highway material experiments

8/8/2019 highway material experiments

1/138

CE320 Highway MaterialsCE320 Highway Materials

Testing ExperimentsTesting Experiments

ByDr. Tom. V. Mathew

IIT Bombay


2/138

Overview

Pavement materials

Soil (sub-grade, embankment)

Aggregates (coarse, fine)

Binders (Bitumen, cement)


3/138

Soil

Soil is all unindurated mineral material lying above rock strataincluding air, water, and organic matter

It is non-homogeneous and porous

Properties greatly influenced by moisture, density andcompaction


4/138

Soil

Soil is a very essential highway material

1. Soil sub grade is part of the pavement

structure; the design and behaviour of

pavement depends to a great extent on the sub

grade properties

2. Soil is one of the principal materials of

construction in stabilized soil base and sub

base and also in embankment construction


5/138

Properties of soil

Shape of soil particles (bulky, flaky)

Particle size classification (clay, silt, sand, gravel)

Gradation of soil

Porosity and void ratio

Soil density (dry and wet density)


6/138

Properties of soil

Moisture-density relationship (Proctor density, OMC)

Chemical properties (Organic matter, minerals, pH)

Soil-water (Capillary water, water table)

Physical properties (Permeability, compressibility, shear

resistance)


7/138

Properties of soil

Atterberg limits (Index properties)

Liquid limit : Moisture content at which state changes from

viscous liquid to plastic solid

Plastic limit : Moisture content at which state changes from

plastic solid to semi solid state

Plasticity index : Range during which it acts as plasticPI = LL PL

Liquidity index : (NMC PL) / PI


8/138

Desirable Properties of soil

Stability: Adequate stability to resist permanent

deformation under loads

Incompressibility: Minimum variation in volume

ensures minimum differential expansion and

strength values

Permanency of Strength: Should retain desired

subgrade support i.e. resistance to weathering


9/138

Minimum changes in volume and stabilityunder adverse conditions of weatherand ground water

Good drainage: Essential to avoidexcessive moisture retention and toreduce the potential

frost action

Ease of compaction: Ensures higher drydensity and strength under particulartype and amount of compaction

Desirable Properties of soil


10/138

Bitumen is a petroleum product obtained by thedistillation of petroleum crude

Bitumen is a hydrocarbon material of either natural or

pyrogenous origin, found in gaseous, liquid, semisolid or

solid form

Highway construction: hydrocarbon material which are

cementitious in character

Bitumen


11/138

Bitumen

1. Natural product (lake asphalt, rock asphalt)

2. Fractional distillation of petroleum

a. Asphalt cement (Penetration grade)

b. Oxidised asphalt (softening point grade)

c. Liquid asphalt

3. Tar: destructive distillation of coal


12/138

Cutback: the viscosity of bitumen reduced byvolatile diluents: slow, medium, rapid curing

Emulsion: bitumen is suspended in finely divided

condition in an aqueous medium and stabilized

with an emulsifier : slow, medium, rapid setting

Liquid Bitumen


13/138

1. Normal Bitumen

Production

The portion of bituminous material present inpetroleum may widely differ depending on the source

Almost all the crude petroleum's contain considerableamounts of water along with crude oil

Hence the petroleum should be dehydrated before the

distillation


14/138

Petroleum Bitumen Flow Chart


15/138

Types of Distillation Processes

Fractional distillation:

2. In the fractional distillation the various volatile

constituents are separated at successively higher

temperatures without substantial chemical change

4. The fractions obtained yield gasoline, naphtha,

kerosene and lubricating oil

3. The residue would be petroleum bitumen

4. In destructive distillation material undergoes chemical

changes under the application of extreme heat and

pressure


16/138

Steam distillation:

2. Steam distillation is employed to produce steam

refined petroleum bitumen without causing

chemical change

4. When the residue is distilled to a definite

consistency without further treatment it is called

as Straight-run Bitumen


17/138

It should be fluid enough at the time of mixing to

coat the aggregate evenly by a thin film

It should have low temperature susceptibility

It should show uniform viscositycharacteristics

Bitumen should have good amount of volatiles in

it, and it should not lose them excessively when

subjected to higher temperature

Desirable Properties of Bitumen


18/138

The bitumen should be ductile and not brittle

The bitumen should be capable of being heated to thetemperature at which it can be easily mixed without anyfire hazards

The bitumen should have good affinity to the aggregateand should not be stripped off in the continued presenceoff water

Desirable Properties of Bitumen


19/138

Aggregate

Aggregate is the major component of all

materials used in road construction

It is used in granular bases and sub base,

bituminous courses and in cement concrete

pavements


20/138

Desirable properties of Aggregate

Strength:The aggregate should be sufficiently strong towithstand the stresses due to traffic wheel load

Hardness: Aggregate should have hard enough to resist

the wear due to abrasive action of traffic

Toughness: Aggregate should have resistance to impact

or toughness


21/138

Continue.

