Lab Report - Copy Edited
Lab Report - Copy Edited
Lab Report - Copy Edited
LABORATORY REPORT
1. CBR test.
2. Aggregate impact value test.
3. Shape test of aggregates
4. Softening point (Ring and ball test) of bitumen.
5. Penetration value test of bitumen.
1
Preparation and transportation of test samples:
Sample preparation: Many samples will require some preparation before being sent to the laboratory
for testing, particularly if their large sizes makes them difficult to handle or because they require special
protection.
Sample reduction: If the sample is delivered larger than required for a particular testing programme, it
must be divided to obtain a sample of the required size. In order to ensure the test sample represents the
original material, it is necessary to divide the original sample either by quartering or by using a sample
divider (Riffle box).
Sample transportation:
All samples should be carefully packed and labelled before transporting them to the laboratory. Sample
bags must be strong enough to withstand rough handling and be of a type which prevents loss of fines or
moisture from the sample, e.g. thick polythene bags inside jute bags. The use of steel drums for large
bulk samples could also be considered. Water samples in glass or plastic containers will require
particular care in handling. Undisturbed samples should be placed in wooden boxes and packed in
sawdust or similar material to provide added protection. Collision between tubes in transit can easily
damage sensitive samples.
Storage:
Storage of all samples should be in an orderly and systematic manner so that they can be subsequently
located easily. The storage facility itself should be a secure area, free from the risk of contamination or
other harmful influences. Undisturbed samples may be damaged by vibration or corrosion of tubes and
should be stored with especial care. Tubes containing wet sandy or silty soils should be stored upright
(suitably protected against being knocked over), to prevent possible slumping and segregation of water.
The end caps of tube samples which are to be stored for long periods should be sealed with wax, in
addition to the wax seal next to the sample itself. Samples which have been tested should not be
disposed of without the authority of the laboratory section head.
Sample Drying: Many tests require the material to be drier at the start of the test than the sample as
obtained from the field. Some means of drying the sample must, therefore, be utilised. In the case of
liquid and plastic limit tests, it is essential that the material is air dried and, as a general rule, it is
preferable to dry samples in the air as opposed to drying in size of the sample and in general should not
be smaller than 1.5 times the maximum particle size of the sample If the sample is still too large, one of
the containers may be put aside and the material from the other container is passed through the sample
divider again.
Air drying: This is essential for liquid and plastic limit tests and is the preferred procedure for all other
tests. The sample should be spread out in a thin layer on a hard clean floor or on a suitable metal sheet.
Ordinary corrugated galvanised roofing sheets are perfectly satisfactory for this purpose. The material
should be exposed to the sunlight and should be in a layer not more than 20 mm thick. Cohesive
materials such as clays, require breaking by hand or with a rubber mallet into small pieces, to allow
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drying to take place without too much delay. The soil should periodically be turned over and a careful
check should be made to ensure the material is removed to a sheltered place if it starts to rain. In the case
of soft stone or gravels, care should be taken to ensure only lumps of cohesive fines are broken up and
that the actual stone particles are not destroyed. In the case of fine-grained materials, it is generally
beneficial to the later stages of testing to pass the dried particles through a No. 4 sieve. Air drying should
not normally take longer than 2 to 3 days if carried out correctly.
Oven drying. Oven drying should only be employed where air drying is not possible. Oven drying will
not normally have any detrimental effect on the results for sound granular materials such as sand and
gravel, but may change the structure of clay soils and thus lead to incorrect test results. Oven drying
must never be used in the case of liquid and plastic limit tests. In oven drying the temperature should not
exceed 1100C and the material should be dried as quickly as possible by spreading in thin layers on
metal trays. Periodically, the material should be allowed to cool before testing is commenced.
Sand-bath drying: In certain cases an oven may not be available but the sample must be dried quickly;
sand bath drying may then be utilised. The sand-bath consists simply of a strong metal tray or dish which
is filled with clean coarse sand. The sand bath is placed on some form of heater such as a kerosene stove,
a gas ring or an electric ring. The sample to be dried is placed in a heatproof dish which is embedded in
the surface of the sand. A low heat should be applied so that the sand becomes heated without causing
damage to the bath. The sample should be stirred and turned frequently to ensure the material at the base
does not become too hot. The material should be allowed to cool before testing is commenced.
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EXPERIMENT NO – 1
Heavy
compaction 5 4.89 45 56
4. Adjustable stem, perforated plate, tripod and dial gauge: The standard procedure requires that the
soil sample before testing should be soaked in water to measure swelling. For these purpose these
accessories are required.
