Specs

2004

Presented By:

NEMESIO C. CAEGBureau of Research & Standards

ITEM DESCRIPTION

This item consist of: pavement of Portland cement concrete, with or without reinforcement constructed on the prepared base in accordance with specification in conformity with lines and grades, thickness and typical cross-section of the plans.

MATERIALS REQUIREMENTS

1. Portland Cement• Only Type I Portland Cement shall be used unless otherwise

provided for in the Special Provisions.

• Different brands or the same brands from different mills shall not be mixed nor shall they be used alternately unless the mix is approved by the Engineer.

• The use of Portland Pozzolan Cement Type IP meeting the the requirements of AASHTO M240/ASTM C 695 shall be allowed, provided that the trial mixes shall be done and that the mixes meet the concrete strength requirements.

• Cement that has become partially set or which contains lumps of caked cement will be rejected. Likewise, cement salvaged from discarded or used bags shall not be used.

1. Portland Cement

• The product of only one mill of any one brand and type of Portland Cement shall be used on the project unless otherwise permitted by the Engineer.

• The Contractor shall provide suitable means of storing and protecting the cement against dampness.

2. Fine Aggregate

• consists of natural sand, stone screenings, or other inert materials with similar characteristics, or combinations thereof, having hard, strong and durable particles.

• material passing the 0.075 mm ( No. 200 sieve ) shall not contain more than (3) mass percent by washing nor more than (1) mass percent each of clay lumps or shale.

• when subjected to five (5) cycles of the sodium sulfate soundness test, the weighted loss, shall not exceed 10 mass percent

• if subjected to the calorimetric test for organic impurities and a color darker than the standard is produced, it shall be rejected.

• shall be free from injurious amounts of organic impurities.

• when tested for the effect of organic impurities of strength of mortar, the fine aggregate may be used if the relative strength at 7 and 28 days is not less than 95 mass percent

2. Fine Aggregate

Grading Requirements for Fine Aggregates

Sieve Designation Mass Percent Passing 9.5 mm ( 3/8 in. ) 100

4.75 mm ( No. 4 ) 95 - 100 2.36 mm ( No. 8 ) -

1.18 mm ( No. 16 ) 45 - 80

0.600 mm ( No. 30 ) - 0.300 mm ( No. 50 ) 5 - 30

0.150 mm ( No. 100 ) 0 - 10

3. Coarse Aggregate

• consists of crushed stone, gravel, blast furnace slag, or other approved inert materials of similar characteristics, or combinations thereof, having hard, strong, durable pieces and free from any adherent coatings.

• contain not more than one (1) mass percent of material passing the 0.074 mm ( No. 200 sieve ) by washing nor more than 0.25 mass percent of clay lumps, nor more than 3.5 mass percent of soft fragments.

• if subjected to five (5) cycles of the sodium sulfate soundness test, the weighted loss shall not exceed 12 mass percent.

• shall have a mass percent of wear not exceeding 40 when tested to Los Abrasion machine.

Grading Requirement For Coarse Aggregate

Sieve Designation Mass Percent Passing

Standard Alternate Grading Grading Grading mm U.S. Std. A B C 75 3 in. 100 - - 63 2 – ½ in. 90 – 100 100 100 50 2 in. - 90 – 100 95 - 100

37. 5 1 – ½ in. 25 – 60 35 – 70 - 25 1 in. - 0 – 15 35 – 70 19 ¾ in. 0 – 10 - -

12.5 ½ in. 0 – 5 0 – 5 10 – 30

4.75 No. 4 - - 0 – 5

4. Water

• water will be tested in accordance with and shall meet the requirements of Item 714, Water.

• water which is drinkable and known of potable quality may be used without test.

• where the source is shallow, the intake shall be so enclosed as to exclude silt, mud, grass or other foreign materials.

• when used in mixing , curing or other designated application it shall be reasonably clean and free of oil, salt, acid, alkali, grass or other substances injurious to the finished product.

5. Reinforcing Steel

• tie bars shall be deformed bars that are to bent and re-straightened during construction and shall conform to the requirements of AASTHO M 31 or M 42.

• dowel bars shall be plain round bars where one-half of the length shall be painted with one coat of approved lead or tar paint and shall conform to the requirements of AASTHO M 31 or M42.

• reinforcing steel shall be free from dirt, oil, paint, grease, mill scale and loose or thick rust which could impair bond of the steel with the concrete.

6. Joint Fillers

• poured joint fillers shall be mixed asphalt or rubber filler conforming to the requirements of AASTHO M 173.

• preformed fillers for joints shall conform to the requirements of AASTHO M 33 ( ASTM D 994 ), AASTHO M 153, AASTHO M 213, AASTHO M 220, as specified in the plans and shall be furnished in a single piece for the depth and width required for the joint.

7. Admixtures

• admixtures should be added only to the concrete mix to produce some desired modifications to the properties of concrete where necessary, but not as partial replacement of cement. • air-entraining admixture shall conform to the requirements of AASTHO M 154.

• chemical admixtures, if specified or permitted, shall conform to the requirements of AASTHO M 194. • fly ash, if specified or permitted as a mineral admixture and as 20 % partial replacement of Portland Cement in concrete mix shall conformed to the requirements of ASTM C 618.

Reasons for Using Admixtures in Concrete

to reduce the cost of concrete construction,

to achieve certain properties in concrete more effectively than by other means,

to ensure the quality of concrete during the stages of mixing, transporting, placing, and curing in adverse weather conditions,

to overcome certain emergencies during concreting operations.

