory

surface conditions, a second pass is necessary. It is

preferable that preceding operations be controlled so

that a second pass is not required at intermittent

points. If the Contractor elects to use two screeds or

to pass over the entire area twice with one machine,

such a procedure is acceptable. Different amounts of

screeding will result in variable surface conditions

and are to be discouraged.

14.6 Effect of Mix Consistency

Screeds always should work with the screed wearing

plates working directly on the forms. A straight

screed with no tilt will result in a concrete surface at

or below form level, except for surge. Adjustments in

the elevation and tilt of the screeds may be required to

work certain mixes properly. If the mix is extremely

stiff the screeds normally will tear the surface and

leave insufficient mortar for finishing. Under these

conditions the front or first screed should be tilted so

that the forward edge is raised slightly. This will

compact the concrete as the screed passes and force a

small amount of mortar to the surface. With

extremely stiff mixes there likely will be an absence

of surge which, with combined tearing, leaves the

surface below the top of forms. The center of the

screed then should be raised slightly by adjusting end

screed hanger bolts, leaving the end plates to work on

the forms with the remainder of the screed raised.

This will permit the required amount of concrete to

pass the forward screed. The rear screed always

should be straight along the rear edge and work

directly on the forms.

The amount of tilt of the screeds must be worked

out for the particular job conditions. As a starting

30



guide, the following information will be of assistance.

With standard Portland cements and with air

entrained concrete of relatively stiff consistency, less

than 50 mm (2-inch slump), the forward screed likely

will require a tilt of 6 mm (1/4 inch) or less and the

rear screed a tilt of 0 to 2 mm (1/16 inch).

14.7 Relation-Traction of Stroke

The combinations of traction speed and screed motion

to be selected depend on the concrete mix and

consistency and upon the grade or super elevation of

the pavement. With stiff mixes, the screed speed

should be rapid with a long stroke and the traction

should be slow in comparison to more workable

mixes. This provides extra working of the concrete

and will aid in compaction and in providing enough

mortar at the surface for finishing. With more fluid

mixes, the screed action should be decreased, both in

speed and length, and the traction speed should be

increased. This will prevent over working or

excessive agitation of the concrete which might cause

flowing to the low side of the forms, excessive surge

past the screeds or a pooling of wet mortar on the top.

The relation of traction and screed speeds is very

important. In most machines, the controls are

independent and the choice of proper combination can

be made by trial without any difficulty. A change in

speed of either screeds to reaction requires only

shifting of a lever. The change of length of screed

stroke requires a stoppage of work and readjustment

of the screed drive, but this change should not be

required very often unless control of the concrete mix

is poor. Poor control of the concrete mix should not

be tolerated.

14.8 Wearing Plates

The screed wearing plates are rubbing continuously on

the forms or on completed concrete lanes. They are

made of abrasion resisting steel, but may wear rapidly

under the heavy punishment they receive. As they

wear, they have the effect of lowering the entire

center portion of the screed by the amount of wear.

Furthermore, the wear may not be the same for the

full length of screed stroke, and may vary the strike

off elevation of the screed. They should be checked

at the beginning of each job. Adjustments for up to 3

mm (1/8 inch) in wear can be taken care of by

adjusting the screed bolts. When wear exceeds this

amount, the plates should be replaced.

14.9 Care at Expansion Joints

Care should be exercised when operating the finishing

machine over expansion joints to avoid displacing or

damaging the preformed expansion material. Any

method of operation that does not interfere with the

expansion material will be permitted.

14.10 General

Inspectors on transverse screeding work must

remember that the finishing machine is not intended

for heavy duty. The surface left by this work must be

uniform and satisfactory. The ability of the transverse

screed to provide these requirements is available in

the machine. The Inspector should insist that the

operator make full use of the capabilities of the

machine in order to obtain a complete and proper

integration with the entire paving process.

31

Chapter 14.0: Operation of Transverse Finishing Machine


15.0 Operation of Combination Float Finisher

The combination float finisher serves both as a

conventional transverse and longitudinal finisher.

The transverse screeding is accomplished through the

two screeds (front and rear) and the longitudinal

finishing by the suspended finishing pan which rides

on the slab surface.

All phases of good construction practice must be

followed in order to obtain the best finish. Several

points, however, must be adhered to closely in order

that the best possible finish will be obtained when the

machine is used for the final mechanical finishing

operations. These items are described in the

following sections.

15.1 Metering Concrete to Machine

The concrete must be accurately metered to the

machine. Better results are obtained when spreaders

and auxiliary screeds (when used) operating ahead of

the machine leave just enough concrete so that a

uniform roll of 100 to 150 mm (4 to 6 inches) is

carried on the front screed. When this condition does

not exist, the equipment operating ahead of the float

finisher should be adjusted so that such a concrete roll

is obtained.

15.2 Setting Screeds and Float

The screeds and float must be set accurately. Both

front and rear screeds should be set flat. When the

front screed is flat and carries a 100 to 150 mm (4 to 6

inch) roll, it passes sufficient concrete to form about a

50 mm (2-inch) roll on the rear screed. When this 50

mm (2-inch) roll reduces in size, fresh material should

be carried back and placed so that a uniform roll is

obtained. It is essential that the roll in front of the

rear screed be kept uniform for optimum results.

The rear screed cuts off any excess concrete and

leaves the pavement surface at the desired crown and

grade. When set to proper crown without tilt, the

float just makes contact with the surface which it

trowels smooth and free of screed marks.

Occasionally, it is desirable to leave the front of the

float about 2 mm (1/16 inch) when greater

compaction is desirable. This practice, however,

generally leaves deeper transverse marks than are

considered desirable.

15.3 Adjust to Proper Speed

15.3.1 One Pass OperationThe finishing machine is designed primarily for

a one pass operation. If all operations prior to the

pass of the machine are as they should be, it rarely

will be necessary to make more than one finishing

pass with the machine.

15.3.2 Continuous OperationIf the forward speed is adjusted properly, the

machine will move forward at a uniform rate

eliminating frequent stops which cause variations in

the surface. It is true with this machine as it is with

other types of finishing equipment that continuous

operation, without stopping, provides smoother

pavement.

32


15.4 Cleanliness

The machine must be kept clean. The bottoms of the

screeds and the pan must be absolutely smooth.

Accumulations of hardened concrete (or oil and

grease) which might drop on the pavement must be

cleaned off continually. The machine should be

cleaned thoroughly every day.

33

Chapter 15.0: Operation of Combination Float Finisher


16.0 Slip Form Paving

16.1 General

This method of construction permits the placement of

pavement without the use of fixed side forms. In lieu

of forms, the paver vibrates, tamps, compresses and

strikes off the concrete while within the confines of

moving forms of the machine and extrudes the

consolidated concrete slab. Consolidation is such that

the vertical side faces of the slab retain their shape

and position after the passing of the traveling side

forms. Trailing side forms are needed only to protect

the slab edges during hand straightedging operations.

The specifications allow the Contractor the

option of using the slip form or the fixed form method

of pavement construction.

16.2 Subbase

Subbase must be constructed as outlined in the

specifications and in section 7 of this manual.

Stability of the subbase is considered to be critical for

slip form construction. If stability is lacking, the

subbase must be stabilized by added admixes or

angular aggregate particles at the Contractor’s

expense.

The subbase is to be graded to the plan elevation

by a properly designed machine. The track area may

be brought to grade using a form grader, with a

subgrader on crawlers used to grade the area under

the pavement. An automatic subgrader operating

from a preset grade line is considered ideal for slip

form con-struction and does not require the use of a

form grader.

Stabilization in the paver track area to provide

for traction is permissible, provided the area is

scarified after pavement construction to avoid

interference with lateral drainage of the subbase.

Any method of stabilization proposed by the

Contractor should be reported to the Construction

Section for consideration and approval.

16.3 Placing Concrete

An approved slipform paver or combination of pavers

shall be used to spread, consolidate, screed and finish

the concrete in one complete pass of the machine.

The machine shall consolidate the full width and

depth of pavement being placed so as to provide a

dense homogeneous pavement requiring a minimum

of hand finishing. Two machines may be used with

the front one striking off the bottom course for

placement of the mesh. The width of the bottom

course may be 150 mm (6 inches) narrower than plan

width so as not to interfere with the second paver.

The concrete shall have a slump of not more

than 75 mm (3 inches). If the slump exceeds 75 mm

(3 inches), the edges may be subject to settlement

after the forms have passed. Slump less than about 40

mm (1 1/2 inches) may result in an open textured

surface requiring excessive hand finishing.

Therefore, the slump should be maintained between

40 and 75 mm (1 1/2 and 3 inches) for best results.

Good construction results if the paver is

operated with a continuous forward motion with a

minimum of starting and stopping. When the paver

stops, all vibrating tamping and oscillating elements

must stop also.

34


At construction joints at the end of the day’s

production, the pavement may be reduced

approximately 50 mm (2 inches) in overall width.

This allows the Contractor to use an insert just inside

each moving side form to permit the paver to be

positioned at the joint when production is resumed.

The trailing side forms do not bind and spall the slab

edges when the leeway is provided on each side.

The slip form machine is not to be used as a

dozer to push large quantities of concrete piles out in

front. Therefore, some means of depositing and

striking off the concrete must be employed to permit

smooth uninterrupted operation of the paver. The use

of spreader boxes, a concrete spreader or any

technique that will provide a uniform distribution of

concrete is permissible.

16.4 Grade Control

Preset grade lines are required for slipform paving

equipment to assure acceptable riding quality of the

pavement. Preset grade lines may consist of: (1) a

stringline offset from and parallel with the edge of the

pavement; or (2) the compacted and trimmed surface

of the subbase.

If stringlines are used, they may be set on one or

both sides of the pavement and the grade transferred

to the paver through sensors following the grade of

the stringline. A smoother pavement is normally

obtained if two stringlines are used, one for each

pavement edge.

The grade may be traced from the surface of the

subbase by use of skis which electronically control

the grade of the slipform paver. When this method is

employed on one or both side of the pavement, the

subbase should be thoroughly compacted and the

surface grade closely controlled. Skis should be

placed in areas where the subbase is not affected by

any of the paving equipment.

The use of stringlines and subbase surfaces

alone will not assure riding quality. All lines, grades

and controls should be frequently observed to avoid

obvious errors. The electronic controls of the

slipform paving equipment are not capable of sensing

errors in the gradeline and, therefore, will duplicate

errors in grade controls in the pavement surface. In

order to attain the riding quality possible with

slipform pavers, constant attention must be given the

preset grade lines. When a stringline is used, the

stringline should be supported at intervals which will

eliminate sagging of the string under its own weight.

It has been found that supports every 8 m (25 feet)

produce the most desirable results. In addition to the

intervals between supports, the tension in the

stringline must also be taut enough that excessive sag

does not occur.

When slip form paving, inspection should

include checking the pavement edge. Since no forms

are used to screed against or to hold the edge in place,

the edge can slump downward or tilt out. This can

result in an area of lower elevation which will hold

water if pavement is placed against it. The edge of

the pavement shall not vary more than 6 mm (1/4

inch) below the typical section if pavement is to be

placed next to it. A straightedge can be placed

perpendicular to the edge to check transversely. In

addition, the straightedge can be placed longitudinally

at the pavement edge to check in that direction. Areas

which do not meet the tolerance must be corrected

while the concrete is plastic. The outside edge of

pavement, the edge that will not have concrete adjacent to

it, shall not vary more than 13 mm (1/2 inch) from the

typical section.

16.5 Finishing

Diagonal pipe floats suspended from self-propelled

machines have been used successfully to machine

finish slip form pavement without damage to the

unformed edges. They are equipped with a water

35

Chapter 16.0: Slip Form Paving


spray system which applies a fog spray of water.

Such water should always be a fog spray and should

be used only at the start of a finishing pass. With pipe

floats it may not be necessary to hand straightedge the

entire pavement surface. However, a straightedge

should be used periodically to check the pavement

surface.

Edging is accomplished by an attachment to the

machine or the trailing forms. With proper

adjustment, such devices can satisfactorily apply the

specified edge radius automatically.

Some machines trail several sections of forms

while others have no trailing forms. When trailing

forms are employed, they provide protection to the

edges while the surface is straightedged. However,

straightedging should not be confined to the area of

the trailing forms.

Equipment applying the texture and the

membrane curing compound straddle the pavement

the same as the paver and the pipe float. This

equipment rides on the subbase or subgrade.

Membrane machines are capable of covering the

vertical faces, as well as the horizontal surface of the

pavement, in one operation.