Durability: The aggregate used in pavementshould resistance to disintegration due to theaction of weather

Shape of aggregate: Should not be Flakyand elongated

Adhesion with Bitumen: Should have goodaffinity to bitumen


22/138

Quality Control Tests: Soil

1. Gradation

2. Atterberg Limits and indices (LL, PL,PI, SL)

3. Laboratory Compaction (MDD and OMC)

4. Field density test

5. CBR Test (Demo)

6. Plate bearing test


23/138

Quality control tests: Aggregate

1. Sieve analysis

2. Aggregate crushing test

3. Aggregate impact test

4. Abrasion Test (L.A. abrasion test)

5. Shape test (FI, EI, Angul. No.)

6. Soundness Test

7. Specific gravity and Water absorption test

8. Stripping value test


24/138

1. Penetration

2. Ductility

3. Softening point

4. Specific gravity

5. Loss on heating

6. Flash & Fire point

7. Viscosity (Demo)8. Solubility

Quality control tests: Bitumen


25/138

California bearing ratio (CBR)

A simple test that compares the bearingcapacity of a material with that of a well-graded

crushed stone

A high quality crushed stone material should

have a CBR of about 100%

CBR is basically a measure of strength


26/138

CBR

The California Bearing Ratio (CBR) test was developed by theCalifornia Division of Highways in 1929 as a method ofclassifying the suitability of a soil for use as a subgrade or basecourse materials in highway construction

During World War II, the U.S. Corps of Engineers adopted thetest for use in airfield construction

The test is empirical and results cannot be related accuratelywith any fundamental property of the material.


27/138

CBR

CBR value is the measure of resistance ofmaterial to the penetration of standard plunger

under controlled density and moisture

condition.

The CBR test can be made in the laboratory on

undisturbed or remoulded soil samples.

The CBR value of sub grade is normally

evaluated on a soaked sample compacted at

optimum moisture content to maximum dry

density.


28/138

Basic Test

This consists of causing a plunger of 50 mmdiameter to penetrate a soil sample at the rate of1.25 mm/min.

The force (load) required to cause the penetration is

plotted against measured penetration.

The loads at 2.5 mm and 5 mm penetration arerecorded.

This load corresponding to 2.5 mm or 5 mmpenetration is expressed as a percentage ofstandard load sustained by the crushed aggregatesat the same penetration to obtain CBR value.


29/138

Definition of CBR

California bearing ratio is defined as theratio (expressed as percentage) between

the load sustained by the soil sample at a

specified penetration of a standard

plunger (50 mm diameter) and the load

sustained by the standard crushed stones

at the same penetration.


30/138

Standard Load values on Crushed Stones for

Different Penetration Values

183360012.5

162318010.0

13426307.5

10520555.0

7013702.5

Unit Standard

Load, kg/cm2Standard

Load, kg

Penetration,

mm


31/138

Apparatus

Loading frame

Cylindrical mould, Collar, Base Plate and

spacer Disc

Compaction hammer

Expansion Measuring Apparatus - Perforated

plate with adjustable stem, tripod and dial

gauge reading to 0.01 mm

Annular Surcharge Weights


32/138

Loading Machine

With a capacity of at least5000 kg and equipped

with a movable head or

base that travels at an

uniform rate of 1.25

mm/min.


33/138

Cylindrical Mould

Cylindrical mould withinside diameter 150 mm

and height 175 mm,

provided with a

detachable extension

collar 50 mm height and

a detachable perforated

base plate 10 mm thick.


34/138

Compaction Rammer

Weight 2.6 kg with adrop of 310 mm

(or) Weight 4.89 kg a

drop 450 mm.

Adj t bl t f t d l t t i d


35/138

Adjustable stem, perforated plate, tripod

and dial gauge


36/138

Annular Weights

One annular metal weightand several slotted

weights weighing 2.5 kg

each, 147 mm in

diameter, with a central

hole 53 mm in diameter.


