test method bit

8/2/2019 Test Method Bit

1/24

VKLR - QME74

BITUMEN & BITUMINOUS

MATERIALS.


2/24

VKLR - QME75

Bitumen:

Bitumen is a petroleum product obtained by the distillation of petroleum crude.

Tar:

Tar is obtained by the destructive distillation of coal or wood.

Both bitumen and tar have similar appearance, as both are black in color, both these

materials can be used for pavement works, but they have different characteristics.

The bitumen is brought to sufficient fluidity or viscosity before use in pavementconstruction by any one of the following three methods:

a) by heating, in the form of hot bitumen binder.

b) by dissolving in light oils, in the form of cutback bitumen.

c) by dispersing bitumen in water, in the form of bituminous emulsion.

The paving bitumen available in India is classified into two categories:

i) paving bitumen from Assam petroleum denoted as A-type and designated as A35, A45,

A55, A65, A90 & A200.

ii) paving bitumen from other sources denoted as S-type and designated as S35, S45, S55,S65, S90 & S200.

Cutback bitumen: is defined as the bitumen, the viscosity of which has been reduced by

a volatile diluents. For use in surface dressings, some types of bituminous macadam.Cutback bitumens are available in three types, namely (i) Rapid curing (RC), (ii) Medium

curing (MC) and (iii) Slow curing(SC).

Bitumen Emulsion: is a liquid product in which a substantial amount of bitumen issuspended in a finely divided condition in an aqueous medium and stabilized by means of

one or more suitable materials. The main advantages of emulsions are that (i) they can beused, without heating for preparing mixes, (ii) they are particularly useful for patch

repair works and can be used even when the surface is wet or it is raining. Three types of

emulsified bitumen can be prepared (i) Rapid Setting (RS)- is a setting emulsifiedbitumen used for penetration and surface treatment, (ii) Medium Setting (MS)- is used forplant mixes with coarse aggregate, (iii) Slow Setting (SS)- is used for fine aggregate

mixes.


3/24

VKLR - QME76

1. PENETRATION TEST

( IS : 1203 1978 )

INTRODUCTION:

Penetration test is the test on bitumen to grade the material in term of its hardness.

Object:

To determine the penetration of bitumen by penetration test.

Apparatus:

a) Container: A flat-bottomed cylindrical metallic container 55mm in diameter and35mm or 57mm in height.

b) Needle: A straight, highly polished hard steel needle.

c) Water bath: A water bath is maintained at 25 +/- 10C containing not less than 10 liters

of water, the sample is immersed to depth not less than 100mm from the top andsupported on a perforated shelf not less than 50mm from the bottom of the bath.

d) Penetrometer: Electrically operated automatic penetrometer / Manually operated

penetrometer. It is an apparatus, which allows the needle assembly of gross weight100gm to penetrate without appreciable friction for the desired duration of time 5 sec.

The dial is accurately calibrated to give penetration value in units of one tenth of an mm.

e) Transfer tray: A small tray, which can keep the container fully immersed in waterduring the test.

f) Stop Watch.

Procedure:

The bitumen is softened to a pouring consistency between 750C and 100

0C above the

approximate temperature at which bitumen softens. The sample material is thoroughlystirred to make it homogenous and free from air bubbles and water. The sample material

is then poured into the containers to a depth at least 15 mm more than the expected

penetration. The sample containers are cooled in atmosphere temperature not lower than130C for one hour. Then they are placed in temperature controlled water bath at a

temperature of 250C for a period of one hour.

The sample container is placed in the transfer tray with water from the water bath and

placed under the needle of the penetrometer. The weight of needle, shaft and additionalweight are checked. The total weight of this assembly should be 100gm.


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VKLR - QME77

Using the adjusting screw, the needle assembly is lowered and the tip of the needle is

made to just touch the top surface of the sample, the needle assembly is clamped in thisposition. The contact of the tip of the needle is checked using the mirror placed on the

rear of the needle. The initial reading of the penetrometer dial is either adjusted to zero orthe initial reading is taken before releasing the needle. The needle is released exactly for a

period of 5 secs. by pressing the knob and the final reading is taken on the dial. At leastthree measurements are made on this sample by testing at distance of not less than 10mm

apart. After each test the needle is disengaged and cleaned with benzene and carefullydried. The sample container is also transferred in the water bath before next testing is

done so as to maintain a constant temperature of 250C. The test is repeated with sample in

the other containers.

Results:

The difference between the initial and final penetration readings is taken as the

penetration value.