36



17.0 Field Checking

17.1 Running Yield

Running yields may be determined at any time during

a pour and provide an easy, accurate method of

checking. To make this, check the amount of

concrete required for one linear meter (foot) of

finished pavement of the width and depth being

placed is computed first. This normally is computed

by the followed formula:

or

In the case of a 7.2 meter wide slab, 255 mm

thick the following calculation would result:

or

In the case of the 24-foot wide slab, 9 inches

thick, the following calculation results:

Once this running yield factor has been

calculated, it can be used to determine the concrete

requirement for any length of slab of the same

dimensions simply by multiplying the slab length by

the factor.

The actual quantity used is easily computed for

any length of slab by multiplying the number of

batches placed by the number of cubic meters (cubic

yards) per batch.

Assume that 1,293 meters of the above metric

example pavement was placed and 345, 7-cubic meter

batches were placed. The running yield calculations

would be as follows:

1,293 m x 1.84 m³/m = 2,379 m³

345 batches x 7 m³/batch = 2,415 m³

2,415 m³ - 2,379 m³ = 36 m³ difference

36 m³ ÷ 2,379 m³ x 100% = 1.51 percent overrun

Assume 4,245 linear feet of the above pavement

was placed and 360, 8-cubic yard batches were used.

Calculations would be as follows:

4,245 linear feet x 2/3 yd ³ per linear ft = 2,830 yd ³

360 batches x 8 yd ³ = 2,880 yd ³

2,880 yd ³ - 2,830 yd ³ = 50 yd ³ difference

50 yd ³ ÷ 2,830 yd ³ x 100= 1.77% overrun

Generally due to wasting over the forms, spillage,

etc., the quantity used will be from 1 to 3 percent

greater than that required. Whenever this relationship

does not occur, immediate steps should be taken to find

the cause.

Overruns may be caused by several factors,

including inaccurate weighing, low subbase, excessive

waste, etc. Similarly, an underrun in concrete may be

37


due to inaccurate weighing, high subbase, loss of

crown, insufficient width of slab, settlement of forms,

etc.

17.2 Pavement Thickness

In order to insure that the specified thickness of

pavement is being constructed, the depth should be

checked periodically. This test is made as follows:

Place metal plates, approximately 125 to 150

mm (5 to 6 inches) square, on the subgrade. These

should be in line and spaced at about 1.2 meters (4-

foot) intervals between the forms or area of pavement

being placed. Sufficient references must be made so

that the plates may be located after the concrete is

placed. After the concrete at plate locations is in

place and the final mechanical equipment passes over

it, a small rod, such as a staking pin, is worked down

through the concrete at plate locations until it touches

the metal plate. The surface of the concrete is marked

on the rod and the rod withdrawn and the depth

measured.

Whenever the pavement is found to be deficient

in thickness all operations and equipment

immediately should be checked and corrected where

necessary, so that the proper slab thickness will be

obtained.

17.3 Crown

Where pavement is placed in single lanes, the

pavement slopes from the low edge to the high edge at

0.016 cross slope and can be readily checked for

transverse smoothness with a string or straightedge. In

this case, checks frequently should be made to insure

that the final pavement surface is as required.

If, however, the Contractor elects to finish the

two lanes of pavement with a crown in the center in

one operation, as when placing 7.2 m (24-foot)

pavement, the center 1.8 m (6 feet) of pavement is

rounded.

If slip form paving is used, the rounding is

optional.

Obviously when the pavement is so constructed,

a straightedge cannot be used to check the final

crown. The crown can, however, be readily checked

using two 76 mm (3-inch) steel blocks and piano wire

as follows:

1. Calculate at 0.6 meter (2-foot) intervals, the

height the pavement surface should be above a

straight line connecting the tops of the forms. For

example in a 7.2 meter (24-foot) pavement with the

high point in the center of the slab these heights are:

Distance from Center Height above Straight Line

meters (feet) millimeters (inches)

3.6 (12) 0 (0)

3.0 (10) 10 (3/8)

2.4 (8) 19 (3/4)

1.8 (6) 29 (1 1/8)

1.2 (4) 38 (1 1/2)

0.6 (2) 48 (1 7/8)

0 (0) 58 (2 1/4)

2. Subtract the values determined in (1) to

establish the distance the pavement surface should be

below a line 76 mm (3 inches) above and parallel to

the line connecting the tops of the forms. In the

example given above these values will be:

Distance from Center Distance below 3-inch Line

meters (feet) millimeters (inches)

3.6 (12) 76 (3)

3.0 (10) 66 (2 5/8)

2.4 (8) 57 (2 1/4)

1.8 (6) 47 (1 7/8)

1.2 (4) 38 (1 1/2)

0.6 (2) 28 (1 1/8)

0 (0) 18 (3/4)

3. Set the blocks on the cleaned forms and stretch

the wire across the slab. Then measure the distance

38



the surface of the slab is below the wire. The

measured distance should closely match those

calculated in (2).

A crown check always should be made at the

start of paving operations to determine that all

equipment is properly set and functioning as it should.

Whenever deviations in crown from that specified are

found, immediate steps should be taken to correct the

situation. Checking crown and adjusting equipment

and operations should continue until the proper crown

is obtained.

It is advisable to make a daily check of crown

throughout construction to determine that changes in

equipment or procedure, which might effect the

crown, have not occurred.

17.4 Recording Checks

The fact that field checks were made should be

recorded on the Inspector’s Daily Report Form C-119.

Any checks found not in compliance shall be cause

for immediate corrective action and should be

followed with rechecks.

39

Chapter 17.0: Field Checking


18.0 Final Finishing

18.1 Importance

Perhaps final finishing is the most important step inthe paving operation, at least from the publicviewpoint, because it determines whether or not thefinal surface meets the tolerance necessary for asmooth riding surface.

Projects using high-strength, quality concreteand the best of modern paving equipment often endup with substandard surfaces, simply because ofcareless work and lack of attention to details duringfinal finishing.

If forms are set accurately, and if all finishingmachines are adjusted and operated properly, thework of the hand finishers will be simplified, but itstill must not be neglected. If finishing machines donot function properly, additional work is required forthe hand finishers to correct surface irregularities andproduce an acceptable surface which complies withthe specifications. The preferred method is to keepthe machines in proper adjustment. In any case, it isup to the Inspector to insist that the finishers doproduce a pavement with the required smoothness andan acceptable uniform final surface texture.

The Inspector should see that the finisherschecks their hand tools before paving operationsbegin to make sure that they comply withspecifications.

18.2 Straight Edging

Straightedges should be tested with a string or a masterstraightedge to make sure they are straight. Thisshould be done daily and tools trued to correct for

wear. They must be rigid enough to remain straight

with no bending while in use. Handles must be 1

meter (3 feet) longer than one half the width of the

pavement. The straightedge itself shall be 3.0 meters

(10 feet) long.

18.2.1 Correcting Minor IrregularitiesAfter the mechanical finishing, while the

concrete is still plastic, minor irregularities and marks

in the surface should be removed with a scraping

straightedge. When necessary, excess water and

laitance should be removed from the surface

transversely by means of a scraping straightedge.

Any such excess should be wasted over the forms.

18.2.2 Type of ToolsA number of different types of straightedges have

been used satisfactorily. They must be strong enough

to maintain a true straightedge and yet light enough to

handle. In some cases they also must be heavy enough

to cut or scrape off any high spots left by the machine

finishing operations. They should be 3.0 meters (10

feet) long to comply with the specifications.

18.2.3 OperationThe straightedge is operated from the side of the

pavement transversely and should be advanced along

the pavement in successive stages. By proper

manipulation it can be used as a float to smooth the

surface or as a cutter to remove high spots.

18.2.4 Use of FloatsLong-handled floats may be used to smooth and

fill in open textured areas in the surface, but this must

40


be done before straightedge finishing. The use

of such floats should be held to a minimum. If open

textured areas persist, it is well to check the aggregate

grading, mix design and the method of placing the

concrete, for a properly proportioned mix should not

require hand floating if the preceding mechanical

equipment is properly adjusted.

No water is to be added to the surface during

this or any other operation.

18.2.5 Longitudinal JointsLongitudinal joints between separately placed

lanes require extra care to assure that a smooth

transition from one lane to the other will result. Good

workmanship is necessary at these joints to obtain

satisfactory results.

Edging on both sides of these joints should be

accomplished using a 3 mm (1/8-inch) radius tool.

Hand finishing and straightedging should be

performed carefully so that each lane will be at the

same elevation.

As a guide the surface of the pavement in the

joint area should not vary more that 3 mm (1/8 inch)

from a 3.0 meter (10-foot) straightedge in both

longitudinal and transverse directions.

18.3 Edging

Edging tools must be inspected to see that they have

the edge radius required. A 13 mm (1/2 inch) radius

is required for the outside edge of the pavement.

Longitudinal joints between separately placed lanes

require an edger with a 3 mm (1/8-inch) radius.

The slab should be edged as soon as the concrete

becomes stiff enough to remain firm without running

back into the groove. The edge first should be cut

with a small trowel and then followed by the edger.

The edging tool should be held flat with the pavement

surface. A trowel should be used to remove the bead

left by the edging tool. Since the final texturing is to

follow edging, this operation must not be permitted to lag.

18.4 Texturing

18.4.1 WhenWhen most of the water sheen has disappeared,

but before concrete becomes nonplastic, the final

surface texture should be applied.

Surface textures for concrete vary with the type

of construction. Finishing methods used must

produce the texture as described in the appropriate

specification item.

18.4.2 How to TextureUnless otherwise specified in the plans, exposed

concrete pavement (451 and 452) are to be textured

by the use of an artificial turf drag or broom drag in

the longitudinal direction immediately followed by an

approved device which will produce a uniform pattern

of grooves in the transverse direction. The turf or

broom drag must produce a uniform, gritty

longitudinal texture. The grooves shall be spaced at

approximately 16 mm (5/8-inch) centers and be

approximately 4 mm (0.15 inches) deep and 3 mm

(0.10 inches) wide. Concrete base pavement (305)

shall have a final surface finish that is a uniform gritty

texture as obtained with a broom or artificial turf drag

in the longitudinal direction.

Artificial turf drag, when used, should have

about 1 meter (3 feet) or more turf in contact with the

surface of the concrete. Such drags give best results

when a weight, such as reinforcing steel, is placed on

top of the turf and its entire width.

Brooms suspended from a machine or truss and

dragged over the pavement surface have provided

satisfactory longitudinal texture. The use of wire tines

for the transverse texture can impart the desired groove

depth and are less likely to build up with mortar.

41

Chapter 18.0: Final Finishing


The reason for the use of broom or artificial turf

drag in the longitudinal direction is to provide a more

skid resistant pavement. The Department has found

that new concrete pavement would lose skid

resistance after one year of service with merely a light

burlap drag prior to tine grooving. Broom or turf drag

will roughen the area of concrete between grooves

which results in a longer lasting skid resistance.

Regardless of the method of texturing, the drag

or broom should be lifted clear of the surface when

not being used.

The surface at the pavement edges should be

dragged in the longitudinal direction when necessary

to remove any tool marks left during edging

operations. Tool marks or other surface blemishes

should not be present on the surface. The surface

should have a uniform texture.

18.5 Station Numbers

The Contractor is required by specifications to stencil

station numbers into exposed concrete pavement each

50 meters (100 feet). The dies used to form the

numbers must be 75 to 100 mm (3 to 4 inches) high

and 6 mm (1/4 inch) in depth. The numbers shall be

placed parallel to the pavement edge and centered 12

inches from and facing right edge of the pavement in

the direction of travel. The numbers should be

impressed following the texturing of the surface and

before curing is applied. If the impression is made too

early, the number will tend to close up and will not,

therefore, be as distinct as desired. The following

information applies to stenciling numbers in a dual

lane divided highway pavement project.

The right edge of a pavement is that edge to the

observer’s right as he stands on the pavement at the

low station and faces toward the high station. The

station numbers in the right pavement of a dual

pavement project then are so impressed in the

pavement that they may be read from a car traveling

on the paved shoulder from the low station towards

the high station or in the normal direction of traffic.

Station numbers also must be stenciled in the

left pavement. However, if the same pattern of

marking stations is followed on the left pavement of a

dual lane divided highway pavement project, the

numbers would be on the pavement edge next to the

median. Therefore, for the purpose of stenciling

station numbers in the left pavement of a dual lane

divided highway pavement project, the right edge of

the pavement shall be considered to be the edge on

the right of an observer as he looks from the high

station on the project towards the low station. The

station numbers then may be read easily from a car

traveling on the paved shoulder in the same direction

as the regular traffic.

Stations from 0 to 9 should include “+000”

(“ + 00”) after the digit. From station 10 on, the

“+000” (“ + 00”) is not necessary.

