transportation lab manual
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CE328 Highway Materials Testing Experiments
ByDr. Tom. V. Mathew
IIT Bombay
List of Tests1. Aggregate crushing test 2. Aggregate impact test3. Abrasion Test (L.A. abrasion test) 4. Shape test (FI, EI, Angularity No.)5. Penetration Test6. Ductility Test7. Softening Point8. Marshall Stability Test9. Bitumen Extraction Test10.Traffic studies: Volume study
Requirements of Pavements
Types Flexible Pavement Rigid Pavement
Structural Requirements to withstand the design factors to serve during the design life / minimum
service life
Functional Requirements considering pavement deterioration considering road – user requirement
Flexible Pavements
Loading in FP
Overview
Pavement materials
Soil (sub-grade, embankment)
Aggregates (coarse, fine)
Binders (Bitumen, cement)
Aggregate
Aggregate is the major component of allmaterials used in road construction
It is used in granular bases and sub base,bituminous courses and in cement concretepavements
Desirable properties of Aggregate
Strength:The aggregate should be sufficiently strong to withstand 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
Durability: The aggregate used in pavement should resistance to disintegrationdue to the action of weather
Shape of aggregate: Should not be Flakyand elongated
Adhesion with Bitumen: Should have goodaffinity to bitumen
Desirable properties of Aggregate
Soil
Soil is all unindurated mineral material lying above rock strata including air, water, and organic matter
It is non-homogeneous and porous
Properties greatly influenced by moisture, density and compaction
A number of pavement failure is attributed to soil failures
Properties of soil
Shape of soil particles (bulky, flaky)
Particle size classification (clay, silt, sand, gravel)
Grain size distribution (sedimentation analysis for <75m)
Porosity and void ratio
Soil density (dry and wet density)
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)
Petroleum distillation Flow Chart
Desirable Properties of Bitumen
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 viscosity characteristics
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
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 continuedpresence off water
Desirable Properties of Bitumen
Quality Control Tests: Soil
1. Gradation2. Atterberg Limits and indices (LL, PL,PI, SL)3. Laboratory Compaction (MDD and OMC)4. Field density test 5. CBR Test6. Plate bearing test
Quality control tests: Aggregate
1. Sieve analysis2. Aggregate crushing test3. Aggregate impact test4. 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
1. Penetration2. Ductility3. Softening point4. Specific gravity5. Loss on heating6. Flash & Fire point7. Viscosity 8. Solubility
Quality control tests: Bitumen
California bearing ratio (CBR)
A simple test that compares the bearing capacity 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
CBR
CBR value is the measure of resistance of material 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.
Basic TestThis consists of causing a plunger of 50 mm
diameter to penetrate a soil sample at the rate of 1.25 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 are recorded.
This load corresponding to 2.5 mm or 5 mm penetration is expressed as a percentage of standard load sustained by the crushed aggregates at the same penetration to obtain CBR value.
Definition of CBR
California bearing ratio is defined as the ratio (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.
Standard Load values on Crushed Stones for Different Penetration Values
183360012.5
162318010.0
13426307.5
10520555.0
7013702.5
Unit StandardLoad, kg/cm2
StandardLoad, kg
Penetration,mm
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
Loading MachineWith a capacity of at
least 5000 kg and equipped with a movable head or base that travels at an uniform rate of 1.25 mm/min.
Cylindrical MouldCylindrical mould with
inside 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.
Compaction RammerWeight 2.6 kg with a
drop of 310 mm (or) Weight 4.89 kg a
drop 450 mm.
Adjustable stem, perforated plate, tripod and dial gauge
Preparation of Test Specimen
Prepare the remoulded specimen at Proctor’s maximum dry density or any other density at which C.B.R is required. Maintain the specimen at optimum moisture content or the field moisture as required. The material used should pass 20 mm I.S. sieve. Prepare the specimen either by dynamic compaction or by static compaction.
Dynamic Compaction
Take about 4.5 to 5.5 kg of soil and mix thoroughly with the required water.
Just before making the compacted mould of soil, take representative 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
Compact the soil in the mould using either light compaction or heavy compaction. For light compaction, compact the soil in 3 equal layers, each layer being given 55 blows by the 2.6 kg rammer. For heavy compaction compact the soil in 5 layers, by giving 56 blows to each layer by the 4.89 kg rammer.