5. Annular weight: In order to simulate the effect of over lying pavement weight, annular weights
each of 2.5 kg and 147mm diameter are placed on top of the specimen, both at the time of
soaking and testing the samples, as surcharge.
6. Sieves sizes: 20mm, 4.75mm, oven, balance, coarse filter etc. equipments are required.
4
Line diagram:
5
PROCEDURE:
1. Preparation of test specimen: As per the ISI, the CBR test may be performed on undisturbed soil
specimen obtained by fitting a cutting edge to the mould or on remoulded specimens. The
material used in the remoulded specimen shall pass a 20-mm IS sieve. About 20 to 45kg of
material is sieved and dried through 20mm sieve. If there is noteworthy proportion of material
retained on 20mm sieve, allowance for larger materials is made by replacing it by an equal
weight of material passing 20mm sieve and 4.75mm sieve. The optimum moisture content and
maximum dry density of soil are determined by adopting either IS light compaction (Proctor
Compaction) or IS heavy compaction (Modified Proctor Compaction) as per the requirement. In
case the most of the sample pass through 4.75mm sieve, then the dry pulverised sample is sieved
through 4.75mm sieve and the portion passing this sieve is only used for this test. Remoulded
soil specimen may be compacted either by static compaction or by dynamic compaction.
Statically Compacted Specimen: The batch of soil is mixed with water to give the required moisture
content. The correct weight of moist soil to obtain the desired density is placed in the mould and
compaction is attained by pressing the spacer disc using a compaction or jack.
The preparation of a soil specimen by dynamic compaction or ramming is more commonly
adopted and is explained below:
Dynamically Compacted Specimen: A representative sample of the soil weighing approximately 5.5kg
for granular soil and 4.5 to 5kg weight for fine grained soils is taken and mixed thoroughly with water
up to the optimum moisture content or field moisture content if specified so. The spacer disc is placed at
the bottom of the mould over the base plate and a coarse filter paper is placed over the spacer discs. The
moist soil is to be compacted over this in the mould by compacting either the IS light compaction or the
heavy IS compaction.
a) For IS light compaction, the soil to be compacted is divided into three equal parts, the soil is
compacted into three equal layers, each of compacted thickness about 44mm by applying 56
evenly distributed blows of the 2.6kg rammer.
b) For IS heavy compaction, the soil is divided into five equal parts. The soil is compacted in five
equal layers, each of compacted thickness about 26.5mm by applying 56 evenly distributed
blows of the 4.89kg rammer. After compacting the last layer, the collar is removed and the
excess soil above the top of the mould is evenly trimmed off by means of the straight edge. It is
important to see if the excess soil is to be trimmed off while preparing each specimen is of
thickness about 5mm; If not the weight of soil taken for compacting each specimen is suitably
adjusted for repeat tests so that the thickness of the excess layer to be trimmed off is about 5mm.
Any hole that develops on the surface due to removal of coarse particles during trimming may be
patched up with smaller size materials. Three such compacted specimens are prepared for the
CBR tests. About 100gm of soil samples are collected from each mould for moisture content
determination from trimmed off portions.
6
2. The clamps are removed and the mould with the compacted soil is lifted leaving below the
perforated base plate and spacer disc which is removed. The mould with the compacted soil is
weighed. A filter paper is placed on the perforated base plate, the mould with compacted soil is
inverted and placed in position over the base plate (such that the top of the soil sample is now
placed over the base plate) and the clamps of the base plate are tightened. Another filter paper is
placed on the top surface of the soil sample and the perforated plate with adjustable stem over it.
Surcharge weight of 2.5 or 5kg weight are placed over the perforated plate and the whole mould
with the weights is placed in a water for soaking such that water can enter specimen from both
top and bottom. The swell measuring device consisting of the tripod and the dial gauge are
placed on the top edge of the mould and the spindle of the dial gauge is placed touching the top
of the adjustable stem of the perforated plate (see fig.2). The initial dial gauge reading is
recorded and the test is kept undisturbed in the water tank to allow soaking of the soil specimen
for four full days or 96 hours. The final dial gauge reading is noted to measure the expansion or
swelling of the specimen due to soaking.
3. The swell measuring assembly is removed, the mould is taken out of the water tank and the
sample is allowed to drain in a vertical position for 15 minutes. The surcharge weights, the
perforated plate with stem and the filter paper are removed. The mould with the soil sample is
removed from the base plate and is weighed again to determine the weight of the water absorbed.