Bitumen

gradeA35 & S35 A45 & S45 A55 & S55 A65 & S65 A90 & S90 A200 & S200

Penetration

value30 to 40 40 to 50 50 to 60 60 to 70 80 to 100 175 to 225


5/24

VKLR - QME78

2.SPECIFIC GRAVITY TEST.

( IS : 1202 1978 )

Object:

To determine the specific gravity of the bitumen by specific gravity bottle.

Apparatus:

a) Pycnometer / specific gravity bottle 50 ml capacity.

b) Balance sensitivity 0.1mg.

Procedure:

The specific gravity bottle is cleaned, dried and weighed along with the stopper. It is

filled with fresh distilled water, stopper placed and the same is kept in water container forat least half an hour at temperature 27

0C +/- 1

0C. The bottle is then removed and cleaned

from outside. The specific gravity bottle containing distilled water is now weighed.

The bituminous material is heated to a pouring temperature and is poured in the above

empty bottle taking all the precautions that it is clean and dry before filling samplematerials. The material is filled up to the half taking care to prevent entry of air bubbles.

To permit an escape of air bubbles, the sample bottle is allowed to stand for half an hourat suitable temperature cooled to 27

0C and then weighed. The remaining space in the

specific gravity bottle is filled with distilled water at 270C, stopper placed and is placed in

water container at 270C. The bottle containing bituminous material and remaining water

is removed, cleaned from outside and is again weighed.

Calculations:The specific gravity of the bituminous material is calculated as follows:

Weight of bituminous material ( c a )

Specific gravity = =Weight of equal volume of water at 27

0C (b a) (d c)

Where a = weight of the specific gravity bottle

b = weight of the sp.gravity bottle filled with distilled water.

c = weight of the sp.gravity bottle about half filled with bitumen.d = weight of the sp.gravity bottle about half filled with bitumen andthe distilled water.

Limits: Specific gravity of Bitumen at 270C is Minimum 0.99.


6/24

VKLR - QME79

3.SOFTENING POIN TEST ( RING AND BALL TEST ).

( IS : 1205 1978 )

INTRODUCTION:

Bitumen does not suddenly change from solid to liquid state, but as the temperatureincreases, it gradually becomes softer until it flows readily. All semi-solid state bitumen

grades need sufficient fluidity before they are used for application with the aggregatemix. For this purpose bitumen is sometimes cutback with a solvent like kerosene. The

common procedure however is to liquefy the bitumen by heating. The softening point isthe temperature at which the substance attains particular degree of softening under

specified condition of test. For bitumen, it is usually determined by Ring and Ball test.

Object:

To determine the softening point of the bitumen by Ring and Ball apparatus.

Apparatus:

a) Ring and Ball apparatus It consists(i) Steel Balls 2 nos.each has a diameter of 9.5mm and weight is 2.5+/-0.05gm.

(ii) Brass Rings 2 nos. each 6.4mm depth, inside diameter at top 17.5mm, insidediameter at bottom 15.9mm and outside diameter 20.6mm and three equally spaced ball

guides.(iii) Support - The metallic support is used for placing pair of rings. The upper surface of

the rings is adjusted to be 50mm below the surface of water or liquid contained in thebath. A distance of 25mm between the bottom of the rings and top surface of the bottom

plate of support is provided. It has a housing for a suitable thermometer.

b) Thermometer 00C to 350

0C sensitivity 0.1

0C.

c) Bath and stirrer A heat resistant glass container of 85mm diameter and 120mm depthis used.

Procedure:

Sample material is heated to a temperature between 75 and 1000C above the approximate

softening point until it is completely fluid and is poured in heated rings placed on metal

plate. To avoid sticking of the bitumen to metal plate, coating is done to this with asolution of glycerin and dextrin. After cooling the rings in air for 30 minutes, the excessbitumen is trimmed and rings are placed in the support as mentioned in item(iii) above.

At this time the temperature of distilled water is kept at 50C. This temperature is

maintained for 15 minutes after which the balls are placed in position. The temperature of

water is raised at uniform rate of 50C per minute with a controlled heating unit, until the

bitumen softens and touches the bottom plate by sinking of balls. At least two

observations are made.


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VKLR - QME80

Results:

The temperature at the instant when each of the ball and sample touches the bottom plate

of support is recorded as softening value.

Limits:

Bitumen

gradeA35 & S35 A45 & S45 A55 & S55 A65 & S65 A90 & S90 A200 & S200

Softening

point50 to 65

0C 45 to 60

0C 45 to 60

0C 40 to 55

0C 35 to 50

0C 30 to 45

0C


8/24

VKLR - QME81

4.VISCOSITY TEST.