Dynamic Compaction
Remove the collar and trim the specimen smooth and flush with the mould.Remove the base plate and the displacer disc,
weigh the mould with compacted soil, and determine the wet unit weight. Place a filter paper on the base plate, invert the
specimen (5 cm gap is on the top) and attach the base plate so that the soil is in contact with the filter paper on the base.
Penetration Test Place the mould assembly with the surcharge weights on the
penetration test machine. Seat the penetration piston at the center of the specimen with
the smallest possible load, but in no case in excess of 4 kg so that full contact of the piston on the sample is established.
Set the stress and strain dial gauge to read zero. Apply the load on 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 less than 12.5 mm.
Detach the mould from the loading equipment. Take about 20 to 50 g of soil from the top 3 cm layer and determine the moisture content.
757269585038
ProvingRing
Reading(div)
49.9533.3018.5011.103.70
0
Load onPlunger
12.5107.5543
Penetration(mm)
138.75133.20127.65107.3092.5070.30
Load onPlunger
272.5182101.56120.500
ProvingRing
Reading(div)
Penetration(mm)
Data from a Typical CBR Test for Sample No.1
0
20
40
60
80
100
120
140
160
0 2.5 5 7.5 10 12.5
Penetration
Load
Load Vs Penetration Curve forSample No.1
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 the sample might not be horizontal
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 Sample No.1
2.5 5
1370
2055
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 penetrationCBR of Specimen at 5 mm penetration =
(117/2055)*100 = 5.69 %
Variation in CBR Values
At least three samples should be tested on each 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 casesWhere variation with in CBR values is more
than the permissible maximum variation the design CBR value should be the average of six samples and not three
Permissible Variation in CBR Value
± 531 and above
± 311-30
± 25-10
± 15
Maximum variationin CBR value
CBR (per cent)
Design CBRThe average CBR values corresponding to 2.5 mm
and 5 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 the average 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 at 2.5 mm, CBR at 5 mm could be adopted as the design CBR.
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
1. Sieve Analysis
Significance of Test Each type of aggregate test
requires a specified aggregate size
(E.g. 10-12.5 mm for crushing test)
Each bituminous mix type has a recommended aggregate gradation
(% passing 26.5 mm in 55-90 for GSB1)
So aggregate is passed through a set of sieves to get material of various sizes
Sieves and Sieve-shaker
Procedure
Bring the sample to an air dry condition either by drying at room temperature or in oven at a temperature of 100oC to 110oC.Take the weight of the sample.
Clean all the sieves and sieve the sample successively on the appropriate sieves starting with the largest.
Shake each sieve separately over a clean tray.
On completion of sieving note down the weight of material retained on each sieve.
Report the results as cumulative percentage by weight of sample passing each of the sieves.
Observation Sheet
IS:2386 Part I; IS: 383
I.S. Sieve designation
Weight of sample
retained (gm)weight retained
Percent of
(%)
Cumulative percent of weight
retained (%)
Percentage passing
(%)63 mm40 mm20 mm
12.5 mm10 mm
4.75 mm
Observation Sheet
IS SeiveDesignation
(mm)
Weight of sampleretained
(gm)
Weightretained
(%)
Cumulativeweight
retained(%)
Passing (%)
63 100 6.25 6.25 93.7540 200 12.5 18.75 81.2520 400 25 43.75 56.25
12.5 400 25 68.75 31.2510 300 18.75 87.5 12.5
4.75 200 12.5 100 01600 100
Gradation chart
0
20
40
60
80
100
120
4.75 10 12.5 20 40 63 63
Gradation
1. Aggregate Crushing Test
Significance
Aggregate crushing value provides a relative measure of resistance to crushing under a gradually applied 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
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 the test sample is weighed
The cylinder is now placed on the base plate
Contd….