Classification of Admixtures According to Function

1. Air – entraining admixtures2. Water – reducing admixtures

3. Retarding admixtures

4. Accelerating admixtures

5. Super - plasticizers

6. Finely divided mineral admixtures

7. Miscellaneous admixtures such as workability, bonding, damp proofing, permeability-reducing, grouting, gas forming coloring, corrosion inhibiting and pumping admixtures.

8. Curing Materials

• curing materials shall conform to the following requirements as specified:

a. Burlap cloth - AASTHO M 182

b. Liquid membrane forming compound - AASTHO M 148

c. Sheeting ( film ) materials - AASTHO M 171

Storage of Materials

Cement• cement shall be stored immediately upon delivery at the site in a weatherproof building which will protect the cement from dampness.The floor shall be raised from the ground.• bulk cement, if used, shall be transferred to elevated air tight weathered proof bins.

• cement bags shall be stacked closed together to reduce air circulation but should never be stacked against outside walls.

• stack the cement bags so that the first in are the first out

• on small jobs where a shed is not available, bags should be placed on raised wooden platforms at least 4 to 6 inches above the ground and water coverings should fit over the pile and extend over the cement and the platform.

Concrete Aggregates

• to secure greater uniformity of concrete mix, different sizes of aggregates shall be stored in separate bins or separate stockpiles to prevent the material at the edges of the piles from becoming intermixed.

Reinforcing Steel• steel bars shall be stored immediately upon delivery at the site in a weatherproof location which will protect the steel bars from corrosion. The floor shall be raised from the ground.

PROPORTIONING, CONSISTENCY AND STRENGTH OF CONCRETE

Minimum Cement Factor:

- to meet the minimum strength requirements for paving concrete, it is required to have at least 364 kg. of cement per cubic meter of concrete or a cement content of 9.1 bags/cu.m. of concrete on a 40 kg. per bag of cement

Slump Requirements :

- if vibrated, a slump between 37.5 – 75 mm (1-1/2 – 3 inches)

- if not vibrated, a slump between 12.5 – 37.5 mm (½ - 3 inches)

Strength Requirements :

- flexural strength @ 14 days of 3.8 MPa (550 psi), when tested by the third point method or 4.5 MPa (650 psi), when tested by mid-point method

- compressive strength @ 14 days of 24.1 MPa (3500 psi) for cores taken and tested in accordance with AASTHO T 24

PROPORTIONING, CONSISTENCY AND STRENGTH OF CONCRETE

CONSTRUCTION REQUIREMENTS

Preparation of Grade

• the prepared base shall be checked of the required density, surface imperfections and finished grade elevation.

• the prepared base shall be extended and compacted at least 60 cm. beyond the edge of the proposed concrete pavement to ensure that the density of the base at the edge of pavement is the same as on its carriageway that can support the paving machine when it is used.

• the prepared base shall be uniformly moist prior to the placing of concrete especially during hot/dry weather to keep the dry base from absorbing too much water from the concrete mixture, thus decreasing the amount of evaporation from the concrete surface.

Setting of Forms

• any roadbed, which at the form line is found below established grade, shall be filled with approved granular materials to grade in lifts of 3 cm. or less, and thoroughly re-rolled or tamped.

• the forms after setting to the correct grade, it shall not deviate from the true line by more than one (1) cm at any point.

• forms shall be of steel and of equal depth equal to the thickness of the pavement at the edge and provided with adequate devices for secure setting.

Placing of Concrete

• concrete shall be unloaded into an approved spreading device and shall be deposited continuously as near as possible to its final position to prevent segregation of the materials.

• placing shall be continuous between transverse joints and the use of hand spreading shall be done with shovels not rakes. Workmen shall not be allowed to walk in a freshly mixed concrete with boots or shoes coated with earth or foreign substances. • when concrete is to be placed adjoining a previously paved lane and a mechanical equipment will be operated upon the newly paved lane, such equipment will be allowed to carry on that previously constructed lane provided it has attained the strength for 14 day concrete.

Conditioning of Prepared Base Course

• the prepared base material shall be brought to proper cross-section.

• high areas shall be trimmed to proper elevation

• low areas shall be filled and compacted to a condition similar to that of the surrounding grade.

• the finished grade shall be maintained in a smooth and compacted condition until the pavement is placed.

Mixing of Concrete

• the concrete may be mixed at the site of the work, in a central-mix plant, or in truck mixers• concrete mix when supplied by a batching plant, shall only be allowed in the DPWH projects provided it is duly accredited by the BRS ( DO # 253, S. of 2003 ).

• batching plants installed/used in the DPWH contract projects shall also be required to be accredited prior to supply the concrete mix.

• concrete when mixed at the site or in a central mixing plant, the mixing time shall not be less than 50 seconds nor more than 90 seconds.

Mixing of Concrete

• the time elapsed from the time the water is added to the mix until the concrete is deposited in place at the site, shall not exceed 45 minutes when concrete is hauled in non-agitating trucks, nor 90 minutes when hauled in truck mixers.

• when volumetric measurements are authorized for small project requiring less than 75 cu.m. of concrete per day of pouring, the weight proportions shall be converted to equivalent volumetric proportions. Use of chute is allowed provided that a weighing scales for determining the batch weight will be used.

• re-tempering concrete by adding water or by other means shall not be permitted, except that when concrete is delivered in truck mixers, provided all these operations are performed within 45 minutes after the initial mixing operation and the water-cement ratio is not exceeded.