If concrete shoulders are placed with a traveled

lane, the station numbers should be placed 0.3 m (12

inches) in from the outside edge of the shoulder and

facing the pavement.

42



19.0 Curing

Curing is the treatment or protection given concrete

during the hardening period.

Proper curing consists of keeping the concrete

moist and warm to insure adequate hydration of the

cement and to protect concrete from early shrinkage

due to changes in temperature and/or loss of moisture

before it has developed sufficient strength to resist the

resulting tensile stresses.

19.1 Value of Adequate Cure

It is extremely important to provide adequate curing

during the first few days, with the first few hours

being most important to obtain a strong durable

surface. Strength loss due to lack of moisture during

this

period is difficult to regain even with subsequent

curing.

Any one of the several methods of curing

permitted will give satisfactory results if correctly

accomplished. One method may be used throughout

the entire curing period, or it may be considered

better to use a combination of two methods, initial

and final.

Curing should begin as soon as the texturing

process is completed, providing that the finished

surface does not have free water on the surface.

19.2 Effect of Variable Weather

During windy, hot, dry weather it is very important that

the finishing be completed rapidly and the curing be

placed before the surface dries out to the extent that

plastic shrinkage cracks develop. These cracks never

can be sealed, and they also are an indication that the

surface may have been depleted of the necessary

water to properly complete the chemical reaction of

hydration.

Water curing may halt this shrinkage cracking,

but even the addition of more water will not correct

the cracking once it occurs.

In cold weather, the concrete may continue to

bleed after finishing. Care should be taken in placing

any type of curing under these conditions so that the

surface will not be marked. The minimum period for

curing is 7 days, unless specimen beams have attained

a beam strength of 4.2 MPa (600 psi). During cold

weather, concreting the pavement shall be protected

from freezing temperatures until beams attain a

strength of 4.2 MPa (600 psi).

Prior to application, the curing material should

be inspected to assure that it meets specification

requirements. This also applies to any equipment used

in the application.

19.3 Types Permitted

Liquid membrane curing compound is the most

popular method of curing. However, water curing,

waterproof paper, and polyethylene sheeting

are acceptable methods for curing pavement

concrete.

19.4 Membrane Curing

19.4.1 General CommentMembrane materials shall meet specification

requirements and be applied at the minimum rate of 1

43


liter per 3.7 square meters (one gallon per 150

square feet) for Items 451, 452 and 453. Concrete

base, Item 305, shall be treated at the minimum rate

of 1 liter per 4.9 square meters (one gallon per 200

square feet). Exposed concrete with a grooved (tined)

surface requires more curing compound than base

concrete due to the additional surface area caused by

the grooves as opposed to only turf drag or broom

drag finish on the base pavement.

If properly applied, these membrane compounds

prevent evaporation and the retained water provides

excellent curing. Therefore, the principal caution that

should be exercised is to make sure that the specified

rate of application is adhered to and the curing

compound is applied evenly so that a uniform

thickness of membrane coating is obtained. If this is

not done, the quality of concrete will be affected.

White pigmented compound is the only

membrane acceptable on paving projects. This has an

advantage over clear type compounds in summer

construction in that it provides a coating that reflects

heat from the surface and thus decreases heat

absorption in the pavement and the tendency for

transverse cracks to develop in forenoon pours. In

addition, its white color permits visual inspection for

uniform coverage.

19.4.2 How to ApplyOn uniform width slabs application of the curing

compound is made by a power driven mechanical

sprayer which rides the forms or straddles the

pavement if the slipform method is used. Hand

operated sprays are used on sections of variable width

and on the pavement edges after form removal.

The white pigment used in the membrane acts as

an abrasive which tends to enlarge the apertures of the

spray nozzles and to reduce the efficiency of pumping

equipment. Equipment used to apply membrane should

be cleaned frequently and checked to see that it is

providing a uniform protective covering.

19.4.3 Care and StorageCuring compounds especially pigmented ones, tend to

separate during storage. It is important that the material be

stirred thoroughly prior to application in order to obtain a

uniform product and to avoid wastage by leaving heavier

fractions of the compound in the drums. Drums are equipped

with internal paddles for stirring the material to mix the

pigmented compound. A crank is attached externally to a

shaft on one end of the drum to engage the paddles. Drums of

curing compound stored for any length of time should be

placed in storage upside-down so that when they

are reversed prior to use more thorough mixing will

result.

19.4.4 TimingAccurate timing of application is most

important. Membrane never should be sprayed on a

surface until all free water has evaporated and the

concrete has lost its sheen. If membrane is placed on

free water, it tends to float with the result that when

the water disappears the membrane will craze or crack

and peel from the surface. Whenever the texture of

the surface is marred by the application, the concrete

either is too wet to too green, and the application

should be delayed until the membrane may be applied

without disturbing the textured finish.

Any membrane disturbed by foot traffic or by

any other cause should be corrected immediately by

making a second application of the curing compound

with a hand sprayer.

At the close of paving each day, a check should

be made of the number of drums of membrane curing

compound used. This quantity should be checked

against the square meters (square feet) of pavement

44



placed to assure that minimum application is

achieved. This check shall be recorded on the

Inspector’s Daily Report, Form C-119 and filed in the

project records.

19.5 Curing with Paper orPolyethylene Sheeting

This method employs the use of waterproof paper or

polyethylene meeting specification requirements

(705.05 and 705.06). These materials are to be placed

on the concrete as soon as possible after finishing

without marring the surface and are to be left in place

for the full curing period.

19.5.1 Inspection of SheetThe advantage of this curing method is that no

sprinkling or other attention is necessary after

placing, except to make sure that it is anchored

against blowing off by wind and that holes or torn

areas do not occur. The blankets should be inspected

daily during use. Before being reused, small holes or

breaks should be repaired in satisfactory manner.

19.5.2 Proper PlacementThe blankets should be placed so as to cover full

width of lane and lapped at least 0.3 m (12 inches).

When forms are removed, edges should be completely

covered. This may be done by turning down the edge

of the blankets or narrow strips pulled out from under

them. These narrow strips are placed on the concrete

before main sheets are laid.

19.5.3 PrecautionsThese blankets never should be dragged over

fresh concrete and should be placed so as not to mar

surface.

One of the principal precautions in this method

of curing is to make sure edges along forms are sealed

so that there is no possibility of air getting under the

curing material. This is important for two reasons: (1)

unless the seal is adequate, air can circulate over the

pavement which will dry out the surface and result in

inadequate curing; and (2) heavy winds will get under

the blankets and rip them off leaving the pavement

without any curing at all.

19.6 Water Curing

19.6.1 TypesVarious methods of water curing are permitted

by the specifications. These methods include burlap

cloth, waterproof paper or polyethylene sheeting.

These methods are used very infrequently and

therefore are not discussed in detail.

19.6.2 Moisture ControlIf the Contractor should elect to use one of the

water curing methods, his operation should be checked

closely to assure that the curing is done in accordance

with specifications requirements. Make sure that the

pavement is wet at all times. This type of curing

requires constant checking throughout the curing

period.

45

Chapter 19.0: Curing


20.0 Work to be Done Later

20.1 Form Removal

The presence of forms during the early curing protects

the pavement edges against damage and also serves

as a curing method for the pavement edges.

20.1.1 When to Remove FormsDuring warm weather, the common procedure is

to remove the forms approximately 24 hours after the

concrete is placed. During cold weather, it may be

advisable to leave forms in place for a longer period.

In any event, forms should not be removed until the

concrete has attained sufficient strength to prevent

damage to the concrete surface or breaking of the

edges during removal.

20.1.2 How to Remove FormsThe method used to remove the forms should be

such that the concrete pavement will not be damaged.

In addition, the Contractor should be encouraged to

use a method which will not bend or otherwise

damage the forms.

Pin keys first should be loosened, form joint

locks unfastened and nuts removed from end of hook

bolts (single lane paving). Pins then should be

removed from their sockets using a direct vertical lift

without any pressure toward the concrete. The

necessary action to exert the vertical lift should be

from the forms or the ground outside forms. If any

equipment is used to pull pins which may ride on the

concrete, care should be taken to assure that no

pressure is on the concrete other than the weight of

the equipment.

After pins are removed and other preliminary

work finished, light blows with a hammer or careful

prying on base flange may be used to separate forms

from concrete. Prying against the edges of concrete

with bars to break forms loose never should be

permitted.

20.1.3 Care NecessaryThe method used to move forms away from

concrete should be such that each form section will be

pulled horizontally away from edge before it is lifted.

Particular care with regards to this action is necessary

when forms with keyways are used.

20.2 Edge Patching

20.2.1 Inspection of EdgesWhen forms have been removed, edges should

be checked immediately and honeycomb areas

filled.

20.2.2 Repairing HoneycombMortar should be used to fill all honeycomb

areas. Inspections should be made of filled areas to

make sure the entire areas are tightly packed and

struck off flush with surface of the pavement

edge.

20.2.3 Cleaning at JointsJoints should be checked to make sure the ends

are cut through the edges and no concrete is left in the

grooves or around joint materials. Sawed joints should

46


be cut through the pavement edge so that vertical

cracking is assured and preformed compression seals

can be installed easily.

20.2.4 CuringCuring should be applied to edges just as soon as

forms have been removed and patching and cleaning of

joint ends has been completed. This will assure

satisfactory curing as well as preventing the loss of

water necessary for hydration of the cement.

20.3 Joint Sealing

20.3.1 GeneralTransverse and longitudinal joints are sealed to

prevent infiltration of incompressible material. Sealing

also limits entrance of surface water to the subbase.

Pavements contract or shrink when temperatures

drop, thereby causing joints to open. When

temperatures rise, pavements expand and joints close.

The presence of incompressible material prevents the

joint from closing during expansion and subjects the

concrete to compressive stresses. Proper sealing

prevents intrusion and permits joints to perform as

intended during movement of the pavement slab.

20.3.2 When to SealSealing should be done as soon as is feasible

after joints are sawed. All joints must be sealed before

the pavement is opened to traffic. Approval may be

granted upon request to place temporary material to

protect the joint opening during use by construction

traffic.

20.3.3 Cleaning JointsPrior to filling, all joints must be cleaned.

Cleaning consists of operating a saw blade backward

through the saw groove to remove all pebbles, trash,

dirt, etc. Any other operation which satisfactorily

cleans the groove is permissible. The final step in

cleaning shall consist of blowing out the joint opening

using compressed air or by a jet of clean water.

20.3.4 Expansion JointsExpansion joints must be clean for the full width

of the expansion material, and the top of the

expansion material must show over its entire area.

The presence of any concrete around the expansion

material will prevent free compression of the joint

material and may cause spalling along the joint when

the pavement expands.

20.3.5 Joint SealersPreformed compression joint seals are required

in transverse contraction and construction joints in

451 pavements and most 452 pavements. Seals should

be checked to assure they meet specification

requirements (705.11) and are the width specified in

the standard drawing. Installing equipment should be

inspected to make sure it is in good working condition

and is capable of installing the size of sealer

specified. Contraction joints in concrete base are

sealed with a hot applied material meeting the

requirements of 705.04.

Hot applied joint sealer (705.04) or performed

compression joint seals (705.11) may be used for

sealing longitudinal joints in plain or reinforced

pavement if joints are sawed or hand formed. Since

the hot applied sealer requires heating, frequent

checks should be made to avoid overheating to a

temperature higher than the manufacturer’s

recommendation. Check samples shall be taken daily

but should not be taken after a long period of heating.

These samples are sent to the Laboratory.

Longitudinal joints in Item 305, concrete base do not

require sealing.

20.3.6 Condition of JointJoint walls must be inspected just ahead of filling

to make sure that they are dry and thoroughly clean. It

is essential that the walls be in this condition if the

47

Chapter 20.0: Work to be Done Later


sealer is to function properly. If the sealer fails to

adhere to the concrete, water and foreign material will

filter into the joint.

20.3.7 Sealing OperationWhen using liquid sealing compounds, pouring

should be done in such a manner that complete filling

from the bottom of the joint slot to approximately

level with the surface of the pavement is assured. It is

a waste of material and poor workmanship to use a

filling method which leaves a smear of sealing

compound on each side of the joint opening. With

some compounds it may be necessary to fill the joint

in several applications. Workers should not allow the

sealing compound to spatter or drip onto the adjacent

pavement.

If the joint is filled too fast the sealing material

will run to the low side. When using hot poured

compounds they may flow out of the joint at the edge

of the pavement if some method of plugging the edge

is not used. A satisfactory plug can be provided by

any one of the following methods:

1. A ball of mud pressed over the end of the

joint.

2. A small piece of roving jute pressed vertically

into the joint end, flush with face of pavement

edge.