The cylinder with the test sample and plunger in position is placed on compression machine
Load is applied at a rate of 4 tonnes per minute upto 40 tonnes
The crushed aggregate is taken out, sieved through 2.36 mm IS sieve and weighed to get material passing
Aggregate crushing value = W2*100/W1W2= Weight of crushed materialW1=Total weight of sample
Load Application
Sample being loaded in the compression machine at 4 T per minute for 10 minutes (upto 40 T)
Observation Sheet
Note: Value recorded up to first decimal place
Aggregate Crushing Value= W1/W2*100
Wt. of Aggregate SamplePassing 2.36 mm SieveAfter the Test= W2(gms)
Wt. of Aggregate SampleFilling in The Cylinder=W1(gms)
321Average
Test No.Observations
Observation Sheet
Observations Test No. Average1 2 3
Wt. of Aggregate SampleFilling in The Cylinder=W1 (gms)
362 354 343
Wt. of Aggregate SamplePassing 2.36 mm SieveAfter the Test= W2 (gms) 116 102 84
Aggregate Crushing Value =
W1 / W2 x 10032% 28.8 % 24.5 % 28.5 %
Note: Value recorded up to first decimal place
Specifications
45 %Max for
Other Surfaces
30 %Max for Surface
Course
As per IRC:15 1970
AndIS: 2386:Part IV
Aggregate Crushing Value for Cement Concrete PavementsSpecified By
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
2. Aggregate Impact Test
Significance This test assesses the suitability of aggregate as
regards the toughness for use in pavement construction
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
Procedure
1. Aggregate passing through 12.5 mm IS sieve and retained on
10 mm sieve is filled in the cylindrical measure in 3 layers by
tamping 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
Contd….
After subjecting the test specimen to 15blows, the crushed aggregate is sieved through IS 2.36 mm sieve
Weigh the fraction passing through IS 2.36 mm sieve(W2)
Aggregate impact value = W2 / W1 x100
w2 = Weight of fines passing 2.36 mmw1 = Weight of sample
Mean of the two values reported
Observation Sheet
Note: Value Recorded to the Nearest Whole Number
Aggregate Impact Value=W2/W1*100
Wt. of Aggregate SamplePassing 2.36 mm SieveAfter the Test= W2(gms)
Wt. of Aggregate SampleFilling in The Cylinder=W1(gms)
321Avg
Test No.Observations
Observation SheetObservations
Test No.Avg
1 2 3Wt. of Aggregate SampleFilling in The Cylinder=W1 (gms)
319 323
Wt. of Aggregate SamplePassing 2.36 mm SieveAfter the Test= W2 (gms)
65 68
Aggregate Impact Value=
W2 / W1 x10020.37 21.05 21
Note: Value Recorded to the Nearest Whole Number
Specifications
30Bituminous Wearing SurfacesIS: 2386: Part IV and IRC:15 1970; MORTH: 2001
30WBM Surface course35
Bituminous Macadam, Basecourse
45Cement Concrete Base course
50WBM Sub-base course
Aggregate Impact Value, Max, %Type of Pavement Material/Layer
3. Los Angeles Abrasion Test
Significance It is resistance to wear or hardness of
aggregates
Road aggregates at the top subjected to wearing action
Under traffic loads abrasion/attrition action within the layers as well
To determine suitability, tests have to be carried out
Test Set-up
Procedure1. Aggregates dried in oven at 105 -110 ° C. to constant
weight 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 ( W1 gms)
3. Machine is rotated at 30-33 rpm for 500 revolutions
4. Machine is stopped and complete material is taken out including dust
Grading Requirement
5000±2512-----50005000---G
5000±2512-----NA50005000--F
5000±2512-------500025002500E
5000±2565000---------D
5000±258-25002500-------C
5000±2511---25002500-----B
5000±2512---1250125012501250---A
Wt. of
Charge, g
No. of
Spheres
4.75-2.36
6.3-4.75
10-6.3
12.5-10
20-12.5
25-20
40-25
50-40
63-50
80-63
AbrasiveCharge
Wt. in gms of each Sample in the Size Range, mmGrading
After 500 – 1000 revolutions
Contd….