Mixing of Concrete

Limitation of Mixing

• no concrete shall be mixed, placed or finished when the natural light is insufficient, unless an adequate and approved artificial lighting system is operated

• re-tempering of concrete or mortar which has partially hardened that is remixing with or without additional cement, aggregate or water, shall not be permitted.

• if only finishing equipment is carried on the newly paved lane, paving in adjoining lanes may be permitted after 3 days.

Placing of Concrete

• concrete shall be thoroughly consolidated by means of a vibrator inserted in the concrete in a vertical position and should not be operated longer than 15 seconds in any one location.

• vibrators shall operate at a frequency of 8,300 to 9,600 impulses per minute under load and the space interval of inserting vibrators should be between 50 cm to 60 cm.

• vibrators shall be used for consolidation only, and not be used for moving concrete horizontally along the forms.

Placing of Concrete

• concrete not in-place within 90 minutes from the time the ingredients were charged into the mixing drum or that has developed initial set shall not be used.

• a well consolidated concrete is 20 % to 25 % higher in strength than that of concrete which is not thoroughly consolidated

Test Specimens

• as work progresses, at least one (1) set consisting of three (3) concrete beam test specimens, 150 mm x 150 mm x 525 mm shall be taken from each 330 m2 of pavement, 230 mm depth, or fraction thereof placed each day.

• cylinder samples shall not be used as substitute for determining the adequacy of the strength of concrete.

• the beam specimens shall be properly cured and tested at the specified date.

Joints in Portland Cement Concrete Pavement

Longitudinal Joints• deformed steel tie bars of specified length, size, spacing shall be placed perpendicular to the longitudinal joints and may be bent at right angles against the form of the first lane constructed and straightened into final position before the concrete of the adjacent lane is placed.

• tie bars shall not be painted or coated with asphalt or other materials or enclosed in tubes or sleeves.• when shown on the plans and when the adjacent lanes of pavement are constructed separately, joint steel side forms shall be used which will form a keyway along the construction.

Longitudinal Joints

• longitudinal formed joints shall consists of a groove or cleft, extending downward from and normal to the surface of the pavement and shall be continuous and be no gaps in either transverse or longitudinal joints at the intersections of the joints. • longitudinal sawed joints shall be cut by means of approved concrete saws to the depth, width and line shown on the plans and shall be thoroughly cleaned and immediately filled with sealer.

• the longitudinal joints shall be sawed before the end of the curing period or shortly thereafter and before any equipment or vehicles are allowed on the pavement.

Transverse Contraction Joint/ Weakened Joint

• consists of planes of weakness created by forming or cutting grooves in the surface of the pavement and shall include transfer assemblies.• the depth of the weakened plane joint should at all times be less than 50 mm and width should not be more than 6 mm.

Width = 6mm, min.

Depth = 50mm min.

Longitudinal joints

Types of Contraction/Weakened Joint

1. Transverse Strip Contraction Joint

- can be formed by installing a parting strip to be left in place as shown on the plans.

2. Formed Groove Contraction Joint

- shall be made by depressing an approved tool or device into the plastic concrete and shall remain in place until the concrete has attain its initial set and shall then be removed without disturbing the adjacent concrete, unless the device is designed to remain in the joint.

Types of Contraction/Weakened Joint

3. Sawed Contraction Joint

- created by sawing grooves in the surface of the pavement of the width not more than 6 mm and depth of not less than 50 mm and at the spacing and lines as shown on the plans.

- sawing of the joints shall commence as soon as the concrete has hardened sufficiently to permit sawing without excessive raveling, usually 4 to 24 hours.

- sawing of any joint shall be omitted if cracks occurs at or near the joint location prior to the time of sawing.- after each joint is sawed, it shall be thoroughly cleaned and immediately be filled with sealer.

Transverse Construction Joint

• shall be constructed when there is an interruption of more than 30 minutes in the concreting operations.

• if sufficient concrete has been mixed at the time of interruption to form a slab of at least 1.5 m long, the excess concrete from the last preceding joint shall be removed and disposed off as directed.

• no transverse joint shall be constructed within 1.50 m of an expansion joint, or plane of weakness.

Load Transfer Device

• dowel bar of specified size, length and spacing is used in transverse contraction joint as load transfer device to the succeeding plane of weakness and shall be held in position parallel to the surface and center line of the slab that is left in the pavement.

• the portion of each dowel shall be painted with one coat of lead or tar and be thoroughly coated of an approved lubricant to prevent the concrete from binding to that portion of the dowel.

Final Finish

• brooming operation should be executed that the corrugations produced in the surface shall be uniform in appearance and not more than 1.5 mm in depth.

• the hardened surface of the finished pavement shall have a coefficient of friction less than 0.25 or more. Completed pavement that is found to have a coefficient of friction less than 0.25 shall be grounded or scored by the contractor at his own expense to provide the required coefficient of friction.

Surface Test

• the hardened finished pavement shall be tested with a 3-m straight-edge or other specified device.

• areas showing high spots of more than 3 mm but not exceeding 12 mm shall be marked and immediately ground down with an approved grinding tool to an elevation where there area or spot will not show surface deviations in excess of 3 mm when tested with 3 m straight

• areas showing high spots of more than 12 mm, the pavement shall be removed and replaced by and at the expense of the contractor.

• any remaining portion of the slab to be removed and replaced adjacent to the joints that is less than 1.5 m in length, shall also be removed and replaced.