3. A small piece of masking tape placed over

the end of joint.

The surface of the hot applied sealing material will

rise as the temperature increases causing the pavement

to lengthen and the joint to close. Conversely, the

surface will fall as the temperature decreases,

contracting the slab and causing the joint to open.

Filling then should be such that the surface of the hot

applied sealing material will be approximately level

with the pavement surface when the pavement

temperature is about 21C (70F).

Never over fill a joint to the extent that a bump

will be produced at the joint. Such a practice is a

waste of material, creates an unsightly condition, and

affects the riding quality of the finished pavement.

The bumps created by the excessive material will be

readily noticeable to the traveling public from a

smoothness standpoint, as vehicles pass over each

joint.

When placing preformed compression seals in

contraction and construction joint seals should be

installed by machine or by hand methods in such a

manner to avoid stretching the seal excessively. A

maximum elongation of 5 percent should be enforced

during installation. If hand methods are used, seals

that are nicked or cut should be removed and

replaced. An approved lubricant adhesive should be

used to aid in placing the compressed seals into the

joint opening. The seals should be placed so that they

are approximately 6 mm (1/4 inch) below the level of

the pavement surface.

20.3.8 Removal and Repair of UnsatisfactoryPoured Sealer

Prior to final acceptance of the pavement any

unsatisfactory seal should be removed and replaced.

All low spots in sealing compounds must be brought

to the desired level, and any high spots should be cut

off and the excess material removed.

48



21.0 Hot Weather Construction

21.1 General

Specifications do not cover precautions necessary for

placing concrete during hot weather. However, when

high air temperatures, low humidity and winds are

encountered during concreting operations adjustments

must be made in order to assure quality. Any one of

these factors or combination of them speeds up the

rate at which concrete hardens. High temperatures,

especially when accompanied by wind and low

humidity tend to cause a rapid loss of moisture from

the surface of the pavement resulting in early setting

and a reduction in time allowed for finishing.

21.2 Adjustments

In order to counteract the adverse effects of hot

weather, it is necessary to control the temperature of

the concrete mix. Lowering the concrete temperature

to 24C (75F) or below will offset the effects of hot

weather. Selection of a cool water supply is the most

effective means of lowering the mix temperature.

Sprinkling of coarse aggregate stockpiles for moisture

control also aids in controlling the mix temperature.

21.3 Slump

It is a good practice when form paving to maintain the

slump of the concrete near the top limit during hot

weather. Increasing the slump delays the stiffening,

thereby making more time available for the finishing

operations. It is good practice to have any additional

water added at the job site thoroughly blended into

the mix to provide workability.

The use of water on the surface during finishing

results in an increase in the water-cement ratio and

washes out the entrained air in the concrete at the

surface. Needless to say, both of these changes

adversely affect the durability at the surface. The use

of the whitewash brush has probably been the cause

of the majority of scaling occurring in concrete

surfaces. Therefore, the use of water on the surface

during finishing shall not be tolerated.

21.4 Fog Spraying

Under extreme drying conditions mixing water may

evaporate quickly from the surface of the concrete.

This water may be restored by applying a fog spray of

water on the surface, provided the surface has been

completely finished and will not be screeded or

straightedged. This provision should be controlled

carefully and should be the exception rather than the

rule.

21.5 Admixtures

Use of an approved set retarding type admixture may

be desirable in hot weather to retard the setting time

thereby providing more time for finishing. Project

personnel must be aware that a water reducing

retarding admixtures (705.12, Type D) is required in

the concrete (for any concrete usage) if the concrete

temperature exceeds 24C (75F). The use of this

49


admixture will result in less slump loss and result in

high strength concrete. Admixtures for accelerating

the set will be permitted only when provided for in

the contract or upon the written permission of the

Director.

21.6 Rain

An ounce of prevention is worth a pound of cure. If

the pavement is protected, much time and expenditure

in corrective work can be avoided. A roll of

polyethylene sheeting on the finishing machine can be

quickly unrolled to protect large areas of pavement

and corrective measures can be avoided. When the

concrete has not been protected and has been

damaged by rain, increased attention to corrective

measures will be necessary to obtain durable concrete.

Concrete which has been exposed to rain will

have some mortar or paste washed from the surface.

The surface usually has a sandy appearance when the

cement paste is removed. In addition, it will have a

speckled or spattered appearance. Quality can be

restored to the surface by several methods.

If the surface has not been machine finished, it

should be screeded with the machine. This screeding

will eliminate the sandy texture and force grout to the

surface. For a surface which has been machine

finished, the machine may be used to make a single

pass over the area affected, or the surface may be

dragged with the burlap to remove the sand and work

grout to the surface. The burlap drag may have to be

used for several passes to restore the surface finish.

Pavement which has been damaged by heavy

rain should be reworked with the finishing machine, if

the concrete has not taken its initial set. If it has, the

burlap drag alone should be used repeatedly until the

surface has been corrected.

When correcting damage to newly placed

concrete surfaces, the excess surface water must be

removed. It definitely should not be worked into the

concrete. Cement should not be placed on the surface

in an attempt to restore cement paste washed away by

the rain. Such a practice is detrimental to the concrete

rather than helpful.

When a rain persists for a lengthy period of

time, it will be necessary to remove any protective

covering to finish and texture the concrete before it

stiffens and sets. After this has been accomplished the

concrete may be recovered. Membrane curing should

not be applied when the surface is wet and may be

delayed until paving is resumed. If a polyethylene

sheeting is used as a covering, curing may be delayed

indefinitely provided the sheeting is maintained in

accordance with the specifications. However,

membrane curing eventually should be applied to

provide a surface uniform in appearance.

If rain damages the curing membranes, the

surface should be resprayed after the excess water has

dissipated to restore the impervious covering and

retain moisture necessary for curing.

Concrete subjected to rain can be restored to its

original quality provided attention is given to the

details mentioned above. The usual difference

between a rain damaged pavement that is satisfactory

and one that is undesirable is that the finishing crew

did not quit but persevered until satisfactory results

were obtained.

If, for any reason, measures taken by the

Contractor to produce a surface that meets

specifications are unsuccessful, the affected portions

of the pavement must be repaired or replaced to

comply with contract requirements.

There is equipment available that can groove the

transverse texture into pavement that does not have

adequate texture. The equipment must meet the

requirements of 451.122 and be approved by the

Engineer.


50


22.0 Cold Weather Construction

22.1 General

During cold weather, provisions must be made to

prevent concrete from freezing until it has attained

adequate strength. Concrete which has been frozen

before gaining sufficient strength may be damaged

permanently and may never achieve the design

strength. Therefore, it is necessary to protect the

concrete from freezing temperatures during curing in

order to prevent damage and to obtain the design

strength.

The temperature of the concrete and the

surrounding air directly control the rate of hardening of

the concrete. When these temperatures decrease, the

rate of hardening decreases. The rate of hardening

ceases at the freezing point. If the concrete is

maintained just above freezing, it will not be damaged.

However, it will require a lengthy curing period before

it will harden and gain strength sufficient for removing

forms. Under these conditions it is necessary to provide

heat to the concrete so that it will harden and gain

desired strength within seven days.

The Contractor is responsible for protecting

concrete during cold weather. If damage might possibly

occur, the surface shall be protected by any means that

prevents the concrete from freezing and retains the heat

of hydration.

22.2 Adjustments

In order to control the rate of hardening and gaining

strength it may be necessary to control the temperature

of the concrete being placed and to protect the concrete

to retain the heat of hydration during curing. If the air

temperature is 2C (35F) or below when concrete is

being placed, the concrete shall be heated to a

temperature of from 10C to 27C (50 to 80F) when

placed.

Heating mixing water is the most effective way of

heating the concrete. Aggregate may be heated, if

necessary, in addition to the water. The heated water

and aggregate should be introduced into the mixer

before the cement, so that the temperature is reduced

before cement is added to avoid the possibility of a

flash set. One further precaution is to delay the

introduction of the air-entraining agent until the

temperature has been reduced, because hot water

tends to reduce its potency.

The subgrade or subbase and forms shall be free

from frost when concrete is placed. Covering these

areas usually will prevent frost and avoid delays.

22.3 Admixtures

Any request to incorporate an accelerating admixture

during cold weather construction shall be submitted

and approved as outlined in Sec. 21.5.

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23.0 Job Control Testing and Sampling

23.1 Tests

Concrete for use in pavements must meet specified

requirements for air, slump and yield. Tests must be

conducted to check for compliance with these

requirements. The Inspector will conduct these tests

after the concrete has been delivered and deposited on

the subbase. The test results must be within the

following limits:

Air 6 ± 2 percent

Nominal Slump 25-75 mm (1 to 3 inches)

Maximum Slump 100 mm (4 inches)

Yield ± 1 percent

If tests indicate the concrete is not within these

limits, immediate adjustments must be made.

Production should be stopped and check tests made to

confirm noncompliance of the original tests. Concrete

that does not meet specification requirements shall

not be permitted to be used unless adjustments can be

made to correct the deficiency. The fact that concrete

has been produced and transported to the project does

not justify its use unless it conforms to requirements.

Insufficient air may be corrected by the addition

of an air-entraining agent and remixing to generate

additional air. Variations in yield should not be cause

for rejection; however, immediate adjustments must be

made in the batch weights and must be followed by

additional yield tests until conformance is obtained.

Slump may be increased by the addition of water

provided it remains within the above limits. If slump is

excessive the concrete should not be used.

23.2 Sampling

All material being used in the production of concrete

shall be sampled, tested and approved before being

used. Material that has not been sampled before

delivery to the project must be sampled and submitted

for testing. Such material must not be used until

approval has been given by the Laboratory. Sampling

shall be done in accordance with the specifications

and as outlined in Manual of Procedures for

Concrete.

23.3 Cylinders

Cylinders are not required for pavement concrete.

However, if for some reason cylinders are desired,

they should be cast from concrete obtained at the

paving site and are to be made in accordance with the

Manual of Procedures for Concrete. Cylinders are to

be shipped to the Laboratory on the fourth day after

casting where they are tested for compressive strength

at 28 days of age.

23.4 Beams

Beams are required for each 6500 m2 (7,500 square

yards), or fraction thereof, of pavement placed each

day. Instruction for making and testing beams are

found in the Manual of Procedures for Concrete.

Beams are tested at the project by the project

personnel.

The completed pavement may be opened to

traffic, including construction traffic, after 7 days have

52


elapsed. The pavement may be opened to traffic after

5 days provided a beam strength of 4.2 MPa ( 600

pounds per square inch) has been attained. If it has

been determined that it will be necessary to open a

portion of the pavement in fewer than 5 days, high

early strength concrete shall be used, and the

pavement may be opened to traffic after 3 days

provided the test beams attain a strength of 4.2 MPa

(600 pounds per square inch).

Beams normally are tested at 5 and 7 days. If

results are not needed before the end of 7 days, only

one beam break is necessary. This break should be

made at the age of 7 days.

The maximum capacity of the beam breaker is

6.7 MPa (1,000 pounds per square inch) and is

marked on the beam breaker dial. The capacity must

not be exceeded. Beams that do not break when loaded

to the capacity of the breaker should be recorded as

>6.7 MPa (>1000psi) or whatever the unbroken

strength was when the test was stopped, such as 5.9

MPa + (850psi +) for example.

A slump, air and yield test shall be made each

time beams are cast. Concrete for these tests shall be

obtained from the same batch of concrete as that used

in casting the beams.

23.5 Records

Results of air, slump and yield tests are to be

recorded on the Concrete Inspector’s Daily Report as

outlined in the Manual of Procedures for Concrete.

Results of compression tests on cylinders

submitted will be reported by the Laboratory in the

Construction Management System (CMS) under Test

Data Reports.

Results of flexural tests on beams are to be

recorded in the project records.

53

Chapter 23.0: Job Control Testing and Sampling


24.0 Pavement Cores

24.1 General

The Laboratory will remove cores from the completed

pavement to check the pavement thickness in

accordance with 451.16 of the specifications. A core

is taken at random for every 1,650 square meters

(2,000 square yards) of pavement. Locations for

random cores are determined by the Laboratory

whose personnel remove, measure and report

thickness measurements.

24.2 Cooperation

Project personnel are requested to cooperate by

providing assistance as needed to obtain the required

cores. Since the Laboratory technician is not

authorized to take extra cores, such requests

must be made through the District or to the

Laboratory.

24.3 Filling Holes

Specifications require the Contractor to fill all core

holes using the same concrete used in constructing the

pavement. Therefore, the Inspector shall check for

compliance with this requirement.