6. Sieved through 1.7 mm sieve
7. Weight passing is determined by washing the portion retained, oven drying and weighing (W2gms)
8. Aggregate abrasion value is determinedLAAV = W2 / W1 x100
W2 = Weight of fines passing 1.7 mmW1 = Weight of the sample
Specifications
60WBM Sub-base course
IS: 2386: Part IV; IRC:15 1970; IS: 383 30
Bituminous/Cement concrete Wearing course
35Bituminous Carpet, SD, Cement Concrete surface course
40WBM Surface course, BM binder course
50WBM Base course with bit. Surfacing, BM Base course
L. A. Abrasion Value, Max, %Type of Pavement Layer
Discussion
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
4. Shape Tests
Determination of:
a.Flakiness Indexb.Elongation Indexc. Angularity Number
Significance 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
Length Gauge for Elongation Index
Thickness Gauge for Flakiness Index
Procedure (Flakiness)
(a). Flakiness Index: The flakiness index of aggregates is the
percentage by weight of particles whose least dimension is less than
three-fifths (0.6) of their mean dimension. Applicable to sizes>= 6.3
mm
1.The sample is sieved through IS sieve sizes 63, 50, 40, 31.5, 25,
20, 16, 12.5, 10 and 6.3 mm
2. Minimum 200 pieces of each fraction to be tested are taken and
weighed (W1 gm)
3. Separate the flaky material by using the standard thickness gauge
Flakiness Index Test in Progress
Flakiness
The amount of flaky material is weighed to an accuracy of 0.1 percent of the test sample
If W1, W2, …, Wi are the total weights of each size of aggregates taken
If w1, w2, …, wi are the weights of material passing the different thickness gauges then:
%100%100....)(....)(
21
21
ii
ii
W
w
WWwwFI
Observation sheet (Flakiness Index)
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 aggregate Wt. 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 IndexElongation Index: The percentage by weight of particles whose greatest dimension is greater than one and four 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
Elongation Index
The amount of elongated material is weighed to an accuracy of 0.1 percent of the test sample
If W1, W2, …, Wi are the total weights of each size of aggregates taken
If w1, w2, …, wi are the weights of material retained on different thickness gauges then:
%100%100....)(....)(
21
21
ii
ii
W
w
WWwwEI
Observation sheet (Elongation Index)
Passing through
I.S. Seive, (mm)
Retained on 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 aggregateWt. Of the
fraction consisting 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
15(do)Bit. Macadam, WBM base & surfacing course
IS: 2386, Part I; IRC: 14-48 ; MORTH: 2001
35Cement Concrete
25(do)Asphaltic concretePenetration macadamBit. Surface dressing
30(Combined FI and EI)Bituminous carpet
Limit of Flakiness Index(%)Type of pavement construction
Angularity number
The angularity number measures the percent voids in excess of 33 percent which is obtained in the case of the most rounded gravel particles.
Range: 0-11 (rounded gravel-crushed angular)
1. The cylinder is calibrated by determining the weight 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 sieves
3. About 10 kg of the predominant size should be available
Test in Progress
Contd….
4. The sample of single-size aggregate is dried in an oven at 100o
to 110oC 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 SheetAngularity number AN = 67 - W x 100
G x Cwhere, W = mean weight of aggregates in the cylinder,g
C = Weight of water required to fill the cylinder,gG = Specific gravity of aggregate (2.71)
Weight of water filling the cylinder = C g = Specific gravity of the aggregate = G =
ParticularsTrial number
Mean1 2 3
Weight of aggregate filling thecylinder to the nearest five grams, g 4185 4195 4190Mean weight of aggregate filling the cylinder, Wt =2870Angularity Number = 67 – { (4190/2.71x100)/C } = 13
Discussion
Elongated, flaky and angular materials decreases the workability of 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 rounded aggregate (rounded pebbles) to about 11 percent for freshly crushed aggregates
But for DBM & BC mix design may be modified to incorporate high angularity number
5. Penetration test
Significance
The penetration test determine the hardness or softness of bitumen
The bitumen grade is specified in terms of the penetration value
30/40 and 80/100 grade bitumen are commonly used
In hot climates a lower penetration grade bitumen is preferred and vise versa
Significance
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 float test
Significance
Basic principle of penetration test:measurement of penetration in units of 1/10th of a mm of a standard needle of 100 gm in a bitumen sample kept at 25°C for 5 seconds
Higher penetration implies softer grade
Purpose is classification
FigurePenetrometere Water Bath
Weight
Dial
NeedleMould
Temperature Controller
Procedure 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
Continue. . . .
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
Penetro-meter dial readings
Sample No 1 Sample No 2
Test 1
Test 2
Test 3
Mean value
Test 1
Test 2
Test 3
Mean value
Initial 0 0 0
Final 85 85 75
Average Value = 82 (Grade is 80/100)
(i) Pouring temperature = 100 oC
(ii) Period of cooling in atmosphere, minutes = 60 mts(iii) Room temperature = 27 oC
(iv) Period of cooling in water bath, minutes = 60 mts
(v) Actual test temperature = 25 oC
Observation Sheet
IS Specifications
7%Above 225
5%80-225
4%0-80
RepeatabilityPenetration Grade
175-22580-10060-7040-5030-4020-30Penetration Value
A200 & S200
A90 &S90
A65 &S65
A45 & S45
A35 &S35A25Bitumen
Grade
Discussion
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
6. Ductility Test
Ductility Machine
Significance
The ductility of bitumen improves the physicalinterlocking of the aggregate bitumen mixes
Under traffic loads the pavement layer is subjected torepeated deformation. The binder material of lowductility would crack and thus provide perviouspavement surface
The test is believed to measure the adhesive property ofbitumen and its ability to stretch
Significance
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 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
Briquette Moulds
Continue. . . .