• any area or section to be removed shall not be less than 1.5 m in length and not less than the full width of the lane involved.

Surface Test

Curing

Immediately after the finishing operations have been completed and the concrete has sufficiently set, the surface of the newly placed concrete shall be cured for a period of 72 hours, with any of the following methods:

1. By covering the pavement with cotton or burlap mats saturated with water.

2. By thoroughly wetting the pavement and covering its top surface and sides with waterproof paper.

3. By ponding which involves maintaining a layer of water on the surface of the pavement by means of earth or sand dikes.

4. By spraying uniformly with white pigmented curing compound (Impervious Membrane Method) immediately after finishing of the surface and before the set of concrete has taken place.

Curing

Removal of Forms

• forms for concrete shall remain in place undisturbed for not less than24 hours after concrete pouring.

• in case portions of the concrete are spalled during the removal of forms, they shall be immediately repaired with fresh mortar mixed in the proportioned of one part of Portland Cement and two parts of fine aggregates.

• in case major honeycombs occurs on sides of the pavement, it shall be removed and replaced at the expense of the contractor.

Sealing of Joints

• joints shall be sealed with asphalt sealant soon after the completion of the curing period and before the pavement is opened to traffic.• prior to sealing of joints, it shall be thoroughly cleaned of all foreign materials including membrane curing compound and joint faces and shall be in a surface dry condition when the seal is applied. • the pouring of sealant shall be done in such a manner that the material will not spilled on the exposed surfaces of the concrete. • the use of sand or similar material as a cover for the seal will not be permitted.

Protection of Pavement

• the contractor shall protect the pavement and its appurtenances against both public traffic and traffic caused by his own employees and shall include watchmen to direct the traffic and the erection of and maintenance of warning signs, lights pavement, bridges, etc.

• all boreholes after thickness and/or strength determinations of newly constructed concrete pavements shall be immediately filled/restored with the prescribed concrete mix after completion of the drilling works. ( Dept. Memo Circular No. 97, dated August 9,1991 ) • any damage to the pavement, occurring prior to final acceptance shall be repaired or the pavement shall be replaced.

Acceptance of Concrete

• the strength level of the concrete will be considered satisfactory if the averages of all sets of three (3) consecutive strength test results equals or exceed the specified strength and no individual strength test result is deficient by more than 15 % of the specified strength. • Concrete deemed to be not acceptable using the above criteria may

be rejected unless the contractor can provide evidence, by means of core tests, that the quality of concrete represented by failed test is acceptable in place.

• Concrete in the area represented by the cores will be considered adequate if the average strength of the cores is equal to at least 85% of and if no single core is less than 75% of the specified strength.

Acceptance of Concrete

• if the strength of control specimens does not meet the strength requirements and it is not advisable to obtain cores from the structure due to structural considerations, payment of the concrete will be made at an adjusted price due to strength deficiency of concrete specimens as specified hereunder:

Deficiency in Strength of Concrete Specimens Percent (%) of Contract Percent (%) Price Allowed

Less than 5 100

5 to less than 10 80




25 or more 0

Opening to Traffic

• the concrete pavement will not be opened to traffic until the test specimens molded and cured have attained the minimum strength requirements.

• if tests are not conducted prior to the specified age, the pavement shall not be operated to traffic until 14 days after the concrete was placed.

Tolerance and Pavement Thickness

• the completed pavement shall be accepted on a lot basis when :

a. Pavement length of 1000 lm when single lane is poured.

b. Pavement length of 500 lm when two lanes are poured concurrently.

c. The last unit in each slab constitutes a lot in itself when its length is at least ½ of the normal length, however, if it is shorter than ½ of the normal length, it shall be included in the previous lot.

• the thickness of the pavement will be determined by measurement of cores from the completed pavement.

e. Each lot will be divided into five (5) equal segments and one core will be obtained from each segment.

d. Other areas such as intersections, entrances, cross-overs, ramps, etc., will be grouped together to form a lot.

Tolerance and Pavement Thickness

Rules in Calculating the Average Thickness of Pavement

1. Individual measurements which are in excess of the specified thickness by more than 5 mm will be considered as the specified thickness plus 5 mm

2. Measurement which are less than the specified thickness by more than 25 mm shall not be included in the average.

3. When the average thickness for the lot is deficient, the contract unit price will be adjusted for thickness.

4. When measurement of any core is less than the specified thickness by more than 25 mm, the actual thickness of the pavement in this area will be determined by taking additional cores at no less than 5 m intervals parallel to the centerline in each direction from the affected location until a core is found in each direction, which is not deficient by more than 25 mm.



5. The area of slab for which no payment will be made shall be the product of the paving width multiplied by the distance along the center line of the road between transverse sections found not deficient in thickness by more than 25 mm .

6. The remainder of the segment to be used to get the average thickness of each lot shall be determined by taking the average thickness of additional cores which are not deficient by more than 25 mm .

Adjustment for Thickness

Deficiency in the Average Thickness, per lot (mm)

Percentage Contract Price Per Lot

• when the average thickness of the pavement per lot is deficient payment for the lot shall be adjusted as follows:

0 – 5 100% payment 6 – 10 95% payment

11 – 15 85% payment

16 – 20 70% payment

21 – 25 50% paymentMore than 25 Remove and replace/No Payment

Method of Measurement

• the area to be paid under this item shall be the number of square meters (m2) of concrete pavement placed and accepted in the completed pavement

• the width for measurements will be the width from outside edge to outside edge of completed pavement as placed

• the length will be measured horizontally along the centerline of each roadway or ramp

Basis of Payment

The accepted quantity, measured shall be paid for at the contract unit price for Portland Cement Concrete Pavement, which price and payment shall be full compensation for preparation of road bed and finishing of shoulders, unless otherwise provided by the Special Provision, furnishing all materials, for mixing, placing, finishing and curing all concrete, for furnishing and placing all joint materials, for sawing weakened plane joints, for fitting the pre-fabricated center metal joint, for facilitating and controlling traffic and for furnishing all labor, equipment, tools and incidentals necessary to completed the item.