4. The mould with the specimen is clamped over the base plate and the same surcharge weights are
placed on the specimen such that the penetration test could be conducted. The mould with the
base [plate is placed under the penetration plunger of the loading machine. The penetration
plunger is seated at the centre of the specimen and is brought in contact with the top surface of
the soil sample by applying a seated load of 4kg.
5. The dial gauge of the proving ring (for load reading) and the penetration dial gauge reading are
set to zero.
6. The load is applied through the penetration plunger at a uniform rate of 1.25mm per-minute by
setting the gear at constant rate of 1.25mm/min.
7. The load reading are recorded at penetration readings of 0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0,
5.0, 7.5, 10.0 and 12.5mm. In case the load readings start decreasing before 12.5mm penetration,
the maximum load value and the corresponding penetration value are recorded. After the final
reading, the load is released and the mould is removed from the loading machine.
8. The proving ring calibration factor is noted so that the load dial values can be converted into load
in kg also find the least count of penetration dial gauge reading to convert into mm.(The present
our laboratory machine, the proving ring calibration factor =0.99kg/div., the deflection dial
gauge L.C=0.01mm/div.)
9. About 50gm of soil is collected from the top three cm depth of the soil sample for the full
determination of moisture content (w). Also weigh the mould with full soil and empty and
determine dry density (γd).
7
=W-Wm/ Vm g/cc
W= Weight of mould with moist compacted soil in gm.
Wm= Weight of empty mould in gm.
Vm= Volume of the mould in cc.
N.B. - In case of unsoaked test, (i) and (ii) are performed.
Formulae to calculate the expansion ratio and CBR value:
The swelling or expansion ratio is calculated from observation during the swelling test using this
formula:
Expansion ratio= 100(df-dt)/h
Where df= Final dial gauge after soaking in mm.
dt = initial dial gauge reading before soaking in mm
h= Initial height of the specimen in mm.
8
Observation sheet:
Compaction moisture content =
Dry density =
Condition of test specimen: soaked/unsoaked
Moisture content: a) At top 3cm layer after soaking =
b) Average after soaking =
Proving ring calibration factor =
Surcharge weight =
Period of soaking =
Expansion ratio =
Sample no. Dial gauge Penetration in Proving ring Load on CBR value at
reading in div. mm dial gauge plunger in kg 2.5 and 5mm
reading in div. from graph
(4)
(2) (5) (6)
(1) (3)
1 0 0 CBR at
50 0.5 2.5mm=
100 1.0
150 1.5
200 2.0 CBR at 5mm=
250 2.5
300 3.0
400 4.0
500 5.0
750 7.5
1000 10.0
1250 12.5
(Table for sample 2)
(Table for sample 3)
Average CBR value at penetration 2.5/5.0mm= %
Discussion:
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EXPERIMENT NO. 2
OBJECTIVE: To determine the aggregate impact value of coarse aggregates as per IS: 2386
(Part IV) - 1963.
APPARATUS:
iv) A tamping rod of 10mm circular cross section and 230mm length, rounded at one end
v) Oven
LINE DIAGRAM:
PICTORIAL IMAGE:
10
Fig: Impact testing machine
THEORY:
Toughness is the property of a material to resist impact. Due to traffic loads, the road
stones are subjected to the pounding action or impact and there is possibility of stones breaking
into smaller pieces. The road stones should therefore be tough enough to resist fracture under
impact. A test designed to evaluate the toughness of stones i.e., the resistance of the stones to
fracture under repeated impacts may be called an impact test for road stones impact test may
either be carried out on cylindrical stone specimens as in Page Impact test or on stone aggregates
as in aggregate impact test. The Page Impact test is not carried out now-a-days and has also been
omitted from the revised British Standards for testing mineral aggregates. The aggregate impact
test has been standardized by the British standards institution and the Indian Standards
Institution.
The aggregate impact value indicates a relative measure of the resistance of an aggregate
to a sudden shock or an impact, which in some aggregates differs from its resistance to a slow
compressive load. The method of test covers the procedure for determining the aggregate impact
value of coarse aggregates.
OBSERVATION
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Sl. Net weight of The fraction The fraction Aggregate
No. Aggregate in the Passing through Retained on Impact value
Measure in gm. 2.36 mm IS sieve 2.36 mm IS =
in gm. Sieve in gm. (B/A)*100%
(A) (B) (C)
Average value
CONCLUSION:
12
EXPERIMENT NO. 3
Objective: Determine the Flakiness and elongation index of coarse aggregates.