The sample and mould assembly are removedfrom water bath and excess bitumen material is cutoff 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 without
causing any initial strain
The pointer is set to read zero
Ductilometer In Operation
Continue. . . .
The machine is started and the two clips are thuspulled 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
Observation sheet(i) Grade of bitumen = 60/70(ii) Pouring temperature °C = 100 oC(iii) Test temperature = 27 oC(iv) Period of cooling (minutes) in Air = 40 min
In water bath before trimming = 30 minIn water bath after trimming = 90 min
Test PropertyBriquette Number Mean
Valuea b cDuctility (cm) 74 76 75
Repeatability %
Reproducibility %
IS Specification
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
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.
7. Softening Point
Significance
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
Glass Beaker
Brass Rings(In Ø=15.9 Mm & Out Ø=17.5mm
Steel Balls ø = 9.5 mm (2.5g)
Metallic Support
Thermometer
Mechanical Stirrer
Temp Controlled Heating Plate
Procedure Heat the bitumen to a temperature between 125oC to
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
Continue….
Place the balls on the rings
Raise the temperature uniformly at 5oC per minute till
the ball passes trough the rings
Note the temperature at which each of the ball and
sample touches the bottom plate of the support
Temperature shall be recorded as the softening point
of the bitumen
Observation table(i) Grade of bitumen = 60/70(ii) Approximate softening point = 40 oC(iii) Liquid used in water bath(water/Glycerin) = water(iv) Period of air cooling (minutes) = 30 min(v) Period of cooling in water bath(minutes) = 15 min
Test PropertySample
a b meanTemperature at each sample
touches bottom plate 42 42 42
Repeatability %
Reproducibility %
IS SpecificationsSoftening Point Repeatability (oC) Reproducibility (oC)
<30oC 2 4
30oC- 80oC 1 2
>80oC 2 4
Bitumen Grades Softening Point (oc)S 35 55-65
A 45, S 45 & A 65 45-60S 65 40-55
A 90 & S 90 35-50A 200 & S 200 30-45
Note: S denotes sources other than Assam petroleum
Discussion
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
Marshall Mix Design
CE 328 Transportation Engineering I
Overview
• Specimen preparation• Properties of the mix• Marshall stability and flow• Optimum bitumen content• Numerical examples
1/4/2012 Marshall Mix Design 134
1/4/2012 Dry Mix Design 135
Gradation for BC surface course of 40 mm
Specimen preparation• Approximately 1200gm of aggregates and
filler is heated to temperature of 1750-1900 C
• Bitumen is heated to a temperature of 1210-1250 C with first trial percentage of bitumen (say 3.5 or 4% by weight of the mineral aggregates)
• Heated aggregates and bitumen are thoroughly mixed at a temperature of 1540-1600 C
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Specimen preparation• Mix is placed in a preheated
mould and compacted by a rammer with 50 blows on either side at temperature of 1380 C to 1490 C
• Weight of mixed aggregates taken for the preparation of the specimen may be suitably altered to obtain a compacted thickness of 63.5+/-3 mm
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Specimen preparation
Marshall Mix Design1/4/2012 138
Thickness63.5+/-3 mm
Diameter 100 mm
Properties of the mix• Theoretical specific gravity Gt
• Bulk specific gravity of the mix Gm
• Percent air voids Vv
• Percent volume of bitumen Vb
• Percent void in mixed aggregate VMA • Percent voids filled with bitumen VFB
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Phase diagram of a bituminous mix
Marshall Mix Design1/4/2012 140
Theoretical specic gravity of mix Gt
• Specific gravity without considering air voids
• Where W1: Weight of coarse aggregate in total mixW2: Weight of fine aggregate in total mixW3: Weight of filler in total mix
Marshall Mix Design1/4/2012 141
Wb: Weight of bitumen in total mix
G1: Apparent specific gravity of coarse aggregate
G2: Apparent specific gravity of fine aggregate
G3: Apparent specific gravity of filler
Gb: Apparent specific gravity of bitumen
Marshall Mix Design1/4/2012 142
Bulk specific gravity of mix Gm
• Specific gravity considering air voids
• Where Wm: Weight of mix in airWw: Weight of mix in waterWm - Ww gives the volume of the mix
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Air voids percent Vv
• Percent of air voids by volume in the specimen
Gt: Theoretical specific gravity of mix
Gm: Bulk or actual specific gravity of mix
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Air voids percent Vv