ITEM DESCRIPTION

• This item shall consist of furnishing, placing and finishing concrete in all structures except pavements in accordance with this Specification and conforming to the lines, grades and dimensions shown on the plans.

• Concrete shall consist of a mixture of Portland cement, fineaggregate, coarse aggregate, admixture, when specified and water in proportions specified or approved by the Engineer.

Classes and Uses of Structural Concrete

Class B - Footings, pedestals, massive pier shafts, pipe bedding, and gravity walls, unreinforced or with only a small reinforcement

Class C - Thin reinforced sections, railings, precast R.C. piles and cribbing and for filler in steel grid

floors Class P - Prestressed concrete structures and members

Seal - Concrete deposited in water

Class A - All superstructures and heavily reinforced substructures such as slabs, beams, girders, columns, arch ribs, box culverts, reinforced abutments, retaining walls and reinforced footings.

MATERIALS REQUIREMENTS

Portland Cement

• Type I Portland Cement shall be used unless otherwise provided for in the Special Provisions

• Use of Portland Pozzolan Cement Type IP meeting the requirements of AASHTO M 240/ASTM C 695, Specifications for Blended Hydraulic Cement shall be allowed, provided that trial mixes shall be done and that the mixes meet the concrete strength requirements.

Fine Aggregates

• It shall consist of natural sand, stone screenings or other inert materials with similar characteristics, or combinations, thereof, having hard, strong and durable particles.

• It shall not contain more than three (3) mass percent of material passing the 0.075 mm (No. 200 sieve) by washing nor more than one (1) mass percent each of clay lumps or shale.

• When tested for the effect of organic impurities of strength of mortar by AASHTO T 71, the fine aggregates may be used if the relative strength at 7 and 28 days is not less than 95 mass percent.

• When subjected to five (5) cycles of the sodium sulfate soundness test the weighted loss shall not exceed 10 mass percent

Fine Aggregates

Grading Requirements for Fine Aggregates


9.5 mm ( 3/8 in. ) 100

4.75 mm ( No. 4 ) 95 - 100 2.36 mm ( No. 8 ) -

1.18 mm ( No. 16 ) 45 - 80

0.600 mm ( No. 30 ) - 0.300 mm ( No. 50 ) 5 - 30

0.150 mm ( No. 100 ) 0 - 10

Coarse Aggregates

• It shall consist of crushed stone, gravel, blast furnace slag, or other approved inert materials of similar characteristics or combinations thereof, having hard, strong, durable pieces and free from any adherent coatings.

• It shall contain not more than one (1) mass percent of materials passing the 0.075 mm (No. 200 Sieve), nor more than 0.25 mass percent of clay lumps, nor more than 3.5 mass percent of soft fragments.

• If subjected to five (5) cycles of the sodium sulfate soundness test, the weighted loss shall not exceed 12 mass percent.

• It shall have a mass percent of wear not exceeding 40 when tested by AASHTO T 96.

Coarse Aggregates

Grading Requirements for Coarse Aggregates


Standard Alternative Class A Class B Class C Class PClass Seal

63.0 2 – 1/2 in - 10050.0 2 in 100 95 - 10037.5 1-1/2 in 95–100 - 10025.0 1 in - 35-70 100 95-10019.0 34 in 35-70 - 100 95 - 100 -12.5 1/2 in - 10-30 90-100 - 25-609.5 3/8 in 10-30 - 40-70 20-55 -

4.75 No. 4 0-5 0-5 0-15 0-10 0-10

Water

• It shall be reasonably clean and free of oil, salt, acid, alkali, grass of other substances, injurious to the finished product.

• water which is drinkable may be used without test.

• where the source is shallow, the intake shall be so enclosed as to exclude silty, mud, grass or other materials.

Reinforcing Steel

• it shall conform to the requirements of AASHTO M 31 (ASTM A 615) – Deformed Billet – Steel Bars for Concrete Reinforcement

• bar reinforcement for concrete structures, except No. 2 bars shall be deformed in accordance with AASTHO M 42, M 31 and M 53 for Nos. 3 through 11.

• specification requires the use of structural or intermediate grades of steel with suitable chemical composition, tensile and bending properties.

• reinforcing steel should be clean and free of loose rust or mill scale when concrete is placed.

Admixtures

• air-entraining admixtures shall conform to the requirements of AASHTO M 154

• chemical admixtures such as water-reducing, set-retarding and set accelerating or combinations thereof, shall conform to the requirements of AASHTO M 194

• admixtures are used in concrete to improve concrete properties, to aid in construction procedures, to provide economy and to fulfill other special purposes.

• the effectiveness of an admixtures depends upon such factors as type, brand, and amount of cement, water content; aggregate shape, gradation and proportions; mixing time; slump; and temperatures of concrete and air.