37/138

P ti f T t S i


38/138

Preparation of Test Specimen

Prepare the remoulded specimen at Proctorsmaximum dry density or any other density at

which C.B.R is required. Maintain the

specimen at optimum moisture content or thefield moisture as required. The material used

should pass 20 mm I.S. sieve. Prepare the

specimen either by dynamic compaction or bystatic compaction.

D i C ti


39/138

Dynamic Compaction

Take about 4.5 to 5.5 kg ofsoil and mix thoroughly with

the required water.

Just before making the

compacted mould of soil, takerepresentative sample for

determining water content.

Fix the extension collar and

the base plate to the mould.Insert the spacer disc over

the base. Place the filter

paper on the top of the

spacer disc.

Dynamic Compaction


40/138

Dynamic Compaction

Compact the soil in themould using either lightcompaction or heavycompaction. For light

compaction, compact thesoil in 3 equal layers,each layer being given 55blows by the 2.6 kg

rammer. For heavycompaction compact thesoil in 5 layers, by giving56 blows to each layer by

the 4.89 kg rammer.

Dynamic Compaction


41/138

Dynamic Compaction

Remove the collar and trim the specimensmooth and flush with the mould.

Remove the base plate and the displacer disc,

weigh the mould with compacted soil, anddetermine the wet unit weight.

Place a filter paper on the base plate, invert

the specimen (5 cm gap is on the top) andattach the base plate so that the soil is in

contact with the filter paper on the base.


42/138

Static Compaction

Calculate the weight of the wet soil at the required watercontent to give the desired density when occupying the

standard specimen volume in the mould from the

expression.

W= (1+w)*V*d

Where,

W= Weight of the wet soil, gm

w= desired water content

V= volume of the specimen in the mould, cc

= 2209 cc

d= required dry density in gm/cc


43/138

Static Compaction

Place correct weight (W) of the soil in the mould.Place a filter paper and the spacer disc on the top of

soil.

Keep the mould assembly in static loading frame andcompact by pressing the spacer disc till the level of disc

reaches the top of the mould.

Keep the load for some time and then release the load.

Remove the spacer disc.

The test may be conducted for both soaked as well as

unsoaked conditions.


44/138


45/138

Penetration Test

Place the mould assembly with the surcharge weights on thepenetration test machine.

Seat the penetration piston at the center of the specimen withthe smallest possible load, but in no case in excess of 4 kg sothat full contact of the piston on the sample is established.

Set the stress and strain dial gauge to read zero. Apply the loadon the piston so that the penetration rate is about 1.25 mm/min.

Record the load readings at penetrations of 0.5, 1.0, 1.5, 2.0,2.5, 3.0, 4.0, 5.0, 7.5, 10 and 12.5 mm. Note the maximum load

and corresponding penetration if it occurs for a penetration lessthan 12.5 mm.

Detach the mould from the loading equipment. Take about 20 to50 g of soil from the top 3 cm layer and determine the moisturecontent.


46/138


47/138

Data from a Typical CBR Test for


48/138

75

72

69

58

50

38

Proving

Ring

Readin

g

(div)

49.95

33.30

18.50

11.10

3.70

0

Load

on

Plunger

12.5

10

7.5

5

4

3

Penetratio

n

(mm)

138.75

133.20

127.65

107.30

92.50

70.30

Load

on

Plunger

272.5

182

101.5

61

20.5

00

Proving

Ring

Reading

(div)

Penetratio

n

(mm)

Data from a Typical CBR Test for

Sample No.1

Load Vs Penetration Curve for


49/138

0

20

40

60

80

100

120

140

160

0 2.5 5 7.5 10 12.5

Penetration

Load

Load Vs Penetration Curve for

Sample No.1


50/138

Initial Concavity

The load penetration curve may show

initial concavity due to the following

reasons:The top layer of the sample might have become

too soft due to soaking in water

The surface of the plunger or the surface of thesample might not be horizontal


51/138

Correction

Draw a tangent to the load-penetration curve

where it changes concavity to convexity

The point of intersection of this tangent line

with the x-axis is taken as the new origin

Shift the origin to this point (new origin) and

correct all the penetration values

Corrected Penetration Values for


52/138

Corrected Penetration Values for

Sample No.1

0

20

40

60

80

100

120

140

160

0 2.5 5 7.5 10 12.5

Penetration, mm

Load,

kg

2.5 5


53/138

Computation of CBR for Sample No.1

Compute CBR at 2.5 mm penetrationCBR of Specimen at 2.5 mm penetration =

(80/1370)*100 = 5.84 %

Compute CBR at 5 mm penetration

CBR of Specimen at 5 mm penetration =

(117/2055)*100 = 5.69 %


54/138

Variation in CBR Values

At least three samples should be tested oneach type of soil at the same density and