When filling the core hole, the surface should be

damp and should be painted with a grout consisting of

cement and water having the consistency of a thick

paint. Stiff concrete should then be rodded into the

core hole before the grout dries. The surface should

be struck off and curing membrane applied to provide

curing essential for a durable replacement.

24.4 Measurements

Cores are measured in the field by the Laboratory

technician so that additional cores required may be

obtained at the same time if a thin core is

encountered. Cores are transported to the Laboratory

where they are measured in accordance with

AASHTO T 148.

24.5 Records

If the measurements indicate a deficiency resulting in

a price adjustment, a teletype will be sent by the

Laboratory to the District. A copy of this teletype

should be forwarded to the Engineer and should be

considered when reporting pay quantities for progress

estimates.

After cores are measured they are tested in

compression. After these results are obtained, the

Laboratory will enter the thickness and compressive

strength into CMS. The information will then be

accessible by project personnel.

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25.0 Surface Smoothness

25.1 General

The surface of the completed pavement shall be

cleaned and tested for smoothness by means of a

surface testing machine. Testing shall be done after

the final curing of the pavement. A profilometer is

used to detect and mark the surface variations which

are in excess of the allowable tolerances. For

pavements where the degree of curvature is less than

8 degrees or grades are less than 6 percent, the

tolerance is 3 mm in 3.0 m (1/8 inch in 10 feet). For

ramp pavements and for those pavements that exceed

the 8-degree curvature or 6-percent grade, the

tolerance is 6 mm in 3.0 m (1/4 inch in 10 feet).

Normally two lines, one in each wheel path, are

checked in each 3.6 meter (12-foot) lane.

Profilometers are assigned as outlined in

Directive DH-30C to serve all 12 districts.

25.2 Corrective Work

Surface variations indicated by paint applied by the

profilometer shall be ground off to within tolerance in

accordance with 451.121. This section requires the use

of diamond grinders. Bush hammering, carbide tipped

grinders or any method that may damage the bond of

the aggregate or shatter the aggregate shall not be

permitted. After diamond grinding, transverse

grooving with diamond grooving equipment must

leave the final surface in conformance with 451.09.

Equipment is available commercially to correct

surface variations and provide adequate texture. If

unfamiliar equipment is proposed for use, a check

should be made with the District office to ascertain if

the equipment is acceptable.

A 3.0 meter (10-foot) straightedge should be

used to check for compliance when corrective work is

in progress. The straightedge should be used also to

determine the transverse limits of the area to be

corrected. Usually variations extend beyond the wheel

path and may require diamond grinding and grooving

the entire width of the lane. Only by checking with a

straightedge can this determination be made.

Areas which are low should be corrected by

grinding on each side until within tolerance. If these

areas cannot be corrected by grinding, they shall be

repaired or replaced to the satisfaction of the Engineer.

25.3 Records

The Inspector assigned to this corrective work should

record the limiting stations of work satisfactorily

performed each day. This data should be recorded on

the Inspector’s Daily Report, Form C-119 and also

entered in the Daily Diary in CMS.

55


26.0 Measurement

The plan quantities as adjusted for changes, errors and

deviation in excess of allowable tolerances is the

method of measurement. The length of the roadway is

checked at one time or another during construction and

should serve as the length to be used in determining

pavement quantities. This measurement should be a

matter of record. The width of pavement is spot

checked daily during routine job control and assures

that the specified width is obtained. These length and

width measurements should be checked against those

used in the calculations to assure that plan quantity is

correct. Pavements such as ramps, intersections,

entrances and exits to interchanges which have

variable width shall be measured to determine if the

plan calculated area is correct. If the plan quantity is

in error, the quantity for payment must be calculated

using the actual dimensions measured.

Any changes in plan that involves concrete

pavement quantities must be shown on the form used

to document the final pay quantity. Also, any areas

found to be deficient in thickness must be indicated

on the form and adjustment made in the pay quantity.

56


27.0 Concrete Pavement Repairs

During the life of concrete pavement, it sometimes is

necessary to make repairs to arrest progressive

deterioration and to maintain serviceability. Timely

repairs will restore quality and provide the rideability

and life expectancy for which the pavement was

designed.

Problems may occur at various stages of the

pavement life and it is important that they be

corrected as the need arises. Often, corrections are

necessary during construction and these repairs must

be of the highest standard if the anticipated pavement

life is to be realized. This subject is covered here to

establish a standard procedure and to provide uniform

application for repairs made prior to completion of

the construction contract. These standards also will be

applicable at any time throughout the pavement life.

Generally, concrete pavement repairs are classed

as full-depth pavement replacement and thin-bonded

patching. Full-depth replacement will apply when the

damage is more extensive than surface scaling or

spalling and necessitates removal and replacement for

the full depth of the slab. Thin-bonded patching

applies to surface scaling and spalling, spalling at

edges and joints, and other surface deterioration that

does not extend below the pavement mesh. Thin-

bonded patching also is applicable for similar

deterioration on bridge decks and especially for

spalling associated with insufficient cover over the

top mat of reinforcing. Excellent results have been

obtained for correcting the last mentioned condition by

removing concrete from below the steel and forcing the

steel to a lower position before placing the patching

concrete.

Compliance with all the provisions of the

following standards is necessary to assure durable

repairs and to restore the quality of the facility

permanently.

27.1 Full Depth PavementReplacement

Full depth pavement repairs, when required prior to

acceptance of a new concrete pavement or when

required by a rehabilitation contract, are constructed

in accordance with Item 255, Full Depth Rigid

Pavement Removal and Rigid Replacement. When

this specification is called for, Standard Construction

Drawing BP-2.5M (BP-2.5) entitled Rigid

Replacement shall also apply to the work.

The basic process of full depth repair includes

the following:

1. Full depth diamond sawing

2. Pavement removal

3. Compaction of subbase

4. Drilling dowel bar holes

5. Grouting dowel bars and tiebars

6. Placing, finishing and curing concrete

7. Sealing of joints

27.1.1 Pavement SawingThe limits of the areas to be repaired are marked

by the Engineer. The minimum longitudinal length of

a repair is 1.8 meters (6 feet). All pavement repairs are

normally the full lane width unless otherwise detailed

by the plan.

57


The existing pavement is sawed full depth at the

limits established by the Engineer with a diamond a

saw blade. All diamond saw cuts are perpendicular to

the centerline of the pavement lane. Normally, the

existing concrete pavement thickness is given in the

plan. There may be older projects where the existing

pavement was built thicker than specified in the new

repair plan. Concrete sawing and removal depths may

be as much as 25 mm (1 inch) greater than indicated

on the repair plan without additional compensation to

the Contractor.

If there is an existing asphalt overlay on the

concrete pavement, the Contractor may elect to saw

full depth through the asphalt and the concrete.

Depending on the thickness of each material, the

Contractor may not be capable of sawing through

both courses and may elect to make an offset saw cut

through the asphalt course and remove enough asphalt

to allow a diamond saw to saw full depth through the

concrete pavement. If the Contractor elects to make

offset cuts to facilitate the removal, they will not be

measured for payment. Only full depth saw cuts that

are made at the limits of the removal are measured for

payment. Intermediate saw cuts made by the

Contractor to facilitate removal by the lift out method

will not be measured for payment.

During hot weather, it may be necessary for the

Contractor to saw only at night or morning when

cooler temperatures prevail. Concrete pavement heats

up and expands as temperatures rise during hot

summer days. Diamond saw blades can be pinched

and locked up during sawing by the pavement slabs

due to the pavement expansion.

27.1.2 Pavement RemovalRemoval of the concrete follows the full depth

sawing operation. In order to not disturb the base

under the pavement and to minimize the damage to

the adjacent pavement which is to remain, the lift out

method is required. Holes are drilled within the

removal area and lift pins are inserted. The slab or

portion of the slab is then removed by lifting the slab

vertically with a crane or backhoe. After lifting, loose

debris left behind is removed by hand methods. The

pavement removed is disposed of in accordance with

Item 202. Intermediate sawcuts within a longer slab

replacement are not measured for payment.

The use of a pavement breaker and backhoe for

removal is not permitted unless the Engineer

determines that the lift out method is not practical

because of extensively deteriorated pavement,

existence of bituminous full depth repairs or old

concrete pavement repairs which are extensively

cracked and deteriorated. There will be no additional

compensation for removal of the pavement by

pavement breaker and backhoe.

Regardless of the method used to remove the

pavement, if the pavement to remain is damaged by

the sawing or removal operations, an additional full

depth diamond saw cut is required full width of the

lane or lanes at a distance from the first cut that will

encompass the damaged pavement. The additional

pavement repair area and the additional saw cut is not

measured for payment.

After pavement is removed from the area to be

repaired, if the face of the remaining pavement is

deteriorated on the bottom to a height greater than 1/4

of the pavement thickness an additional saw cut shall

be made. The additional saw cut shall be made 305

mm (12 inches) back from the original saw cut. The

additional saw cut and repair area is measured for

payment.

27.1.3 Compaction of SubbasePrior to placing the concrete in the removal area

and before installing dowels or tiebars, any subbase or

subgrade that is disturbed below the level of clean out

is removed. The repair area shall be compacted to the

satisfaction of the Engineer. Any area which has been

over excavated is to be filled with concrete. On

undercut full depth repairs, the removal of subbase for

the undercut is incidental and included in the pay item.


58


If undercut joints are specified, the Contractor

must be careful when removing subbase under thepavement which is to remain. Damage to the bottomof the slab that is to remain should not be tolerated. Ifa backhoe bucket plate is used, care must be exercisedor hand methods must be used to undercut theexisting slab.

27.1.4 Drilling Dowel or Tiebar HolesDrilling of holes for dowels or tiebars is to be

done with hydraulic or electric drills in a manner thatwill not spall or damage the existing concrete. Thesetypes of drills do not impact the face of the saw cutwith as much force as a pneumatic drill. Holes are tobe drilled with a device that allows independentadjustment of all drill shafts in the horizontal andvertical direction. The device shall be capable ofdrilling a minimum of three holes at one time. Holesare to be centered at midslab with a tolerance of plusor minus 13 mm (1/2 inch). Dowels or tiebars start300 mm (12 inches) from the outside edge ofpavement and are spaced at 305 mm (12-inch)spacing and stop 600 mm (24 inches) from theadjacent lane to avoid hitting existing tiebars at thelongitudinal joint. It is important that the Contractordrill holes parallel to the top of the pavement and bein proper alignment or smooth dowels when installedwill not perform properly.

Smooth dowels are to be epoxy coated and 38mm (1 1/2 inch) diameter by 460 mm (18 inches) inlength. Tiebars are to be #35M (No. 11) bars whichare 460 mm (18 inches) in length and epoxy coated.Holes for dowels or tiebars are to be 41 mm (1 5/8inches) in diameter and a minimum of 229 mm (9inches) deep into the concrete.

27.1.5 Grouting Dowels or TiebarsAll dowels and tiebars are to be grouted into place

with an epoxy, polyester or vinylester resin material.

The material is to be injected pneumatically into the

back of the hole and the dowel or tiebar inserted 230

mm (9 inches) into the hole. A nylon or plastic washer

is used to retain the grout in the hole by pushing it

flush against the saw cut after the bar is installed.

Sufficient grout is to be used to completely fill all

voids around the bar including any spalling at the face

of the sawcut. Other methods of installing dowels

shall not be permitted. Most Contractors doing this

work pump the resin and hardener from pressure pots

and the two materials are mixed immediately before

being extruded into the hole. In cooler temperatures,

it may be necessary to heat the grouting mateials so

the material flows easier and sets up in the required

30 minute time period. Dowels are to be held in

proper alignment until the grout has hardened.

27.1.6 Placing, Finishing and Curing

Placement of the concrete can begin when the

grout around dowels or tiebars has hardened and after

smooth dowels are coated with a thin layer of oil or

other bond breaking material. Rigid forms are

required at the outside edge of the full depth repair.

The concrete is placed in a continuous operation and

consolidated with internal vibration. Full depth

repairs 3.0 meters (10 feet) or greater in length are to

have tied longitudinal joints in accordance with

Standard Drawing BP 2.1M (BP 2.1). Steel paving

mesh is required in repairs greater than 3.0 meters (10

feet) in length or if the repair is to be opened within

24 hours of placement. The clearance from the end of

the mesh wires to the edge of the pavement or new

transverse joint is 100 mm ± 50 mm (4 ± 2 inches).

Specifications required that repairs less than 3.7

meters (12 feet) are to be screeded longitudinally

when striking off the top of the concrete. If the repair

is over 3.7 meters (12 feet), the screed shall be

perpendicular to the center line. After screeding and

floating is completed, the surface is to be tested with a

3.0 meter (10 foot) straightedge before the concrete

hardens to assure that the transition on and off the

repair meets a tolerance of 3 mm in 3.0 m (1/8 inch in

10 feet). Any high or low areas are to be corrected and the

surface rechecked to assure compliance.