Concrete Properties Commonly Modified By Admixtures

1. Rate of hydration or setting time2. Workability3. Dispersion4. Air-entrainment

Commonly Used Admixtures In Concrete Construction• Accelerators - used to speed up the initial set of concrete

These are added to concrete either:

a. to increase the rate of hydration of cement, and hence to increase the rate of development of strength, or b. Shorten the setting time

• Retarders

Commonly Used Admixtures In Concrete Construction

also used to reduce the incidence of thermal cracking and to maintain concrete workability during large pours or long ready-mix hauls.

used to slow down the setting of concrete and can delay initial setting time up to 4 hours

useful in concreting during hot weather, when the normal setting time is shortened by the higher temperature, and in preventing the formation of cold joints.

Water - Reducers


water reducers or plasticizers are used to :a. Obtain a higher strength by decreasing the water- cement ratio at the same workability as an ordinary mix;

b. Achieve the same workability by decreasing the cement content; and

c. Increase the workability so as to ease placing of mix in inaccessible locations.

the reduction in the quantity of mixing water varies between 5 and 15 percent.

Superplasticizers new type of water-reducing admixtures that are used to produce flowing concrete which is useful for placing in very heavily reinforced sections, inaccessible locations, or where very rapid placing is required.

another use of superplasticizers is in the production of concrete of normal workability but with an extremely high strength due to a very low water/cement ratio.

superplasticizers can reduce the water content by 25 to 35 percent, and increase the 24-hour strength by 50 to 70 percent.


Air – entraining Admixtures these admixtures help incorporate a controlled amount of air in the form of minute bubbles (approximately 0.01 to 0.25 mm diameter) in concrete during mixing, without significantly altering the setting or the rate of hardening characteristics of concrete.

air-entrained concrete is used where improved workability, easier placing, and increased durability are required and also useful in making lightweight aggregate concrete


air-entrainment, while improving the durability and plasticity, may have an adverse effect on the strength of concrete. Within the normal range of air content, the maximum reduction in compressive strength and flexural strength rarely exceeds 15 to 10 percent, respectively.


Curing Materials

• Curing materials for concrete such as cotton mats, burlap cloth, water-proof paper, liquid membrane forming compounds or sheeting (film) materials shall conform to the requirements of AASHTO M 182, AASHTO M 171 and AASHTO M 148, respectively

• curing means preventing or delaying drying up of intrinsic moisture inside the capillaries of concrete for adequate hydration of cement in the mix in order that it may continue to gain strength.

• immediately after the finishing operations have been completed and the concrete has sufficiently set, the surface of the newly placed concrete shall be cured for a period of 72 hours with any of the methods as in Item 311-Portland Cement Concrete Pavement.

Curing Materials

Elastomeric, Compression Joint Seals

• It shall conform to the requirements of AASHTO M 220

Elastomeric Bearing Pads

• It shall conform to the requirements of AASHTO M 251

• the main function of these material is to transfer loads or accommodate relative movement between a bridge structure and its supporting structure, or both while avoiding damaging strain and additional tension.

• For classification and use, material requirements, physical requirements, construction requirements, refer to Item No. 412 – Elastomeric Bearing Pads

Sampling and testing of Structural Concrete

• As work progresses, at least one (1) sample consisting of three (3) concrete cylinder test specimens; 150 mm x 300 mm (6 x 12 inches), shall be taken from each 75 cubic meters of each class of concrete or fraction thereof placed each day.

• the cylinder shall be prepared, cured and tested at the specified date.

Composition and Strength of Concrete for Use in Structures

Class of Concrete

Min. Cement Content per m3

kg (bag**)

Max. Water/Cement

Ratio kg/kg

Consistency Range in Slump

Mm (inch)

Designated Size of Coarse

AggregateStd. Mm (inch)

Min. Compressive Strength of Concrete

Cylinder Specimens @ 28 days

MN/m2 (psi)A 360 0.53 50 – 100 37.5 – 4.75 20.7

(9 bags) (2 – 4) (1-1/2 – No. 4) (3,000)

B 320 0.58 50 – 100 5.0 – 4.75 16.5

(8 bags) (2 – 4) (2” – No. 4) (2,400)

C 380 0.55 50 – 100 12.5 – 4.75 20.7

(9.5 bags) (2 – 4) (1/2” – No. 4*) (3,000)

P 440 0.49 100 max 19.0 – 4.75 37.7

(11 bags) (4 max.) (3/4” – No. 4*) (5,000)

Seal 380 0.58 100 – 200 25 – 4.75 20.7

(9.5 bags) (4 – 8) (1” – No. 4*) (3,000)* The measured cement content shall be within plus or minus and mass percent of the

design cement content

** Based of 40 kg/bag

Consistency of Concrete

• concrete shall have a consistency such that it will be workable in the required position.• it shall have a consistency that will flow around reinforcing steel but individual particles of the coarse aggregates when isolated shall show a coating of mortar containing its proportionate amount of sand. • the consistency of concrete shall be gauged by the ability of the equipment to properly place it and not by the difficulty in mixing and transporting.• consistency of the mixture shall be checked frequently by means of the slump test.

Mixing and Delivery of Concrete

• Concrete may be mixed at the site of construction, at a central plant or by a combination of central plant and truck mixing or by a combination of central plant and truck agitating.

• concrete mix when supplied by a batching plant, shall only be allowed in the DPWH projects provided it is duly accredited by the BRS ( DO # 253, S. of 2003 ). • batching plants installed/used in the DPWH contract projects shall also be required to be accredited prior to supply of the concrete mix.