moisture content to take care of the variation in

the valuesThis will enable a reliable average value to be

obtained in most cases

Where variation with in CBR values is morethan the permissible maximum variation the

design CBR value should be the average of six

samples and not three


55/138

Permissible Variation in CBR Value

531 and above

311-30

25-10

15

Maximum variation

in CBR value

CBR (per cent)


56/138

Design CBR

The average CBR values corresponding to 2.5 mm and5 mm penetration values should be worked out

If the average CBR at 2.5 mm penetration is more than

that at 5 mm penetration, then the design CBR is theaverage CBR at 2.5 mm penetration

If the CBR at 5mm penetration is more than that at 2.5

mm penetration, then the test should be repeated. Even

after the repetition, if CBR at 5mm is more than CBR at2.5 mm, CBR at 5 mm could be adopted as the design

CBR.


57/138

5.56

5.71

Mean

5.71 %Design CBR

5.565.445.695.0 mm

5.765.545.842.5 mm

321

CBR (%)

Penetration

Computation of Design CBR


58/138

1. Sieve Analysis

Significance of Test


59/138

Significance of Test

Each type of aggregate test

requires a specifiedaggregate size

(E.g. 10-12.5 mm for crushingtest)

Each bituminous mix typehas a recommendedaggregate gradation

(% passing 26.5 mm in 55-90

for GSB1) So aggregate is passed

through a set of sieves to getmaterial of various sizes

Sieves and Sieve shaker


60/138

Sieves and Sieve-shaker

Procedure


61/138

Procedure

Bring the sample to an air dry condition either by drying at

room temperature or in oven at a temperature of 100oC to110oC.Take the weight of the sample.

Clean all the sieves and sieve the sample successively onthe appropriate sieves starting with the largest.

Shake each sieve separately over a clean tray.

On completion of sieving note down the weight ofmaterial retained on each sieve.

Report the results as cumulative percentage by weight ofsample passing each of the sieves.

Observation Sheet


62/138

Observation Sheet

IS:2386 Part I; IS: 383

I.S. Sieve

designation

Weight of

sample

retained (gm)

weight retained

Percent of

(%)

Cumulativepercent of weight

retained (%)

Percentage

passing

(%)

63 mm

40 mm20 mm

12.5 mm

10 mm

4.75 mm


63/138

2. Aggregate Crushing Test

Significance


64/138

Significance

Aggregate crushing value provides a relative

measure of resistance to crushing under a graduallyapplied compressive load

Aggregates subjected to high stresses during rolling

and severe abrasion under traffic

Also in India very severe stresses come on

pavements due to rigid tyre rims of heavily loaded

animal drawn vehicles

Test Set-up


65/138

Test Set-up

Procedure


66/138

Procedure

Surface dry aggregates passing 12.5 mm and

retained on 10 mm selected

3.25 kg aggregate required for one test sample

Cylindrical measure filled with aggregates in 3 layers,tamping each layer 25 times

After leveling the aggregates at the top surface thetest sample is weighed

The cylinder is now placed on the base plate

Contd.


67/138

The cylinder with the test sample and plunger inposition is placed on compression machine

Load is applied at a rate of 4 tonnes per minute upto40 tonnes

The crushed aggregate is taken out, sieved through2.36 mm IS sieve and weighed to get materialpassing

Aggregate crushing value = W2*100/W1

W2= Weight of crushed material

W1=Total weight of sample

Load Application


68/138

Load Application

Sample being loaded

in the compression

machine at 4 T per

minute for 10 minutes

(upto 40 T)

Observation Sheet


69/138

Observation Sheet

Note: Value recorded up to first decimal place

Aggregate Crushing

Value= W1/W2*100

Wt. of AggregateSamplePassing 2.36 mmSieveAfter the Test= W2(gms)

Wt. of Aggregate SampleFilling in The Cylinder=W1(gms)