Chapter 27.0: Concrete Pavement Repairs

59


The surface finish of the concrete repair shall

match the adjacent concrete. If the adjacent pavement

is smooth with a burlap drag, the patch should have

the same finish. If the patch texture is different, it may

be very noticeable when traveling over the patch at

normal traffic speed.

During finishing of the patch, the Contractor has

the option of forming the joint at the transverse saw

cuts. The forming can be done by use of a hand tool

with the proper joint width and depth as shown in the

standard, or an actual wood strip of the proper

dimensions can be used as a form. The Contractor is

also permitted to finish the concrete flush with the

adjacent pavement and diamond saw the joint after

the concrete has cured and before it is opened to

traffic.

After finishing and straightedge checking is

completed, the concrete is cured with white pigmented

curing membrane as per 451.10. This section requires a

uniform coverage of membrane at an application rate of

1 liter per 3.7 square meters (150 square feet per gallon).

27.1.7 Sealing of Transverse JointsTransverse joints are to be sealed with a hot

applied joint sealer meeting 705.04. Prior to sealing

the joint, both vertical faces of the joint are to be

cleaned by abrasive blasting to the depth of the

bottom of the sealer. The cleaning shall remove all

dirt, dust, tar or asphalt, curing compound

discoloration leaving a clean dry newly exposed

surface to seal. The hot applied sealer shall be 6 mm (1/4

inch) below the surface of the pavement. A bond breaking

tape is placed at the bottom of the joint curf immediately

before the hot applied material is placed.

27.1.8 Classes of ConcreteThe pay item description for Item 255 specifies

the class of concrete. The classes of concrete used for

this item will normally be Class C, S, FS or MS.

These classes of concrete are descibed in the Manual

of Procedures for Concrete.

27.1.9 Additional RequirementsFull depth repairs can be opened to traffic when

the flexural strength of 2.7 Mpa (400 psi) is attained.

Depending on the class of concrete used and the

atmospheric conditions, the time that this strength is

obtained will vary.

When traffic is adjacent to the lane being

repaired, the Contractor is to schedule his work so

that slab replacements 18.3 meters (60 feet) and less

in length are completed within 48 hours. Repairs 3.0

meters (10 feet) and less shall not be permitted to be

left open overnight. To protect the traveling public,

repairs 3.0 meters (10 feet) or less in length in which

the pavement has been removed but not filled at the

end of the day shall be covered with steel plates. The

Contractor shall plan his work so that no repairs are

left unfilled when work is suspended for holidays or

weekends. If the Contractor has removed pavement

and is unable to complete the repairs in the above time,

he shall fill the areas with a suitable temporary patch

material to the satisfaction of the Engineer.

27.2 Thin-Bonded Patching

The success of a thin-bonded patch is dependent upon

complete removal of all unsound or damaged

material, adequate bond between old and new

concrete, use of “no slump” air-entrained concrete

and proper curing. Strict adherence to all these

requisites is necessary for successful patching.

The limits of the damaged area first must be

determined and the area to be repaired established

beyond the affected area into sound concrete. A steel

rod or steel chain may be used to sound the surface to

determine hollow and unsound areas. The area

generally should be rectangular in shape and the

perimeter should be outlined by sawing to a depth of

approximately 25 mm (1 inch) to avoid feathered

edges which usually result in spalling. Additional saw

cuts within the outlined area will aid the breakup and


60


removal operation. Care should be exercised to

avoid sawing through the reinforcing since this is to be

a surface patch using the existing reinforcement. If the

steel is cut, the repair will have to be more extensive

since it will be necessary to install tiebars along the

vertical faces.

Removal may be accomplished by the use of air

hammers or other suitable equipment, to such depth

that includes all deteriorated material and exposes

sound concrete. Generally, it is desirable to remove all

concrete above the reinforcing so that the steel can be

inspected and corrected, if needed, and a patch of

substantial thickness will result. If the damage is the

result of insufficient cover over the reinforcing steel,

the concrete should be removed below the steel so that

it can be lowered before replacing the concrete. This

will result in obtaining the minimum cover and correct

the cause of deterioration.

The area should be cleaned of all loose material,

dirt, dust, etc., by flushing with water or blowing out

with compressed air. If water is used, it must be

mopped out thoroughly before abrasive blasting.

Abrasive blasting of the bonding surfaces must be

done after the area has dried.

A neat cement grout of non-air-entraining

cement and water having a consistency of a thick

paint should be brushed into the cleaned bonding

surface of the exposed concrete. Care should be

exercised to see that:

1. The surface is damp but free of surface water

when the grout is applied.

2. The grout is brushed into the surface to displace

all air films and to provide a uniform thickness

of 2 mm to 4 mm (1/16 to 1/8 inch).

3. The grout is not placed so far in advance that it

dries out before being covered with the patching

material.

The principal requirements of the concrete to be

used for patching are that it have only enough water

to make it cohesive and that it have sufficient air

entrainment. The use of “no slump” concrete is

necessary to avoid shrinkage upon drying and

hardening, thereby obtaining good bond with the

adjoining concrete. An adequate amount of entrained

air is vital if the concrete is to be durable. Therefore, a

minimum of 6 percent air content should be maintained

in the plastic concrete.

When feasible, concrete meeting the

specification requirements for pavement concrete

should be used. However, when this is impractical

due to a thin patch, it may be necessary to use small

coarse aggregate concrete or mortar only. When used,

these mixes shall have a minimum of 390 kg (658

pounds) of cement per cubic meter (cubic yard) and

an air content greater than 6 percent. It is desirable to

use high-early-strength cement in all concrete for

thin-bonded patching.

After the concrete is placed, it should be

consolidated thoroughly by use of a vibrating screed

or a vibrating plate, except where the patches are

extremely small, such as at spalls. Vibration is vital

for consolidating the “no slump” concrete. The

surface must be screeded to meet the adjoining

surfaces and immediately textured and cured.

Texturing is necessary to provide a skid resistant

surface and to blend with adjoining surface

appearance. With low slump concrete it is important

to apply membrane curing immediately after finishing

and texturing to prevent loss of moisture necessary for

strength. White-pigmented membrane is required.

The repaired area shall be protected from traffic

for a minimum of 8 hours. Where possible, protection

longer than the minimum is preferable. However,

when repairs are made on pavements and structures

subjected to traffic, it is desirable to remove

barricades as soon as possible. Planning the concrete

placement for early in the day and curing the

minimum of 8 hours will permit opening the same

day. The thin patch is supported by the underlying

existing concrete, gains strength quickly due to the

low water-cement ratio and should not be damaged by

traffic with this minimum curing.

Chapter 27.0: Concrete Pavement Repairs

61


Checklist for Inspection of Concrete Pavements

Subgrade1. Observe proof rolling or final rolling.

2. Remove and replace with suitable material any

unstable areas noted, and recheck.

3. Check for compliance with subgrade

tolerances.

Subbase1. Subbase with materials should be uniformly

spread.

2. Width of subbase placed should be at least 300

millimeters (12 inches) wider than the pavement

on both sides.

3. Material should have moisture content as

determined by the Engineer.

4. Observe compaction of subbase.

5. Make density determinations.

6. Correct unstable areas noted.

Forms1. Prepare grade for forms — should be a slight

removal of subbase material.

2. Forms should be clean and in good condition.

3. Set forms — should be uniformly supported —

no shimming.

4. Securely fasten form locks.

5. Drive form pins and securely lock them in pin

pockets.

6. Check alignment of forms — correct if

necessary.

7. Check forms for tolerance — 3 millimeters in

3.0 meters (1/8 inch in 10 feet) for top; 6 mm in

3.0 meters (1/4 inch in 10 feet) for vertical face.

8. Check width between forms. (See Plan line sheets.)

Fine Grade1. Sprinkle subbase prior to fine grading to

maintain desired moisture content.

2. Subgrader should be cutting rather than filling.

3. Observe operation of pin templet — correct

irregularities.

4. Subbase should be rerolled with light or medium

roller to restore surface density.

5. Make final density tests and thickness

determinations.

6. Remove excess subbase material along inside of

forms to full depth of forms.

7. The ideal time to observe the forms for deflection

or side movement is during the operation of the

sub-grader, since it is usually one of the heaviest

pieces of equipment operated on the forms. Any

deviations noted in the forms during its operation

should be corrected before placing concrete in the

area.

8. Recheck alignment and grade of forms.

Final Preparation for Concrete1. Install hook bolts where required — securely

fasten to forms at correct elevation. See

Standard Drawing BP-2.1M (BP-2.1).

2. Spray forms with light oil to prevent bond.

3. Install dowel assemblies. They should be

uniformly supported and securely staked using a

minimum of eight steel pins 13 mm diameter by

460 mm (1/2 in. diameter by 18 in.). When sand

subbase or material that may distort or settle is

62


used, six bearing plates approximately 125 mm (5

inches) square are required under each assembly.

See Standard Drawing BP-2.2M (BP-2.2).

4. Check alignment of dowels with adjustable A-

frame level or other suitable device. Dowels

should be parallel with the surface and with the

centerline of the pavement. (This is perhaps one

of the most critical phases of inspection since

the proper performance of the joint is dependent

upon the correct alignment of every dowel in the

joint assembly. One dowel out of alignment may

prevent the entire joint from functioning.)

5. At least one half (the free end) of every dowel

should be uniformly oiled to prevent bond.

Avoid excess application. See Standard Drawing

BP-2.2M (BP-2.2).

6. Position expansion caps on oiled ends of

expansion joint dowels.

7. Accurately mark location of all joint assemblies

for sawing joints.

8. Sprinkle subbase just prior to placing concrete

to prevent absorption of water from the

concrete.

9. Remove shipping wires from dowel basket

assemblies immediately prior to placing

concrete.

Placing Concrete1. Avoid access spillage of batches when charging

concrete spreader.

2. Check minimum mixing — 60 seconds for

central mixers —70 revolutions at mixing speed

for transit mixers.

3. Make entrained air, slump and yield

determinations and adjust to within specified

tolerances. Tests should be made immediately

after placing concrete within the forms. Never

incorporate into the work any concrete that

exceeds the maximum slump or contains less

than the minimum amount of entrained air.

(Entrained air and slump are both important for

obtaining durable concrete, but entrained air is

the most vital requirement for concrete to be

resistant to the effects of freezing and thawing

and its importance cannot be over emphasized.)

4. Concrete should be spread uniformly on the

subbase.

5. Spreader should be used to distribute concrete to

full width without voids.

6. Spreader should strike off concrete at proper

depth for positioning mesh within the specified

zone. See Standard Drawing BP-1.1M (BP-1.1).

7. Tiebars for longitudinal joints should be placed

at mid-depth of slab-check position periodically.

See Standard Drawing BP-2.1M (BP 2.1).

8. Concrete should be vibrated along the full length

of all expansion joint assemblies.

9. Prohibit workers from walking on assemblies

while vibrating or when placing mesh.

10. Paving mesh should be positioned within

specified clearance at forms and at joints. See

Standard Drawing BP-1.1M (BP-1.1).

11. A minimum overlap of 300 mm (12 inches) is

required when joining sections of mesh within a

slab transversely.

12. Laps are required to have four fasteners to hold

mesh pieces together. This requires a minimum

of four ties in a 3.6 meter (12-foot) width of

mesh.

13. Concrete should be placed, spread, and struck

off for the top course.

14. If vibrators are mounted on a spreader, they

should be shut off when spreader stops.

15. If mesh is placed by vibratory method,

periodically check depth and clearance at

transverse joints. Revert to two-course method

at expansion joints and when abutting an

approach slab or existing pavement.

16. Movement of the mesh in the direction of paving

has been noted, especially when the vibratory

63



method of mesh placement is used. It is

important that periodic checks be made to assure

that the clearance is maintained at all transverse

joints.

Finishing1. Machine finishing should be delayed as long as

it is practical to permit consolidation of the

concrete.

2. A roll of concrete should be maintained ahead of

all screeds at all times. The roll should be at

least 100 mm (4 inches) but not more than 250

mm (10 inches) and should be uniform.

3. First screed should be tilted slightly to provide

compaction and surge.

4. The entire surface should be straightedged using

straightedges at least 3.0 meters (10 feet) in

length.

5. If floats of any types are used, they should

precede the straightedging or the surface should

be rechecked with the straightedge.

6. Caps protecting preformed expansion joint

material should be removed as concrete sets and

the joint should then be hand finished.