• when volumetric measurements are authorized for small project requiring less than 75 cu.m. of concrete per day of pouring, the weight proportions shall be converted to equivalent volumetric proportions. • concrete mixing, by chute is allowed provided that a weighing scales for determining the batch weight will be used.


• the intervals between delivery of batches shall not be so great as to allow the concrete inplace to harden partially, and in no case shall such an interval exceed 30 minutes.

• mixing time shall be measured from the time all materials, except water, are in the drum and shall not be less than 60 seconds for mixers having a capacity of 1.5 cu.m. or less. While for mixers having a capacity greater than 1.5 cu.m., the mixing time shall not be less than 90 seconds.

• mixer having a rated capacity of less than a one-bag batch shall not be used and the volume of concrete mixed per batch shall not exceed the mixer’s nominal capacity.



• Re-tempering concrete will not be permitted.

• All concrete shall be mixed for a period of not less than 1-1/2 minutes after all materials, including water are in the mixer.

• Admixtures for increasing the workability, for retarding the set or improving characteristics of the concrete will be permitted only when specifically provided for in the contract, or authorized in writing by the Engineer.

• Concrete shall not be placed until forms and reinforcing steel have been checked and approved by the Engineer.

• To avoid segregation of the materials and the displacement of the reinforcement, the use of long troughs, chutes and pipes for conveying concrete to the forms shall be permitted only on written authorization of the Engineer.

Placing of Concrete

• Open troughs and chutes shall be of metal lined, where steep slopes are required, the chutes shall be equipped with baffles or be in short lengths that reverse the direction of movement to avoid segregation.

• Concrete during and immediately after placing shall be thoroughly compacted., The concrete in walls, beams, columns and the likes shall be placed in horizontal layers not more than 30 cm thick.

Placing of Concrete

• Vibrators shall be inserted into and withdrawn slowly and vertically from the concrete to penetrate underlying lift for

homogeneity between lifts.

• a well consolidated concrete is 20% to 25% higher than that of concrete which is not thoroughly consolidated.

• Joints in the concrete due to stopping work shall be avoided as much as possible. When placing of concrete is temporarily discontinued, the concrete, after becoming firm enough to retain its shape, shall be cleaned of laitance and other objectionable materials to a sufficient depth to expose sound concrete.

• the time of consolidation/compaction of structural concrete must not exceed 15 seconds and the space interval of inserting vibrators should be between 50 cm to 60 cm.

Placing of Concrete

• Application of vibrators shall be at points uniformly spaced, and not further apart than twice the radius over which the vibration is visibly effective.

Curing of Concrete

Curing of concrete shall be done by any of the following method:1. Water Method• The concrete shall be kept continuously wet by the application of

water for a minimum period of 7 days after the concrete has been placed. Cotton mats, rugs, carpets, or earth or sand blankets may be used to retain the moisture.

2. Curing Compound• Surfaces exposed to the air may be cured by the application of an

impervious membrane and shall be practically colorless liquid. The compound shall be applied with a pressurized spray to cover the entire concrete surface with a uniform film and shall be of such character that it will harden within 30 minutes after application.

Curing of Concrete

3. Waterproof Membrane Method

• The exposed finished surfaces of concrete shall be sprayed with water, using a nozzle that so atomizes the flow that a mist and not a spray is form until the concrete has set, after which a curing membrane of waterproof paper or plastic sheeting shall be placed.

• Curing membrane shall remain in place for a period of not less than 72 hours.

Curing of Concrete

4. Forms – in-place Method

• Formed surfaces of concrete may be cured by retaining the form-in-place and shall remain in place for a minimum period of 7 days after the concrete has been placed, except that for members over 50 cm in least dimensions, the form shall remain in-place for a minimum period of 5 days. Wooden forms shall be kept wet by watering during the curing period.

• to prevent moisture loss on exposed surfaces during the pre-steaming period, members shall be covered immediately after casting or the exposed surface shall be kept wet by fog spray or wet blankets.

• After placement of the concrete, members shall be held for a minimum 4 hours pre-steaming period.

• this method is applicable on pre-cast concrete members.5. Steam Curing Method

Curing of Concrete

Removal of Forms and Falsework

• when concrete strength tests are used for removal of forms and supports, such removal should not begin until the concrete has attained the percentage of the specified design strength as shown below:

Part of Concrete Structure Minimum Time Min. % Design Str.

Centering under Girders, Beams Frames or Arches 14 days 80 % Floor Slabs 14 days 70 %

Walls 1 day 70 %

Columns 2 days 70 %

Sides of Beams and all other Vertical surfaces 1 day 70 %

• forms and false work shall not be removed without the consent of the Engineer.

Method of Payment

The quantity of structural concrete to be paid for will be the final quantity placed and accepted in the completed structure. No deductions will be made for the volume occupied by pipe less than 100 mm (4 inches) in diameter or by reinforcing steel, anchors, conduits, weepholes or expansion joint materials

Basis of Payment

• payment shall constitute full compensation for furnishing, placing and finishing concrete including all labor, equipment, tools and incidentals necessary to complete the work prescribed in the item.

• Payment will be made under :

Pay Item No. Description Unit of Measurement

405 (1) Structural Concrete, Class A Cubic Meter

405 (2) Structural Concrete, Class B Cubic Meter 405 (3) Structural Concrete, Class C Cubic Meter405 (4) Structural Concrete, Class P Cubic Meter 405 (5) Seal Concrete Cubic Meter

Item Description

A structure which is built of stone only or stone, cement, fine aggregates and water, with or without filter backing which is commonly used in slope protection works, drainage canals and other places as called for in the plans, and constructed on the prepared foundation bed in accordance with the lines and grades, sections and dimensions shown on the plans.