321AverageTest No.Observations

Specifications


70/138

Specifications

45% Max for

Other Surfaces

30% Max for

Surface Course

As per IRC:15

1970

And

IS: 2386:Part IV

Aggregate Crushing Value for

Cement Concrete PavementsSpecified By

Discussion


71/138

Discussion

Indirect measure of crushing strength

Low value indicate strong aggregates

Surface course need more strength than base course

Should not exceed 30% for cement concrete surface ,

and 45% for others


72/138

3. Aggregate Impact Test

Significance


73/138

Significance

This test assesses the suitability of aggregate as

regards the toughness for use in pavementconstruction

Road aggregates subjected to pounding action due

to traffic loads- so possibility of breaking

Should be tough enough- so proper aggregates to

be used

Suitability to be checked by laboratory tests

Test Set-up


74/138

Test Set up

Procedure


75/138

1. Aggregate passing through 12.5 mm IS sieve and retained on

10 mm sieve is filled in the cylindrical measure in 3 layers bytamping each layer by 25 blows. Determine the net weight of

aggregate in the measure(W1)

2. Sample is transferred from the measure to the cup of

aggregate impact testing machine and compacted by tamping

25 times

3. The hammer is raised to height of 38 cm above the upper

surface of the aggregates in the cup and is allowed to fall

freely on the specimen

Test In progress


76/138

Test In progress

Contd.


77/138

After subjecting the test specimen to 15blows, the crushed aggregate is sievedthrough IS 2.36 mm sieve

Weigh the fraction passing through IS 2.36mm sieve(w2)

Aggregate impact value = w2/w1*100

w2 = Weight of fines passing 2.36 mm

w1 = Weight of sample

Mean of the two values reported

Observation Sheet


78/138

Observation Sheet

Note: Value Recorded to the Nearest Whole Number

Aggregate Impact Value=

W2/W1*100

Wt. of Aggregate

Sample

Passing 2.36 mm Sieve

After the Test= W2

(gms)

Wt. of Aggregate Sample

Filling in The Cylinder=

W1(gms)

321 Avg

Test No.

Observations

Specifications


79/138

Specifications

30Bituminous Wearing Surfaces

IS: 2386: Part IV and IRC:15 1970; MORTH: 2001

30WBM Surface course

35

Bituminous Macadam, Base

course

45Cement Concrete Base course

50WBM Sub-base course

Aggregate Impact

Value, Max, %

Type of Pavement

Material/Layer


80/138

4. Los Angeles Abrasion Test


81/138

Test Set-up


82/138

p

Procedure


83/138

1. Aggregates dried in oven at 105 -110 C. to constantweight conforming to any one of the gradings

E.g. 1250 gm of 40-25 mm, 1250 gm of 25-20 mm,

1250 gm of 20-12.5 mm, 1250 gm of 12.5-10 mm,

with 12 steel balls

2. Aggregate weighing 5 kg or 10 kg is placed in cylinder

of the machine(W1gms)

3. Machine is rotated at 30-33 rpm for 500 revolutions

12. Machine is stopped and complete material is taken

out including dust

Grading Requirement


84/138

5000

2512-----500

05000---G

50002512-----NA5000500

0--F

50002512-------500

0250

02500E

5000256500

0---------D

5000258-250

02500-------C

50002511---250

0

250

0-----B

50002512---

125

0

125

0

125

01250---A

Wt.of

Charge,g

No.of

S

heres

4.7

5-

6.3-4.7

5

10-6.3

12.5-1

0

20-12.5

25-2

0

40-2

5

50-4

0

63-5

0

80-6

3

Abrasive

ChargeWt. in gms of each Sample in the Size Range, mm

Gradin

g

After 500 1000 revolutions


85/138

Contd.


86/138

6.Sieved through 1.7 mm sieve

7. Weight passing is determined by washing the

portion retained, oven drying and weighing (W2

gms)

8. Aggregate abrasion value is determined

A.A.V. = W2/W1*100

W2 = Weight of fines passing 1.7 mm

W1 = Weight of the sample

Specifications


87/138

p

60WBM Sub-base course

IS: 2386: Part IV; IRC:15 1970; IS: 383

30

Bituminous/Cement concrete

Wearing course

35

Bituminous Carpet, SD, Cement

Concrete surface course

40

WBM Surface course, BM binder

course

50WBM Base course with bit.