7. Prohibit the use of water on the surface of the

concrete to aid in finishing. (This practice results

in an increase in the water-cement ratio and a loss

of entrained air of the surface concrete, thereby

decreasing its durability. Surface scaling can

usually be traced to these areas.)

8. Edges along forms should be finished using an

edging tool.

9. Immediately prior to tine texturing transversly, a

turf drag or broom drag finish shall be provided.

The surface shall be a uniform gritty texture in

the longitudinal direction.

10. Periodic checks should be made to assure

specified texture is being obtained. Texturing

equipment should be raised from the surface

when not in use. The transverse texture should

be a relatively uniform pattern of grooves

spaced at 16 mm (5/8 inch) centers and grooves

shall be 4 mm (0.15 inches) deep and 3 mm

(0.10 inches) wide.

11. Areas above and at ends of expansion joint

material should be free of concrete.

Curing1. Just prior to applying curing membranes, station

numbers should be stenciled into the concrete.

Use “+000” (“+ 00”) stencils for Station 0 + 000

to 9 + 000 (0 + 00 to 9 + 00) only.

2. Curing membrane should be applied after the

water sheen has disappeared from the surface of

the concrete.

3. Membrane should be thoroughly agitated prior

to use.

4. Daily checks should be made to assure minimum

coverage of 1 liter per 3.7 square meters (1

gallon per 150 square feet) for 451, 452 and 453

pavement and 1 liter per 4.9 square meters (1

gallon per 200 square feet) for 305 base.

5. After removal of forms, membrane should be

applied to the pavement edges. Any surface

membrane which has been broken or damaged

should be touched up at this time.

Joints1. Standby saw in operating condition should be

maintained on project during sawing operations.

2. Center of transverse joints should be established

from previously placed marks.

3. Sawing of transverse joints should be done

before the concrete cracks but without excessive

raveling. The timing of the sawing is critical and

varies with temperatures and materials used.

Close attention is necessary to avoid random

cracking.

4. If random cracking occurs while sawing a

transverse joint, immediately cease sawing at


64


that joint and move ahead three to five joints.

Resume sawing the joints at that interval until

caught up with rate of hardening. The intervening

joints may then be sawed without random

cracking.

5. Timing of longitudinal joint sawing is not as

critical; however, they should be sawed within

three days.

6. Saw cuts should be straight and perpendicular to

the surface of the pavement.

7. Saw cuts should be cleaned immediately after

sawing by a jet of water under pressure. If

sawing is being done dry, compressed air may

be used in lieu of water.

8. Depth and width of saw cut should be checked

periodically. Transverse joints and longitudinal

joints shall have minimum depth of 1/4 of the

slab thickness for pavement less than or equal to

255 mm (10 inches) and 1/3 of the slab

thickness if the pavement is greater than 255

mm (10 inches). The width of the saw cut shall

be 6 ± 1.6 mm (1/4 ± 1/16 inch) determined at

the time of sawing.

9. Joint openings should be filled as soon as

practical.

Sealing1. All joints should be sealed prior to opening to

traffic or to use by construction equipment.

2. Joints should be cleaned just prior to sealing by

operating a saw blade backwards through the

joint.

3. Joints should be further cleaned by means of a

water jet or compressed air and should be clean

and dry when sealer is placed.

4. Joints should be filled flush when liquid fillers

are used. Preformed sealers should be

approximately 6 mm (1/4 inch) below the

surface.

5. All underfilled joints should be resealed and all

excess and unsightly sealer should be removed

before final acceptance.

EquipmentWhile it is not the duty nor the right of the

Inspector to adjust the Contractor’s equipment, he

should satisfy himself that all the necessary

equipment is on the job, placed on the forms, and

adjusted. The Inspector should observe the

Contractor’s personnel making the checks, and

adjustment if needed, for all screeds and pan floats

prior to placing concrete.

All equipment should be synchronized so that

each machine leaves the concrete in the proper

condition for the machines that follow. The last

machine may not be doing its job properly due to

improper adjustment of the previous one.

An approved spreader is required when the

width of pavement being placed in one operation is

3.6 meters (12 feet) or greater and the total square

meters (square yardage) of any given width exceeds

8,300 (10,000).

A self-propelled concrete finishing machine is

required for compacting and finishing the concrete. If

the finisher has two screeds, they shall be

independent-ly operated. If the finisher has only one

screed, the screed shall be not less than 460 mm (18

inches) in width and shall have compensating springs to

minimize the effect of momentum of the screed on the

side forms.

Central mixers and transit mixers may not

exceed the manufacturer’s rated capacity. Minimum

mixing shall be 60 seconds for central mixers and 70

revolutions at mixing speed for transit mixers.


65

Item 453 - Continuously ReinforcedConcrete Pavement

Pay Unit - Square Meter (Square Yard) -

Continuously Reinforced Concrete Pavement

Item 611 - Approach SlabsPay Unit - Square Meter (Square Yard) -

Reinforced Concrete Approach Slabs

Documentation Forms for Items 305, 451, 452,

453 and 611:

D-1 C-119 Inspector’s Daily Report

D-2 Reverse Side of C-119, calculations,

sketches, etc.

D-3 C-145 Rigid Pavement Daily Report

D-4 TE-45 Concrete Inspector’s Daily

Report

D-5 Reverse Side of TE-45 Report

Method of measurement for Items 305, 451, 452,

453 and 611:

Square meters (square yards) calculated from

verified plan dimensions.

Documentation Procedures

It is the intent of this section to recommend minimum

documentation requirements by combining and/or

eliminating various inspection forms now in use and

still document information in sufficient detail to

verify that construction is in substantial conformity

with the proposal, plans and specifications.

See D-1 thru D-6 for samples of forms discussed in

this section.

Item 305 - Portland CementConcrete Base

Pay Unit - Square Meter (Square Yard) - Portland

Cement Concrete Base

Item 451 - Reinforced Portland CementConcrete Pavement

Pay Unit - Square Meter (Square Yard) -

Reinforced Portland Cement Concrete Pavement

Item 452 - Plain Portland CementConcrete Pavement

Pay Unit - Square Meter (Square Yard) - Plain

Portland Cement Concrete Pavement

66 STATE OF OHIO DEPARTMENT OF TRANSPORTATION

APPENDIX D-1. C119 INSPECTORS DAILY REPORT

(front side)67

APPENDIX D-2. C119 INSPECTORS DAILY REPORT

(reverse side)68

APPENDIX D-3. E-145 RIGID PAVEMENT DAILY REPORT 69

APPENDIX D-4. TE-45 CONCRETE INSPECTORS DAILY REPORT

(front sheet)70

APPENDIX D-5. TE-45 CONCRETE INSPECTORS DAILY REPORT

(reverse side) 71


Glossary of Words or Terms as Applied to the Rigid Pavement Section ofthe Manual of Construction Procedures

Admixture - A substance other than cement, water

or aggregate added to a batch of fresh concrete to

alter one of the normal properties of concrete.

Aggregate - Mineral material, such as sand, gravel,

crushed stone, slag, or the combination thereof,

with which cement is mixed to form a mortar or

concrete. “Fine aggregate” may be considered as

the material that will pass a 4.75 mm (No. 4)

screen, and “coarse aggregate” as the material that

is retained thereon.

Batch - The combination of amounts of cement,

aggregate, water and admixture which will be

mixed at one time in a mixer.

Batching Plant - The plant either on or off the work

site where the materials are assembled by batches

for the mixer. Water and admixtures usually are

added as the batch is introduced into the mixer.

Beam, Test - A beam of specified size molded on

the job and later broken in a testing machine to

determine the flexural strength of the concrete.

Bleeding - Flow of water to the surface of freshly

placed concrete.

Cap - A short tube, closed at one end, placed on the

oiled end of a dowel in an expansion joint to

provide space for movement of the dowel in

hardened concrete. A stop in the tube prevents it

from being pushed all the way onto the dowel

before the concrete hardens.

Cement - A mixture of clay, limestone and other

selected materials heated to high temperature and

ground into powder. Mixed with water it forms a

paste to surround and bind the aggregate into a solid

and durable mass.

Change Order - A written order issued by the

Director to the Contractor, covering changes in the

plans or quantities or both, within or beyond the

scope of the contract and establishing the basis of

payment and time adjustments for the work affected

by the changes.

Contraction Joint - A joint which controls the

location of a transverse crack and permits the slab to

contract and expand with changes in temperature.

Contractor - The individual, firm or corporation

contracting with the Ohio Department of

Transportation for the performance of prescribed

work, acting directly or through a duly authorized

representative and qualified under provisions of the

law.

Construction Joint - A joint formed in concrete

pavement at the end of the day’s production or any

time production is interrupted for 30 minutes or

longer.

Core - A cylinder of concrete cut from pavement

with a hollow drill. Cores are 200 mm (4 inches) in

diameter and are used to check the thickness and

strength of the concrete.

Course - The depth of concrete pavement obtained

in one pour.

Crown - The height of the center of the roadway

surface above a straight line drawn between its

edges.

Cure - The treatment given concrete to assure

sufficient water and heat necessary for chemical

action so that concrete attains the strength and

durability for which it was designed.

72


Curing Membrane - A compound sprayed over the

exposed surface and edges of newly placed

concrete to prevent the evaporation of water during

curing.

Cylinder - A test sample of concrete molded into a

cylinder 600 mm (12 inches) high and 300 mm (6

inches) in diameter, to be sent to the Laboratory for

determination of strength and density.

Deformed Bar - A steel bar which has projections

on its surface for increasing the bond between the

concrete and the bar.

Density (Soil) - The density of soil is its weight-

volume relationship, which usually is expressed in

kilgrams of soil per cubic meter (pounds of soil per

cubic foot).

Department - The Ohio Department of Transportation.

Director - The Director of Transportation, the

Assistant Director of Transportation, the Deputy

Director of the Division of Highways, the Deputy

Director of the Division of Urban Mass

Transportation, the Deputy Director of the Division

of Aviation, the Chief Engineer of the Division of

Highways, the Highway Construction

Administrator, the Operation and Maintenance

Administrator, the Highway Design Administrator,

the Engineer of Construction, the Engineer of

Maintenance, the Engineer of Bridges, or the

Engineer of Tests.

Documentation - Recording and filing evidence

that the material or work is in conformance with

specifications in the amounts determined.

Dowel or Dowel Ba r - A smooth steel bar

extending across a concrete joint to transfer the

applied load, prevent future misalignment of the

slab and permit movement at the joint.

Dowel Assembly - A cage or basket used to hold

dowels in position during placement of concrete.

Edging - Rounding the edges of concrete pavement

and hand-formed joints while the concrete still is

workable, using an edging tool of specified radius.

Elevation or Grade - The height as measured

from a predetermined point denoted in the

plans.

Engineer - The District Deputy Director of

Transportation, the District Construction Engineer,

the District Operations Engineer, the District

Testing Engineer or the Project Engineer assigned

to administer the contract.

Expansion Joint - A joint adjacent to a bridge or

intersection to absorb expansion of concrete

pavement and prevent expansive pressure on the

bridge or intersecting pavement.

FHWA - Federal Highway Administration, U.S.

Department of Transportation.

Fine Grading - Removing approximately 25 mm (1

inch) of the primary subbase and rerolling to bring

to exact grade, upon which the concrete pavement

is placed.

Finishing - Shaping the surface of concrete that is

not shaped by forms. Also it includes filling visible

voids in the concrete after the forms are removed.

Finishing Machine - A machine which screeds and a

float for performing the final grade and smoothness

of the concrete pavement to meet the requirements.

Float - A straight piece of wood or metal used to

smooth the surface of plastic concrete. Small hand-

held floats are called paddle floats.

Forms, Pavement - Metal plates secured together

and to the subbase for shaping the sides of the

pavement and controlling alignment, grade and

thickness. Also, the forms serve as a track for

paving equipment.

Grade (noun) - See Elevation.

Grade (verb) - To add or remove earth to obtain a

desired level or slope.

Hand Finishing - Correcting manually irregularities

left by the finishing machine or performing those

functions which cannot be accomplished by machine,

such as edging or forming of joints.

73

Glossary


Head - The roll of plastic concrete which forms

ahead of a screed plate.

Honeycombing - Large voids in the concrete which

are due to inadequate spading or consolidating.

Hook Bolt - A short steel bar with hooked ends

joined by a threaded connection. Use is to fasten a

concrete slab to another later constructed beside it.

Inspection - Examination by observation,

measurement, or tests to determine that materials

and work are in conformance with specifications.

Joint Lock - The device at each end of a section of

paving form for attaching the sections together.

Job Control - Steps taken to keep quality and

quantity of materials and work on a project within

the specifications and plans.