( IS : 1206 1978 )

INTRODUCTION:Viscosity is defined as inverse of fluidity. Viscosity thus defines the fluid property of

bituminous material. The degree of fluidity at the application temperature greatlyinfluences the ability of bituminous material to spread, penetrate into the voids and also

coat the aggregates and hence affects the strength characteristics of the resulting pavingmixes.

Object:

To determine the viscosity of bitumen by Tar Viscometer.

Apparatus:Tar Viscometer with 4mm and 10mm orifices The apparatus consists of main parts like

cup, valve, water bath, sleeves, stirrer, receiver and thermometers etc.

Procedure:The tar cup is properly leveled and water in the bath is heated to the temperature

specified for the test and is maintained throughout the test. Stirring is also continued. Thesample material is heated at the temperature 20

0C above the specified test temperature,

and the material is allowed to cool. During this the material is continuously, stirred.When material reaches slightly above test temperature, the same is poured in the tar cup,

until the leveling peg on the valve rod is just immersed. In the graduated receiver(cylinder), 25ml of mineral oil or one percent by weight solution of soft soap is poured.

The receiver is placed under the orifice. When the sample material reaches the specifiedtesting temperature within +/- 0.1

0C and is maintained for 5 minutes, the valve is opened.

The stopwatch is started, when cylinder records 25ml. The time is recorded for flow up toa mark of 75ml.(i.e., 50ml of test sample to flow through the orifice).

Results:

The time in seconds for 50ml of the test sample to flow through the orifice is defined asthe viscosity at a given test temperature.


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VKLR - QME82

Limits:Type of

material

Orifice size,

mmTest temp,

0C

Viscosity

range, sec.

A35 & S35 10mm 600C 90 - 100

A45 & S55 10mm 600C 80 - 90

A55 & S55 10mm 600

C 70 - 80A65 & S65 10mm 60

0C 60 - 70

A90 & S90 10mm 600C 50 - 60

A200 & S200 10mm 600C 40 - 50

Cutback -

RC,MC&SC -

Grade - 0

4mm 250C 25 - 75

Grade - 1 4mm 250C 50 - 150

Grade - 2 10mm 250C 10 - 20

Grade - 3 10mm 250C 25 - 75

Grade - 4 10mm 400C 14 - 45

Grade - 5 10mm 400

C 60 - 140 Viscosity conversion chart:

Known Required Viscosity

Viscosity

c.s. sec. sec. sec. sec. sec. sec.Vk

0Engler Redw. Redw. STV STV Saybol Saybolt

I II 10mm 4mm Univ. Furol.

Centi Stock Vk 1 0.132 4.10 0.41 0.0025 0.076 4.7 0.470Engler 7.58 1 31.10 3.11 0.019 0.576 35.63 3.563

secs.Redw I 0.244 0.0322 1 0.10 0.00061 0.0185 1.12 0.112secs.Redw II 2.44 0.322 10 1 0.0061 0.185 11.2 1.12

secs.STV10mm 400 52.8 1640 164 1 30.4 1880 188secs.STV4mm 13.2 1.74 54.1 5.41 0.033 1 62.04 6.024

secs.Saybolt.Un. 0.213 0.028 0.873 0.0873 0.00053 0.0162 1 0.10secs.Saybolt.Fu. 2.13 0.28 8.73 0.873 0.0053 0.162 10 1


10/24

VKLR - QME83

5. FLASH AND FIRE POINT TEST.

( IS : 1209 1978 )

INTRODUCTION:

Bituminous materials leave out volatiles at high temperatures depending upon their grade.These volatile catch fire causing a flash. This condition is very hazardous and it is

therefore essential to qualify this temperature for each bitumen grade.

Flash point: The flash point of a material is the lowest temperature at which the vapourof substance momentarily takes fire in the form of a flash under specified condition of

test.Fire point: The fire point is the lowest temperature at which the material gets ignited and

burns under specified condition of test.

Object:

To determine the flash and fire point of bitumen by Pensky-Martens closed tester.

Apparatus:a) Pensky-Martens closed tester consist of cup, lid, stirrer device, shutter, flame exposure

device.b) Thermometer ( 0 350

0C) sensitivity 0.1

0C.