Surfacing, BM Base course

L. A. Abrasion

Value, Max, %Type of Pavement Layer

Discussion


88/138

Select a grading close to the project for testing

Simulate both abrasion and impact due to wheel loads

It determines the hardness of the stone


89/138

7. Shape Tests

Determination of:

a.Flakiness Index

b.Elongation Index

c.Angularity Number

Significance


90/138

g

Shape of crushed aggregates determined by the percentage of

flaky and elongated particles

Shape of gravel determined by its angularity number

Flaky and elongated aggregate particles tend to break under

heavy traffic loads

Rounded aggregates preferred in cement concrete pavements

as more workability at less water cement ratio

Angular shape preferred for granular courses/flexible pavement

layers due to better interlocking and hence more stability

Test Set-up


91/138

Length Gauge for Elongation Inde

Thickness Gauge for Flakiness Index


92/138

Flakiness Index Test in Progress


93/138

Flakiness Index Test in Progress

Flakiness


94/138

4.The amount of flaky material is weighed to an accuracy of

0.1 percent of the test sample

5. If W1,W2,W3,. are the total weights of each size ofaggregates taken and w1,w2,w3,.. are the weights ofmaterial passing the different thickness gauges then:

Flakiness Index

= (w1+w2+w3+.)*100

(W1+W2+W3+.)

= 100*w percent

W

Where,

W = Total wt of material taken in gms

w = Total wt of material passing in gms

Observation sheet (Flakiness Index)


95/138

Passing

through

I.S. Seive,

(mm)

Retained

on I.S.

Seive,

(mm)

63 50 W1= 23.9 w1=50 40 W2= 27 w2=

40 31.5 W3= 19.5 w3=

31.5 25 W4= 16.95 w4=

25 20 W5= 13.5 w5=

20 16 W6= 10.8 w6=

16 12.5 W7= 8.55 w7=

12.5 10 W8= 6.75 w8=

10 6.3 W9= 4.89 w9=

Total W= w=

Size of aggregateWt. Of the

fraction

consisting of at

least 200

pieces (gm)

Thickness

gauge size,

(0.6 times the

mean sieve)

(mm)

Weight of

aggregate in each

fraction passing

thickness gauge

(gms)

Elongation Index


96/138

Elongation Index

Elongation Index: The percentage by weight ofparticles whose greatest dimension is greater than one andfour fifth times (1.8 times) their mean dimension. Applicable

to sizes >=6.3 mm

1. The sample is sieved through sieve sizes, 50, 40, 25,

20, 16, 12.5, 10 and 6.3

2. Minimum 200 pieces of each fraction to be tested are

taken and weighed (W1 gm)

3. Separate the elongated

material by using the standard length gauge

Elongation Index Test in Progress


97/138

Elongation Index


98/138

4. The amount of elongated material is weighed to an accuracy of

0.1 percent of the test sample

5. If W1,W2,W3,. are the total weights of each size of

aggregates taken and w1,w2,w3,.. are the weights of material

retained on the different length gauge slots then:

Elongation Index

= (w1+w2+w3+.)*100

(W1+W2+W3+.)

= 100*w percent

W

Where,

W = Total wt of material taken in gms

w = Total wt of material retained in gms

Observation sheet (Elongation Index)


99/138

Passing

through

I.S.

Seive,

(mm)

Retainedon I.S.

Seive,

(mm)

50 40 W1= 81 w1=40 25 W2= 58 w2=

25 20 W3= 40.5 w3=

20 16 W4= 32.4 w4=

16 12.5 W5= 25.5 w5=

12.5 10 W6= 20.2 w6=10 6.3 W7= 14.7 w7=

Total W= w=

Size of aggregate

Wt. Of the

fractionconsisting of

at least 200

pieces (gm)

Length

gauge size,(1.8 times

the mean

sieve) (mm)

Weight of

aggregate in

each fraction

retained on

length gauge

(gms)

Specifications


100/138

15(do)Bit. Macadam, WBM base

& surfacing

course

IS: 2386, Part I; IRC: 14-48 ; MORTH: 2001

35Cement Concrete

25(do)Asphaltic concrete

Penetration macadam

Bit. Surface dressing

30(Combined FI and EI)Bituminous carpet

Limit of Flakiness Index

(%)

Type of pavement

construction

Angularity number


101/138

The angularity number measures the percent

voids in excess of 33 percent which is obtained inthe case of the most rounded gravel particles.Ranges from 0-11 (rounded gravel-crushedangular)

1. The cylinder is calibrated by determining theweight of water at 27oC required to fill it

2. Aggregate is sieved through 20, 16, 12.5, 10,

6.3 and 4.75 mm IS sieves3. About 10 kg of the predominant size should

be available

Test in Progress


102/138

Contd.