Materials Requirements

Stones – consist of rock as nearly rectangular in section as is practical, except that riprap of Class A may consist of round natural stones. The stones shall be sound, tough, durable, dense, resistant to the action of air and water, and suitable in all respects for the purpose intended.

- Sound pieces of concrete obtained from the removal of bridges, culverts and other structures may be substituted for stone with the approval of the Engineer.

Classes of Stones Intended for Riprap

Class A - Stones ranging from a minimum of 15 kg to a maximum of 25 kg., with at least 50 percent of the stones weighing more than 20 kg.

Class B - Stones ranging from a minimum of 30 kg to a maximum of 70 kg. with at least 50 percent of the stones weighing more than 50 kg.

Class C - Stones ranging from a minimum of 60 kg to a maximum of 100 kg with at least 50 percent of the stones weighing more than 80 kg.

Class D - Stones ranging from a minimum of 100 kg to a maximum of 200 kg with at least 50 percent of the stones weighing more than 150 kg.

Mortar

• shall consists of sand, cement and water conforming to the requirements under Item 405 – Structural Concrete.

• shall be mixed in the proportion of one part cement to three parts sand by volume and sufficient water to obtain the required consistency

• Portland Cement Type I conforming to the requirements of AASHTO M 85 (ASTM C 150) shall be used.

• Use of Portland Pozzolan Type IP meeting the requirements of AASHTO M 240 (ASTM C 595) Specifications for Blended Hydraulic Cement shall be allowed, provided that trial mix shall be done and that the mixes meet the strength requirement.

Grading Requirements for Structural Concrete

• Fine aggregates shall conform to the requirements as specified in Item 405, Structural Concrete and have the following grading requirements:


9.5 mm ( 3/8 ) 100 4.75 mm ( No.4 ) 95 - 100

2.36 mm ( No. 8 ) - 1.18 mm ( No.16 ) 45 - 80

0.600 mm ( No. 30 ) -

0.300 mm ( No. 50 ) 5 - 300.150 mm ( No. 100 ) 0 - 10

Mortar

Mortar

• the horizontal and vertical contact surface between stones shall be embedded by cement mortar having a minimum thickness of 20 mm. • sufficient mortar shall be used to completely fill all voids leaving the face of the stones exposed.

Filter Materials

• when required, the riprap shall be placed on a filter layer to prevent fine embankment materials to be washed out through the voids of the faces of stones.

• if not so specified, fine aggregate passing the grading requirements for Item 405, Structural Concrete, will satisfy for the filter materials.

• the grading of the filter material shall be specified on the Plans or in the Special Provisions.

Filter Materials

Construction Requirements

• the bed for riprap shall be excavated to the required depths and properly compacted, trimmed and shaped.

• stones placed below the water line shall be distributed so that the minimum thickness of the riprap is not less than that of the specified.

• stones above the water line shall be placed by hand or individually by machines and they shall be laid with close, broken joints and shall be firmly bedded into the slope and against the adjoining stones.

• Stones shall be laid with its larger axis perpendicular to the slope in close contact with each adjacent stone.

• For dry riprap, interstices between stones shall be filled with small broken fragments firmly rammed into place

• For grouted riprap, spaces between the stones shall be filled with cement mortar throughout the thickness of the riprap and sufficient mortar shall be used to completely fill all voids except that the face surface of the stone shall be left exposed.

• Grouted riprap shall be cured for a period of at least three (3) days.

• the surface of riprap shall not vary from the theoretical surface by more than 100 mm at any point.



• Riprap shall have the following minimum thickness, measured perpendicular to the slope

Class D - 800 mm

Class A - 300 mm

Class B - 500 mm

Class C - 600 mm


• weepholes shall be placed horizontally at the lowest points where free outlets for water can be obtained and shall be spaced at not more than 2 m center to center in a staggered manner.

• the length of the weepholes shall not be less than the thickness of the walls of the completed riprap and shall be at least 50 mm diameter PVC or other pipe materials acceptable to the Engineer

• weepholes must be provided with filter bags as specified in the plans, special provisions or as directed by the Engineer.

Method of Measurement

• the quantities to be measured for payment shall be the number of cubic meters of riprap or grouted riprap as the case may be, including stones placed in the toe trench laid in position and accepted.

• filter layer of granular material, when required, shall be measured separately by the cubic meter in place and accepted.

Basis of Payment

It shall be paid for at the contract unit price which price and payment shall be full compensation for excavation and preparation of the bed, for furnishing and placing all materials including backfill and all additional fill to bring the riprap bed up to the lines, grades and dimensions as shown on the plans, and all labor equipment, tools and incidentals necessary to complete the item.

Payment shall be made under:

Basis of Payment

Pay Item No. Description Unit of Measurement

505 (1) Riprap, Class A Cubic Meter

505 (2) Riprap, Class B Cubic Meter 505 (3) Riprap, Class C Cubic Meter

505 (4) Riprap, Class D Cubic Meter

505 (5) Grouted Riprap, Class A Cubic Meter

505 (6) Grouted Riprap, Class B Cubic Meter

505 (7) Grouted Riprap, Class C Cubic Meter

505 (8) Grouted Riprap, Class D Cubic Meter

505 (9) Filter Layer of Granular Matls. Cubic Meter

THANK YOU ! ! !Maraming Salamat po!

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