Procedure:

The material is filled in the cup up to a filling mark. The lid is placed to close the cup in a

closed system. All accessories including thermometer of the specified range are suitablyfixed. The bitumen sample is then heated. The test flame is lit and adjusted in such a way

that the size of a bleed is of 4mm diameter. The heating is done at the rate of 50C to 6

0C

per minute. The stirring is done at a rate of approximately 60 revolutions per minute. The

test flame is applied at intervals depending upon the expected flash and fire points. Firstapplication is made at least 17

0C below the actual flash point and then at every 1

0C to

30C. The stirring is discontinued during the application of the test flame.

Results:The flash point is taken as the temperature read on the thermometer at the time of the

flame application that causes a bright flash in the interior of the cup in closed system. For

open cup it is the instance when flash appears first at any point on the surface of thematerial. The heating is continued until the volatiles ignite and the material continues toburn for 5 seconds. The temperature of the sample material when this occurs is recorded

as the fire point.Limits: The flash point for all grades of bitumen materials is 175

0C, minimum.


11/24

VKLR - QME84

6.DUCTILITY TEST.

( IS : 1208 1978 )

INTRODUCTION:

In the flexible pavement construction where bitumen binders are used, it is of significantimportance that the binders form ductile thin films around the aggregates. This serves as

a satisfactory binder in improving the physical interlocking of the aggregates.

Object:

To determine the ductility of the bituminous material.

Apparatus:

a) Ductility machine.

b) Briquette moulds.c) Knife.

Procedure:

The bitumen sample is melted to a temperature of 75 to 1000C above the approximate

softening point until it is fluid. It is strained through 90 micron sieve, poured in the mould

assembly and placed on a brass plate, after a solution of glycerin and dextrin is applied atall surfaces of the mould exposed to bitumen. After 30 to 40 minutes, the plate assembly

along with the sample is placed in water bath maintained at 270C for 30 minutes. The

sample and mould assembly are removed from water bath and leveling the surface using

hot knife cuts off excess bitumen material. After trimming the specimen, the mouldassembly-containing sample is replaced in water bath maintained at 270C for 85 to 95

minutes. The sides of the mould are now removed and the clips are carefully hooked onthe machine with out causing any initial strain.

The pointer is set to zero, the machine is started and the two clips are pulled apart

horizontally at a uniform speed of 50 +/- 2.5mm per minute. While the test is inoperation, it is checked whether the sample is immersed in water at depth of at least

10mm. The distance, at which the bitumen thread of each specimen breaks, is recorded(in cm) to report as ductility value.

Results:The distance stretched by the moving end of the specimen up to the point of breaking ofthread measured in centimeters is recorded as ductility value.

Limits: The minimum ductility value of A35 & S35 grade bitumen is 50 cm at 270C.

All other grades, the ductility value is 75 cm at 270C.


12/24

VKLR - QME85

7.LOSS ON HEATING OF BITUMINOUS MATERIALS.

( IS : 1205 1978 )

INTRODUCTION:

The loss in weight (exclusive of water) of bituminous materials when heated is called losson heating of bituminous materials.

Object:

To determine the loss on heating of bituminous materials.

Apparatus:

a) Oven heating capacity is minimum 1800C and interior dimensions min.330X330mm.

b) Aluminum Rotating shelf - the self shall be suspended by vertical shaft and centeredwith respect to the horizontal interior dimensions minimum diameter of 250mm, andshall be provided with a mechanical means of rotating it at the rate of 5 to 6 rpm.

c) Thermometer 0 to 3600C sensitivity 0.1

0C.

d) Containers- Metal or glass cylindrical containers shall have a flat bottom and diameter

55mm, 35mm depth minimum.

e) Balance sensitivity 0.01gm.

Procedure:

Heat the sample with care, stirring constantly to prevent local overheating, until thesample has become sufficiently fluid to pour. Place the sample in container and cool the

sample to room temperature and then weigh to the nearest 0.01gm. Bring the oven to atemperature of 163

0C and place the container in oven for period of 5 hr. Remove the

sample from the oven, cool to room temperature, and weigh to the nearest 0.01gm. Andcalculate the loss due to heating.

Limits: Loss on heating of all grades, except A200 & S200 of bitumen is maximum 1%

by mass. Loss on heating of grade A200 & S200 is maximum 2% by mass.


13/24

VKLR - QME86

8.STRIPPING VALUE OF AGGREGATES.