103/138

4. The sample of single-size aggregate is dried in an oven at

100o

to 110o

C for 24 hours and then cooled

5. The scoop is filled with aggregate which is allowed to slide

gently into the cylinder from the lowest possible height

6. The aggregate is filled in three layers, tamping each layer

evenly 100 times with a tamping rod

7. After the third layer is tamped, the aggregates are struck off

level with the help of tamping rod and surface finished

8. The aggregate with cylinder is now weighed to the nearest 5 g.

The mean weight of aggregate is found

Calculations and Observation Sheet


104/138

Angularity number = 67-100*WC*G

where, W = mean weight of aggregates in the cylinder,g

C = Weight of water required to fill the cylinder,g

G = Specific gravity of aggregate

Angularity Number = 67 - 100*W/C*G =

Mean weight of aggregate filling the cylinder, Wt =

Weight of aggregate filling the

cylinder to the nearest fivegrams, g

321Mean

Trial numberParticulars

Specific gravity of the aggregate = G =Weight of water filling the cylinder = C g =

Discussion


105/138

Elongated, flaky and angular materials decreases the workabilityof the mix, and not preferred in cement concrete

Angular aggregates are preferred in flexible pavement at WBM /WMM

Angularity number ranges from zero for perfectly roundedaggregate (rounded pebbles) to about 11 percent for freshlycrushed aggregates

But for DBM & BC mix design may be modified to incorporatehigh angularity number


106/138

Penetration test for Bitumen

Significance


107/138

The penetration test determine thehardness or softness of bitumen

The bitumen grade is specified in terms of

the penetration value

30/40 and 80/100 grade bitumen arecommonly used

In hot climates a lower penetration gradebitumen is preferred and vise versa

Significance


108/138

Consistency of bitumen varies with temperature, constituents,

refining process, etc.

Viscosity is an absolute property, but could not be determined

easily

Viscosity of cutback bitumen by indirect method (orifice

viscometer)

Too soft for penetration, too hard for orifice then perform floattest

Significance


109/138

Basic principle of penetration test:

measurement of penetration in units of 1/10th of a mmof a standard needle of 100 gm in a bitumen sample

kept at 25C for 5 seconds

Higher penetration implies softer grade

Purpose is classification

Figure

Penetrometere Water Bath


110/138

Penetrometere Water Bath

Weight

Dial

Needle

Mould

Temperature Controller

Procedure


111/138

Heat the bitumen to softening point +900 C

Pour the bitumen into the container at least 10 mm above the

expected penetration

Place all the sample containers to cool in atmospheric temperature

for 1 hour

Place the sample containers in temperature controlled water bath at

a temperature of 250 C 1o C for a period of 1 hour

Fill the transfer dish with water from the water bath to cover the

container completely


112/138

Continue. . . .


113/138

Take off the sample container from the water bath,

place in transfer dish and place under the middle ofpenetrometer

Adjust the needle to make a contact with surface of

the sample See the dial reading and release the needle exactly

for 5 seconds

Note the final reading

Difference between the initial and final readings is

taken as the penetration value in 1/10th of mm

(i) P i t t

Observation Sheet


114/138

Average Value =

Final

Initial

Mean

value

Test

3

Test

2

Test

1

Mean

value

Test

3

Test

2

Test

1

Sample No 2Sample No 1Penetro-

meter dial

readings

(v) Actual test temperature =

(iv) Period of cooling in water bath, minutes =

(iii) Room temperature =

(ii) Period of cooling in atmosphere, minutes =

(i) Pouring temperature =

IS Specifications


115/138

7%Above 225

5%80-225

4%0-80

RepeatabilityPenetration

Grade

175-22580-10060-7040-5030-4020-30PenetrationValue

A200 &

S200

A90 &

S90

A65 &

S65

A45 &

S45

A35 &

S35A25

Bitumen

Grade

Discussion


116/138

Test is highly influenced by the pouring temperature, size of

needle, weight of needle, test temperature, duration of release of

needle

IRC suggests 30/40, 60/70, 80/100 for BM

High penetration grade is desirable in colder regions

Penetration below 20 will result in cracking

For lower penetration, bonding is difficult, but once achieved will

remain for a long time


117/138

Ductility Test


118/138

Ductility Machine

Significance


119/138

The ductility of bitumen improves the physical

interlocking of the aggregate bitumen mixes

Under traffic loads the pavement layer is subjected to

repeated deformation. The binder material of loductility would crack and thus provide pervious

pavement surface

The test is believed to measure the adhesive property ofbitumen and its ability to stretch