Marshall Mix Design1/4/2012 145
Percent volume of bitumen Vb
• Percent of volume of bitumen
• W1: Wt of coarse agg.W2: Wt of fine agg.W3: Wt of fillerWb: Wt of bitumenGb: Sp. Gr. of bitumenGm: Bulk sp. gravity
Marshall Mix Design1/4/2012 146
Voids in mineral aggregate VMA• Volume of voids in aggregates• Sum of air voids & volume of bitumen
VMA = Vv + Vb
• where Vv: Percent air voids in the mix• Vb: Percent bitumen content in mix
Marshall Mix Design1/4/2012 147
Voids filled with bitumen VFB• Voids in mineral aggregate frame work
filled with the bitumen
VFB = Vb / VMA X 100
• Vb: Percent bitumen content in mix
VMA: Percent voids in mineral aggregate
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1/4/2012
Marshall stability and Flow value• Marshall stability and flow test provides the
performance prediction measure
• Stability portion of test measures maximum load supported by test specimen at a loading rate of 50.8 mm/min
• Load is applied to the specimen till failure, and maximum load is designated as stability
149
Marshall stability and Flow value• During the loading, an attached dial
gauge measures the specimen's plastic flow (deformation) due to the loading
• Flow value is recorded in 0.25 mm (0.01 inch) increments at the same time when the maximum load is recorded
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Marshall stability and Flow value• Marshall Stability
– Maximum load required to produce failure when specimen is preheated to a prescribed temperature placed in a special test head and the load is applied at a constant strain (5 cm per minute)
• Flow Value– The deformation at failure point expressed in
units of 0.25 mm
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Marshall stability and Flow value
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Apply stability correction• It is possible while making the specimen
thickness slightly vary from standard specification of 63.5mm
• Measured stability values need to be corrected to those which would have been obtained if specimens had been exactly 63.5mm
• Multiplying each measured stability value by an appropriated correlation factors
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Correction factors for Marshall stability values
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Prepare graphical plots• Vary the bitumen content in the next trial by
+ 0.5 % and repeat the above procedure. • Number of trials are predetermined.• Marshall
Test Setup
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Prepare graphical plots1. Binder content versus corrected
Marshall stability2. Binder content versus Marshall ow3. Binder content versus percentage of
void (Vv) in the total mix4. Binder content versus voids filled
with bitumen (VFB)5. Binder content versus unit weight or
bulk specic gravity (Gm)Marshall Mix Design1/4/2012 156
Marshal graphical plots
Marshall Mix Design1/4/2012 157
Determine optimum bitumen content• Average bitumen contents from:
1. Binder content Vs Stability2. Binder content Vs Gm3. Binder content at design Vv
Air voids Vv = 4%
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Marshal graphical plots
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Determine optimum bitumen content• The stability value, flow value, and VFB are
checked with Marshall mix design specification chart
• Mixes with very high stability value and low flow value are not desirable as the pavements constructed with such mixes are likely to develop cracks due to heavy moving loads
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Marshall mix design specification
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Numerical example - 1• The specific gravities and weight proportions
for aggregate and bitumen are as under for the preparation of Marshall mix design
• Volume and weight of one Marshall specimen was found to be 475 cc and 1100 gm
• Assuming absorption of bitumen in aggregate is zero
• Find Vv, Vb, VMA and VFBMarshall Mix Design1/4/2012 162
Solution
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Numerical example - 2• The results of Marshall test for five
specimens is given below. Find the optimum bitumen content of the mix
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Solution• Plot the graphs• bitumen content corresponding to
1. Max stability = 5 %2. Max Gm = 5 %3. 4% air void = 3 %
• Optimum bitumen content = 4.33 %– average of above– Design bitumen content
Marshall Mix Design1/4/2012 166
Thank You
8. Marshall Stability Test
9. Bitumen Extraction Test
10. Traffic studies: Volume study
Other tests