( IS : 6241 1959 )

INTRODUCTION:

Bitumen and tar adhere well to all normal types of aggregates provided they are dry andare not exceptionally dusty. Largely the viscosity of the binder controls the process of

binding. When the viscosity of the binder is high, coating of aggregates by the binder isslower. In the absence of water there is practically no adhesion problem in bituminous

road construction. Two problems are observed due to the presence of water. First, ifaggregate is wet and cool it is normally not possible to coat with a bituminous binder.

This problem can be dealt with by removing the water film on aggregate by drying, andby increasing the mixing temperature. Second problem is stripping of coated binder from

the aggregate due to the presence of water. This problem of stripping is experienced onlywith bituminous mixtures, which are permeable to water.

Object:

To determine the stripping value of aggregates by static immersion method.

Apparatus:

Thermostatically controlled water bath, beaker.

Procedure:

This method covers the procedure for determining the stripping value of aggregates by

static immersion method, when bitumen and tar binder are used. 200gm of dry and cleanaggregates passing 20mm IS sieve and retained on 12.5mm sieve are heated up to 1500C

when these are to be mixed with bitumen and the aggregates are heated up to 1000C when

these are to be mixed with tar. 5% by weight of bitumen / tar binder is heated to 1600C

(1100C in the case of tar binder). The aggregate and binder are mixed thoroughly till they

are completely coated and the mixture is transferred to a 500ml beaker and allowed to

cool at room temperature for about two hours. Distilled water is then added to immersethe coated aggregates. The beaker is covered and kept in a water bath maintained at 40

0C,

taking care that the level of water in the water bath is at least half the height of thebeaker. After 24 hours the beaker is taken out, cooled at room temperature and the extent

of stripping is estimated visually while the specimen is still under water.

The stripping value is the ratio of the uncovered area observed visually to the total area ofaggregates in each test, expressed as a percentage.

Limits: The maximum stripping value is 5%( i.e., minimum retained coating is 95%).


14/24

VKLR - QME87

9.BINDER CONTENT OF PAVING MIXTURES.

( SP : 11 1976 )

Object:

To determine the binder content in the mix by cold solvent extraction.Apparatus:

a) Centrifugal extraction machine electrically operated.

b) Balance 15 kg capacity sensitivity 0.1gm.c) Cold solvent Commercial grade of Benzene.

d) Filter paper Wat 60.e) Oven.

Procedure:

A representative sample about 1000gm is exactly weighed and placed in the bowl of the

extraction apparatus and covered with commercial grade of benzene. Sufficient time (notmore than 1 hour) is allowed for the solvent to disintegrate the sample before running thecentrifuge.

The filter paper of the extractor is dried, weighed and then fitted around the edge of the

bowl. The cover of the bowl is clamped tightly. A beaker placed under to collect theextract.

The machine is revolved slowly and then gradually increases the speed, maximum of

3600 rpm. This speed is maintained till the solvent ceases to flow from the drain. Themachine is allowed to stop and 200ml of benzene is added and the above procedure is

repeated. A number of 200ml solvent additions (not less than three) are used till theextract is clear and not darker than a light straw colour.

The filter paper removed from the bowl, dried in air then in oven to constant weight at

1150C and weighted the fine materials that might have passed through the filter paper are

collected back from the extract preferably by centrifuging. The material is washed and

dried to constant weight as before. The percentage of binder in the sample is calculated asbelow.

W1 ( W2 + W3 ) + W4

Percentage of binder = X 100

W1Where W1 = Weight of sample.W2 = Weight of the sample after extraction.

W3 = Weight of Fine material recovered from the extract.W4 = Increase in weight of the filter paper.


15/24

VKLR - QME88

10.TEST FOR CONTROL OF RATE OF SPREAD OF BINDER.

( SP : 11 1976 )

Object:

To determine the rate of spread of binder by tray test.

Apparatus:

a) 20cmX20cm and 3cm deep metal trays 5 nos.b) Balance 0.1gm sensitivity.

Procedure:

Light metal trays of about 20cmX20cm and 3cm deep previously weighed and numbered,

are placed at intervals along the road in the path of the binder distributor between the

wheel tracks. After the distributor has passed, the trays are removed and wrapped inweighed sheets of paper so that they can be handled stocked and weighed as soon asconvenient. The spacing and the number of trays can be varied to suit the circumstances

of the particular site, but at least five trays shall normally be used. The tray test gives ameasure of the variation in rate of spread along the road and a good approximation to the

average rate of0 spread.

Precautions:

The trays shall be weighed correct to first place of decimal in gram. The maximumlongitudinal distribution error shall be within 10% of the specification.