Significance


120/138

Ductility and penetration go together, in general, but exception

can happen

Ductility is the distance in cm to which a standard briquette of

bitumen can be stretched before the thread breaks

Ductile materials is one which elongates when held in tension

Procedure


121/138

The bitumen sample is melted to temperature of 75oC to

100oC above the approx. softening point until it is fluid

It is strained through IS sieve 30, poured in mould

assembly and placed on a brass plate, after a solution of

glycerine or dextrine is applied over all surfaces of the

mould exposed to bitumen

Thirty to forty minutes after the sample is poured into

the moulds, the plate assembly along with the sample is

placed in water bath maintained at 27oC for 30 minutes


122/138

Briquette Moulds

Continue. . . .

The sample and mould assembly are removed


123/138

The sample and mould assembly are removed

from water bath and excess bitumen material is

cut off by leveling the surface using hot knife

After trimming the specimen, the mould assembly

containing sample is replaced in water bath

maintained at 27oC for 85 to 95 minutes

The slides of the mould are then removed and the

clips are carefully hooked on the machine withoutcausing any initial strain

The pointer is set to read zero


124/138

Ductilometer In Operation

Continue. . . .


125/138

The machine is started and the two clips are thus

pulled apart horizontally

While the test is in operation, it is checked whether

the sample is immersed in water up to a depth of at

least 10mm

The distance at which the bitumen thread breaks is

recorded (in cm) and reported as ductility value

Breaking of Thread


126/138

Observation sheet(i) Grade of bitumen =


127/138

(i) Grade of bitumen

(ii) Pouring temperature C =

(iii) Test temperature =(iv) Period of cooling (minutes) in Air =

In water bath before trimming =

In water bath after trimming =

Reproducibility

%

Repeatability %

Ductility (cm)

cbaMean Value

Briquette NumberTest Property

IS Specification


128/138

Note: S denotes sources other than Assam

petroleum

75S 45,S 65 & S 90

50S 35

Minimum

Ductility (cm)

Source of Paving Bitumen

& Penetration Grade

10%Reproducibility

5%

Repeatability

Discussion


129/138

Ductility of bitumen is affected by the pouring temperature,

briquette size, placement of briquette, test temperature, rate of

pulling

Ductility value ranges from 5-100. Low value implies cracking.

Some minimum ductility is needed for flexural strength

The lack of ductility does not necessarily indicate poor quality.


130/138

Softening Point

Significance


131/138

Bitumen does not melt, but change gradually from solid

to liquid

Softening point is the temperature at which the bitumen

attains particular degree of softening under specified

test conditions

Ring and ball apparatus is used for the test

Ring & Ball Test Set-up


132/138

Glass Beaker

Brass Rings

(In =15.9 Mm & Out =17.5mmSteel Balls = 9.5 mm (2.5g)

Metallic Support

Thermometer

Mechanical Stirrer

Temp Controlled

Heating Plate

Procedure Heat the bitumen to a temperature between 125oC to


133/138

150oC

Heat the rings at the same temperature on a hot plate

& place on glass plate coated with glycerin

Fill up the rings with bitumen

Cool for 30 minutes in air and level the surface with

a hot knife

Set the rings in the assembly and place in the bath

containing distilled water at 5oC and maintain that

temperature for 15 minutes


134/138

Observation table


135/138

(i) Grade of bitumen =

(ii) Approximate softening point =(iii) Liquid used in water bath(water/Glycerin) =

(iv) Period of air cooling (minutes) =

(v) Period of cooling in water bath(minutes) =

IS Specifications

ReproducibilityR t bilit ( C)S ft i P i t


136/138

42>80oC

2130oC- 80oC42


137/138

Test is affected by quality of liquid, weight of ball, rate of heating

etc

It gives an idea of the temperature at which the bituminous

material attains a certain viscosity

Bitumen with higher softening point is used in warmer places

Softening point is very critical for thick films like joint and crack

fillers, to ensure they will not flow

Other tests


138/138

Viscosity of bitumenCommon demo

Brook field viscometer

Marshall mix design

Theory + lab

Traffic studies:

highway material experiments

Documents

Transcript of highway material experiments