Joint Sealer - A compound for preventing entrance

of water and solid particles into a joint. The sealer

may either be preformed or liquid.

Laboratory (Laboratory with “L” capitalized) -

Testing Laboratory of the Department of

Transportation, 1600 West Broad Street,

Columbus, Ohio 43223. If reference is to the

District laboratory, it is so designated.

Laitance - An accumulation of fine particles on the

surface of freshly placed concrete occurring when

there is an upward movement of water through the

concrete due to the presence of too much mixing

water or excessive vibration.

Lane or Traffic Lane - A strip of pavement of

specified width, usually 3.6 meters (12 feet).

Longitudinal Joint - A joint which extends

lengthwise in the roadway, parallel to the

centerline.

Mesh - A fabric of steel wires welded together at

their intersections for placement in concrete

pavement as distributed reinforcement.

Mesh Installer - A machine for imbedding wire

mesh into freshly placed concrete pavement.

Mortar - A mixture of water, sand and cement.

Mixed with coarse aggregate, this mortar

completely envelopes each particle of coarse

aggregate to form concrete. Also, mortar is used to

fill honeycombing which becomes apparent upon

removal of forms.

Oscillating - To swing back and forth, operating

between fixed limits, such as the movement of a

screed on a finishing machine.

Pin Template or Templet - A device used to check

the surface of the subbase.

Plans - The plans, profiles, typical cross sections,

working drawings and supplemental drawings,

approved by the Director, or exact reproductions

thereof, which show the location, character,

dimensions, and details of the work.

Project - The specific section of the highway

together with all appurtenances and construction to

be performed thereon under the contract.

Project Engineer - The person representing the

Department who is charged with the overall

responsibility at the project site for seeing that

construction is in conformance with plans and

specifications, and that all checks for job control

and validation of pay items are documented and

filed properly.

Proposal - The offer of a bidder, on the prescribed

form properly signed and guaranteed, to perform

the work and to furnish the labor and materials at

the prices quoted.

Raveling - Slightly disturbing the surface of

concrete pavement adjacent to sawing of a joint.

Random Cracks - Cracks which appear in concrete

pavement due to contraction in the early stages of

curing, and which follow no set pattern.

Rigid Pavement Inspector - An authorized

representative of the Engineer to make detailed

inspections and documentation of contract

performance as pertain directly to concrete paving

operations.


74


Sawing - Using a circular saw to cut a groove in the

surface of the pavement to control the location of

transverse cracks.

Scaling - Peeling away of small amounts of the

concrete surface.

Screed - A long metal plate moved across the

surface of freshly placed concrete with a sawing

motion to consolidate the concrete and rough finish

it approximately to grade.

Segregation - The unintentional separation of the

larger pieces of aggregate from the smaller pieces

within one size of aggregate or within a mixture of

sizes of fresh concrete.

Shim - A thin piece of stone, wood or other material

used to raise the object resting on it to the desired

elevation. (Not permitted in adjusting forms to

grade.)

Slab - A continuous portion of concrete paving

bounded by joints and/or the edge of the pavement.

Slip Form Paving - Concrete paving by use of a

machine carrying its own forms between which

low slump concrete is compacted sufficiently to

retain its shape after the machine has progressed

onward.

Slump - Measured in millimeters (inches) on a

vertical axis, the amount that a sample of fresh

poured concrete that has filled a standard inverted

cone will sink down after the cone has been

removed. A measure of the consistency and

workability of concrete.

Spading -Repeatedly inserting a flat steel blade

edgewise into fresh poured concrete for

consolidation and to drive out entrapped air,

particularly where the concrete meets the forms or

imbedded objects.

Spalling - The breaking away of hardened parts of

concrete from the main body at surface points.

Specifications - The directions, provisions and

requirements contained in the State of Ohio,

Department of Transportation Construction and

Material Specifications as supplemented by the

supplemental specifications and special provisions.

Spreader - A machine which distributes fresh

concrete generally over the area between the

forms.

Standard Drawings - The Standard Construction

Drawings issued by the Bureaus of Location and

Design, Bridges and Design Services.

Station Marker - A numeral impressed into the

surface of newly finished concrete pavement and

located at specified longitudinal intervals near the

edge of the roadway for purposes of future location

references.

Straightedging - Placing a 3.0 meter (10 foot)

straightedge on the finished pavement surface to

determine if the surface is within tolerance.

Strike Off - Using a straightedge to scrape off excess

concrete which may protrude above the mold or

forms.

Subbase - The layer of specified, compacted

material placed on the prepared subgrade to serve

as a base for pavement.

Subgrade - The portion of a roadbed upon which

the pavement structure and shoulders are

constructed after it is prepared.

Surge - The rise in the surface of plastic concrete

following the release of compaction after the

screed has passed over it.

Texturing - Slight roughening of the finished

surface of concrete pavement to provide greater

safety through increased traction to the tires of

vehicles which will pass over it.

Thin-Bonded Patching - Repairing concrete

pavement only to the depth of unsound concrete

rather than the full depth of the pavement.

Tie Bar - A deformed dowel or hook-bolt placed

across longitudinal joints of concrete pavement

near middle depth to tie the slabs together and hold

the joint closed.

Tieing - Wiring together overlapped mesh that is

hand-tied by use of rings similar to hog rings.

Tolerance - The permitted variation from a specified

condition.

Glossary

75


Traction Speed - The rate of forward movementparallel to the centerline by the paving equipment.

Transverse - A theoretical line runningperpendicular to the longitudinal or centerline of aroadway.

Validation - The signature or initials of anauthorized individual on any form or ticketdenoting that the information is as stated.

Verification - The steps necessary to determine thatthe work or materials described are in conformancewith plans and specifications.

Vibrator - A device for pulsating fresh concrete sothat entrapped air is released, and the concretesettles uniformly about reinforcement and to the

forms.

Wearing Plate - A small plate which drags over the

top of the pavement forms or adjacent paving to

control the height of the screed plate.

Windrow - An accumulation of material as a result

of rolling up or sliding off to the side. Applies here

to loose material just inside of the forms left by the

subgrader in the fine grading operation.

Yield - A check on the mix design made by dividing

the total batch weight by the determined weight per

unit volume. The actual volume thus obtained is

compared to the design volume.

76



Index

Batch Plants, Storing of Aggregate .................................................................................................... 9

Scales ..................................................................................................................................................... 9

Site Preparation ...................................................................................................................................... 9

Stock Piling ............................................................................................................................................ 9

Check List for Inspection of Concrete Pavements .................................................................... 62

Cold Weather Construction .................................................................................................................... 51

Combination Float Finisher Operation ................................................................................................ 32

Adjust to Proper Speed ............................................................................................................................ 32

Metering Concrete to Machine ................................................................................................................ 32

Setting Screeds and Float ......................................................................................................................... 32

Concrete—Moisture and Mix Control ................................................................................................... 26

Concrete Pavement Repairs ................................................................................................................... 57

Full Depth Pavement Replacement.......................................................................................................... 57

Thin-Bonded Patching ............................................................................................................................. 61

Concrete Placing and Spreading ........................................................................................................... 27

Placing on Grade ...................................................................................................................................... 27

Spreading ................................................................................................................................................. 27

Care at Joints ............................................................................................................................................ 27

Head ......................................................................................................................................................... 27

When Required ........................................................................................................................................ 27

Vibration .................................................................................................................................................. 28

Curing ........................................................................................................................................................... 43

Effect of Variable Weather ...................................................................................................................... 43

Membrane Curing .................................................................................................................................... 44

Sheeting.................................................................................................................................................... 45

Types Permitted ....................................................................................................................................... 43

77


Value of Adequate Cure........................................................................................................................... 43

Water Curing ............................................................................................................................................ 45

Documentation Procedures .................................................................................................................... 67

Documentation Forms.............................................................................................................................. 69

Edge Patching ............................................................................................................................................ 46

Cleaning at Joints ..................................................................................................................................... 47

Curing Edges ............................................................................................................................................ 47

Repairing Honeycomb ............................................................................................................................. 46

Field Checking ............................................................................................................................................ 37

Crown ....................................................................................................................................................... 38

Pavement Thickness ................................................................................................................................ 38

Recording Checks .................................................................................................................................... 39

Running Yield .......................................................................................................................................... 37

Final Finishing ............................................................................................................................................ 40

Edging ...................................................................................................................................................... 41

Station Numbers ...................................................................................................................................... 42

Straight Edging ........................................................................................................................................ 40

Texturing .................................................................................................................................................. 41

Form Removal ............................................................................................................................................ 46

Forms ............................................................................................................................................................ 13

Checking .................................................................................................................................................. 13

Keys and Locks ........................................................................................................................................ 13

Oiling ....................................................................................................................................................... 14

Setting ...................................................................................................................................................... 13

Glossary ....................................................................................................................................................... 71

Hot Weather Construction ....................................................................................................................... 49

Inspection Personnel Assignment ........................................................................................................ 3

Joints ............................................................................................................................................................ 15

Construction Joints .................................................................................................................................. 18

Dowels ..................................................................................................................................................... 16

78



Sawing...................................................................................................................................................... 20

Construction Joints .................................................................................................................................. 23

Checking Assemblies ............................................................................................................................... 17

Dowels ..................................................................................................................................................... 16

Placing Assemblies .................................................................................................................................. 16

Preventing Bond....................................................................................................................................... 17

Sawing...................................................................................................................................................... 20

Ties ........................................................................................................................................................... 17

Expansion Joints ...................................................................................................................................... 18

Caps.......................................................................................................................................................... 18

Expansion Material .................................................................................................................................. 18

Sawing...................................................................................................................................................... 20

Longitudinal Joints .................................................................................................................................. 15

Placing...................................................................................................................................................... 15

Sawing...................................................................................................................................................... 20

Ties ........................................................................................................................................................... 15

Sealing...................................................................................................................................................... 47

Sawing and Forming ................................................................................................................................ 20

Checking .................................................................................................................................................. 23

Measurement .............................................................................................................................................. 56

Mechanical Equipment ............................................................................................................................. 5

Combination Float Finisher ..................................................................................................................... 7

Mesh Installers ......................................................................................................................................... 6

Site Mixers ............................................................................................................................................... 7

Slip Form Pavers ...................................................................................................................................... 8

Spreaders .................................................................................................................................................. 5

Transit Mix and Central Mix Equipment ................................................................................................. 7

Transverse Finishing Machines ............................................................................................................... 6

Vibrators .................................................................................................................................................. 5

Pavement Cores ......................................................................................................................................... 54

Pavement Inspection ................................................................................................................................ 3

Pavement Repairs ..................................................................................................................................... 57

Full Depth Pavement Replacement.......................................................................................................... 57

Thin Bonded Patching.............................................................................................................................. 60

79

Index


Reinforcement ............................................................................................................................................ 24

Condition of Mesh ................................................................................................................................... 24

Handling ................................................................................................................................................... 24

Placing...................................................................................................................................................... 24

Tieing ....................................................................................................................................................... 25

Slip Form Paving ....................................................................................................................................... 34

Grade Control ........................................................................................................................................... 35

Finishing .................................................................................................................................................. 35

Placing Concrete ...................................................................................................................................... 34

Subbase .................................................................................................................................................... 34

Specifications ............................................................................................................................................. 3

Subbase ........................................................................................................................................................ 11

Fine Grading ............................................................................................................................................ 11

Moisture Control ...................................................................................................................................... 12

Pin Template ............................................................................................................................................ 12

Placing...................................................................................................................................................... 11

Rechecking Forms ................................................................................................................................... 12

Recording Checks .................................................................................................................................... 12

Subgrade ...................................................................................................................................................... 10

Preparation ............................................................................................................................................... 10

Proof Rolling ............................................................................................................................................ 10

Requirements ........................................................................................................................................... 10

Tolerance Check ...................................................................................................................................... 10

Surface Smoothness ................................................................................................................................ 55

Testing and Sampling ...............................................................................................................................52

Transverse Finishing Machine Operation ........................................................................................... 29

Care at Expansion Joints .......................................................................................................................... 31

Effect of Mix Consistency ....................................................................................................................... 30

Factors Involved....................................................................................................................................... 29

Clean Rails ............................................................................................................................................... 29

Head—Screed .......................................................................................................................................... 29

Height and Tilt ......................................................................................................................................... 29

Surge ........................................................................................................................................................ 30

Traction Speed and Stroke ....................................................................................................................... 29


80


General Operation ..................................................................................................................................... 30

Passes Necessary ..................................................................................................................................... 30

Relation—Traction to Stroke .................................................................................................................. 31

Results to be Obtained ............................................................................................................................. 29

Work to be Performed .............................................................................................................................. 29

Index

81

Rigid Pavement - Ohio Department of Transportation

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