Transverse distribution by the machine can be checked by placing a number of trays to

collect the binder sprayer over each 5cm of the width of the spray bar. The variation intransverse distribution shall not be more than 20% from the man (not counting the

extreme 15cm at either side of sprayed area).


16/24

VKLR - QME89

11.TEST FOR RATE OF SPREAD OF GRIT IN SURFACE DRESSING.

( SP : 11 1976 )

Object:

To determine the rate of spread of grit by measuring the area covered by each lorry loadof known capacity.

Procedure:

Measuring the area covered by each lorry load of known capacity can check the rate of

spread of grit by gritters.

Removing the chippings from small areas of the road and weighing them can also checkthis. A small square metal frame is laid on the new dressing and all the chippings within

the enclosed area which is 10cm square are collected and washed in solvent to remove

the binder, weighed and the rate of spread is measured at points along the road atintervals of between 1 meter to 4 meters.

The transverse variation shall be less than +/- 20 percent of the mean.


17/24

VKLR - QME90

12.MARSHALL STABILITY TEST.

( ASTM D 1559 & MS-2)

INTRODUCTION:

Bruce Marshall, a former Bituminous Engineer with the Mississippi State HighwayDepartment, formulated the concepts of the Marshall method of designing paving

mixtures. The U.S.Army Crops of Engineers, through extensive research and correlationstudies, improved and added certain features to Marshalls test procedure, and ultimately

developed mix design criteria.

The original Marshall method is applicable only to hot-mix asphalt paving mixturescontaining aggregates with maximum sizes of 25mm or less.

This method covers the measurement of the resistance to plastic flow of cylindrical

specimens of bituminous paving mixture loaded on the lateral surface by means of the

Marshall apparatus.

Object:

To determine the stability, flow, voids, voids in mineral aggregates, voids filled with

asphalt and density of the asphalt mixture by Marshall stability test.

Apparatus:

a) Specimen Mould Assembly Mould cylinders 101.6mm(4 in.) in diameter by75mm(3 in.) in height, base plates, and extension collars.

b) Specimen Extractor Steel disk with a diameter 100mm, and 12.7mm thick for

extracting the compacting specimen from the specimen mould with the use of the mouldcollar. A suitable bar is required to transfer the load from the proving ring adapter to the

extension collar while extracting the specimen.

c) Compaction Hammer The compaction hammer shall have a flat, circular tampingface and a 4.5kg(10 lb) sliding weight with a free fall of 457mm (18 in.). Two

compaction hammers are recommended.

d) Compaction Pedestal The compaction pedestal shall consist of

200X200X460mm(8X8X18 in.) wooden post capped with a 305X305X25mm(12X12X1in.) steel plate. The pedestal should be installed on concrete slab so that the post is plumband the cap is level. Mould holder provided consisting of spring tension device designed

to hold compaction mould centered in place on compaction pedestal.

e) Breaking Head It consists of upper and lower cylindrical segments or test headshaving an inside radius of curvature of 50 mm. The lower segment is mounted on a base

having two vertical guide rods, which facilitate insertion in the holes of upper test head.


18/24

VKLR - QME91

f) Loading Machine The loading machine is provided with a gear system to lift the

base in upward direction./ on the upper end of the machine, a calibrated proving ring of 5tonne capacity is fixed. In between the base and the proving ring, the specimen contained

in test head is placed. The loading machine produces a movement at the rate of 50mm perminute. Machine is capable of reversing its movement downward also.

g) Flow meter One dial gauge fixed to the guide rods of a testing machine can serve

the purpose. Least count of 0.25mm(0.01 in.) is adequate.

h) Oven or hot plates

i) Mixing apparatus.

j) Thermostatically control water bath.

k) Thermometers of range 0 3600C with 1

0C sensitivity.

Procedure:

In the Marshall method each compacted test specimen is subjected to the following testsand analysis in the order listed below:

i) Bulk density determination

ii) Stability and flow test

iii) Density and voids analysis

At least three samples are prepared for each binder content.

Preparation of test specimens:

The coarse aggregates, fine aggregates and the filler material should be proportioned and

mixed in such a way that final mix after blending has the gradation with in the specifiedrange.

The aggregates and filler are mixed together in the desired proportion as per the design

requirements and fulfilling the specified gradation. The required quantity of the mix is

taken so as to produce a compacted bituminous mix specimen of thickness 63.5mm,approximately.

Preparation of Mixtures: Weigh into separate pans for each test specimen the amount ofeach size fraction required to produce a batch that will result in a compacted specimen

63.5 +/- 1.27mm(2.5 +/-0.05 in.) in height. This will normally be about 1200gm(2.7 lb.).It is generally to prepare a trial specimen prior to preparing the aggregate batches. If the


19/24

VKLR - QME92

trial specimen height falls outside the limits, the amount of aggregate used for the

specimen may be adjusted using:

63.5 (mass of aggregate used)Adjusted mass of aggregate =

Specimen height (mm) obtained

Take the sample as mentioned above, and heated to a temperature of 1750

to 1900C. The

compaction mould assembly and hammer are cleaned and kept pre-heated to atemperature of 100

0C to 145

0C. The bitumen is heated to temperature of 121

0to 138

0C

and the required quantity of first trial percentage of bitumen (say, 3.5% by weight ofmineral aggregates) is added to the heated aggregate and thoroughly mixed using a

mechanical mixer or by hand mixing with trowel. The mixing temperature may be 1530

to160

0C. The mix is placed in a mould and compacted by hammer, with 75 blows on either

side (for light compaction it is 50 blows). The compaction temperature may be 1380

to

149

0

C. The compacted specimen should have a thickness of 63.5 +/- 3.0mm. Threespecimens should be prepared at each trial bitumen content, which may be varied at 0.5percent increments up to about 7.5 or 8.0 percent.

Marshall Stability and Flow values: The specimens to be tested are kept immersed

under water in a thermostatically controlled water bath maintained at 600

+/- 10C for 30 to

40 minutes. The specimen are taken out one by one, placed in the Marshall test head and

the Marshall Stability value (maximum load carried in kg. before failure) and the flowvalue (the deformation the specimen undergoes during loading up to the maximum load

in 0.25mm units) are noted. The corrected Marshall stability value of each specimen isdetermined by applying the appropriate correction factor.

The following tests are determined first, to find out the density, voids, VMA and VFB.

Tests:

The specific gravity and apparent specific gravity values of the different aggregates, filler

and bitumen used are determined first.

i) Bulk specific gravity of aggregate Gsb is given by:

P1 + P2 +. + Pn

Gsb = P1/G1 + P2/G2 +. + Pn/Gn

Where, Gsb = Bulk specific gravity for the total aggregate.P1, P2, Pn = Individual percentages by weight of aggregate.

G1, G2, Gn = Individual bulk specific gravities of aggregate.


20/24

VKLR - QME93

ii) Effective specific gravity of aggregate Gse is given by:

100 - Pb

Gse =Pmm/Gmm Pb/Gb

Where, Gse = Effective specific gravity of aggregate, constant for all at 5% bitumen

content.Gmm = Maximum specific gravity of paving mixture (no air voids), determine

by Vacuum pump test (ASTM D 2041).Pb = Bitumen content, percent by total weight of mixture.

Gb = Specific gravity of Bitumen.

iii) Maximum specific gravity of mixture Gmm is given by:

100

Gmm = Ps/Gse + Pb/Gb

Where, Gmm = Maximum specific gravity of paving mixture (no air voids)

Ps = Aggregate content, percent by total weight of mixturePb = Bitumen content, percent by total weight of mixture

Gse = Effective specific gravity of aggregateGb = Specific gravity of bitumen

iv) Bitumen absorption Pba is given by:

Gse - GsbPba = 100 Gb

Gse Gsb

Where, Pba = Absorbed bitumen, percent by weight of aggregateGse = Effective specific gravity of aggregate

Gsb = Bulk specific gravity of aggregateGb = Specific gravity of bitumen

v) Effective bitumen content of a paving mixture Pbe is given by:

Pba

Pbe = Pb - Ps100


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VKLR - QME94

vi) Voids in mineral aggregate in compacted paving mixture VMA is given by:

Gmb Ps

VMA = 100 -Gsb

Where, VMA = Voids in mineral aggregate, percent of bulk volumeGsb = Bulk specific gravity of total aggregate

Gmb = Bulk specific gravity of compacted mixturePs = Aggregate content, percent by total weight of mixture

vii) Air voids in compacted mixture Va is given by:

Gmm - Gmb

Va = 100 X

Gmm

Where, Va = Air voids in compacted mixture, percent of total volume

Gmm = Maximum specific gravity of paving mixtureGmb = Bulk specific gravity of compacted mixture

viii) Voids filled with bitumen in compacted mixture VFB is given by:

100(VMA Va)

VFB =VMA

Where, VFB = Voids filled with bitumen, percent of VMA

VMA = Voids in mineral aggregate, percent of bulk volumeVa = Air voids in compacted mixture, percent of total volume

Determination of Optimum Bitumen Content:

Six graphs are plotted with values of bitumen content against the values of:

a) Density Gmb g/cc.

b) Marshall Stability, S kg.

c) Voids in total mix, Va %.d) Flow value, F (0.25mm units).e) Voids filled with bitumen, VFB %.

f) Voids in mineral aggregate, VMA %.

Let the bitumen contents corresponding to maximum density be B1, corresponding tomaximum stability be B2 and that corresponding to the specified voids content Va (4.0%

in the case of dense AC mix) be B3. Then the Optimum Bitumen Content is given by:


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VKLR - QME95

Optimum Bitumen Content (OBC) = (B1 + B2 + B3)/3

The values of flow and VFB are found from the graphs, corresponding to bitumen

content OBC. All the design values of Marshall stability, flow, voids and VFB arechecked at the Optimum Bitumen Content, with the specified design requirements of the

mix.

Design Requirements of the mix:

i) Marshall Stability value, kg = 820 kg.(min.)ii) Flow value, 0.25mm units = 8 16

iii) Voids in total mix, Va % = 3 5 %iv) Voids in mineral agg.(VMA), % = 10 12 %(min.)

v) Voids filled with bitumen(VFB) %= 65 75 %

The highest possible Marshall stability values in the mix should be aimed at consistent

with the other four requirements mentioned above. In case the mix designed does notfulfill any one or more of the design requirements, the gradation of the aggregates orfiller content or bitumen content or combination of these are altered and the design tests

are repeated till all the requirements are simultaneously fulfilled.

Job Mix Formula:

The proportions in which the different aggregates, filler and bitumen are to be mixed arespecified by weight or by volume for implementation during construction.

Caution: Mixes with high Marshall stability values and very low Flow values are not

desirable as the pavements of such mixes may be brittle and are likely to crack underheavy traffic.

Correction Factors

Volume of

Specimen in cc

Approximate

Thickness of

S ecimen in mm

Correction Factors

457 - 470 57.1 1.19

471 - 482 58.7 1.14

483 - 495 60.3 1.09

496 - 508 61.9 1.04

509 - 522 63.5 1.00523 - 535 65.1 0.96

536 - 546 66.7 0.93

547 - 559 68.3 0.89

560 - 573 69.9 0.86


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VKLR - QME96

Swell test:

Apparatus:

a) Moulds with internal diameter 101.6mm(4 in.) and length 127mm(5 in.)b) Perforated, 98.4mm diameter x 3.2mm thick with adjustable stem, for swell

measurement.c) Dial gauge, mounted on tripod, with reading accuracy to 0.025mm.

d) Aluminum pans, 190mm diameter x 64mm deep.

Procedure:Allow compacted swell test specimen to stand at room temperature for at least one hour.

Place the mould and specimen in 190mm diameter x 64mm deep aluminum pan. Placethe perforated disk on specimen, position the tripod with dial gauge on mould, and set the

adjustable stem to give a reading of 2.54mm on the dial gauge. Introduce 500ml of waterinto the mould on top of the specimen and the measure distance from the top of the

mould to the water surface with the graduated scale. After 24 hours, read the dial gauge

to the nearest 0.025mm and record the change as swell. Also, measure the distance fromthe top of the mould to the water surface with the graduated scale and record the changeas permeability or the amount of water in ml that percolates into and/or through the test

specimen.

Note:

i) Water Sensitivity: The loss of stability on immersion in water at 600C. The allowable

limit is minimum 75% retained strength.

ii) Marshall Quotient (Stiffness): is the ratio of stability and flow.

Allowable limit for base course = 350for wearing surfaces = 400.


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VKLR - QME97

Marshall Curves:

Bitumen(%) vs Stability(kg) Bitumen(%) vs Density (g/cc)

1500

1200

900

600

300

3.5 4 4.5 5 5.5 6

2.5

2.4

2.3

3.5 4 4.5 5 5.5 6

Bitumen(%) vs Flow(mm) Bitumen (%) vs Voids(%)

10

8

6

4

2

3.5 4 4.5 5 5.5 6

10

8

6

4

2

3.5 4 4.5 5 5.5 6

Bitumen(%) vs VFB(%) Bitumen(%) vs VMA(%)

80

70

60

50

40

3.5 4 4.5 5 5.5 6

20

18

16

14

12

3.5 4 4.5 5 5.5 6

test method bit

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