Apparatus required:
1. Thickness gauge
2. Length gauge
3. Tray
4. IS sieves of sizes
Theory:
The particle shape of the aggregate mass is determined by the percentage of flaky and
elongated particles in it. Aggregates which are flaky or elongated are detrimental to higher
workability and stability of mixes.
Flaky and elongated aggregate particles tend to break under heavy traffic loads.
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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.
Flakiness Index is the percentage by weight of particles in it, whose least dimension
(Thickness) is less than three-fifths of its mean dimension. The test is not applicable to
particles Smaller than 6.3 mm in size.
Elongation Index is the percentage by weight of particles in it, who’s largest dimension
(Length) is greater than one and four-fifths times its mean dimension. The test is not
applicable to particles smaller than 6.3 mm in size.
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
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 x1 x2….Xi are the weights of material passing the different thickness gauges then:
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Passing Retained Wt. Of the Thickness Weight of
through on I.S. fraction gauge size, aggregate in
I.S. Sieve, Sieve, consisting of at (0.6 times the each
(mm) (mm) least 200 mean sieve) fraction passing
pieces (gm.) (mm) thickness gauge
(gms)
25 20 W1 13.5 X1
20 16 W2 10.8 X2
16 12.5 W3 8.55 X3
12.5 10 W4 6.75 X4
10 6.3 W5 4.89 X5
W total= X total=
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Fig: Length gauge
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 x1, x2…
Xi are the weights of material retained on different length gauges then:
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Passing Retained Wt. Of the Length Weight of
through on I.S. fraction gauge size, aggregate in
I.S. Sieve, consisting of (1.8 times each fraction
Sieve, (mm (mm) at least 200 the mean retained on
length gauge
pieces (gm.) sieve) (mm) gms
25 20 W1 40.5 X1
20 16 W2 32.4 X2
16 12.5 W3 25.5 X3
12.5 10 W4 20.2 X4
10 6.3 W5 14.7 X5
Total W= Total X=
RESULT:
FLAKINESS INDEX=
ELONGATION INDEX=
LIMITS:
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EXPERIMENT NO.4
NAME OF THE EXPERIMENT: Softening point test (Ring and ball test) of bitumen.
OBJECTIVE:
To determine the softening point of asphaltic bitumen and fluxed native asphalt, road tar, coal tar
pitch and blown type bitumen as per IS: 1205 - 1978.
THEORY:
Bitumen does not suddenly change from solid to liquid state ,but as the temperature increases it
gradually becomes softer until it flows readily .A semi solid state bitumen grades need sufficient
fluidity before they are used for application with the aggregate mix .For this purpose bitumen is
sometimes cut back with a solvent like kerosene .The common procedure however is to liquefy
the bitumen by heating .The softening point is the temperature at which the substance attains
particular degree of softening under specified condition of test . For bitumen it usually
determined by Ring and Ball test. Brass ring test containing the test sample of bitumen is
suspended in liquid like water or glycerine at a given temperature. A steel ball is placed upon the
bitumen and liquid medium is then heated at a specified distance below the ring is recorded as
the softening point of a particular bitumen. The apparatus and test procedure are standardized by
ISI. It obvious but harder grade bitumen possess higher softening point than softer grade
bitumen.
APPARATUS:
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Fig: Ring and ball apparatus
PROCEDURE:
i) The apparatus is assembled with the rings, thermometer and ball guides in position.
ii) The beaker is filled with boiled distilled water at a temperature 5.0 ± 0.5oC per minute.
iii) With the help of a stirrer, stir the liquid and heat is applied to the beaker at a temperature
of 5.0 ± 0.5oC per minute.
iv) The heat is applied until the material softens and the ball is allowed to pass through the
ring.
v) The temperature is recorded at which the ball touches the bottom, which is nothing but the
softening point of that material.
i) The procedure is the same as described above. The only difference is that instead of water,
glycerine is used and the starting temperature of the test is 35oC.
OBSERVATION:
19
CONCLUSION:
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EXPERIMENT NO. 5
THEORY:
The penetration of a bituminous material is the distance in tenths of a mm, that a standard
needle would penetrate vertically, into a sample of the material under standard conditions of
temperature load and time.
APPARATUS REQUIRED:
i) Penetrometer
THEORY:
The penetration test is widely used world over for classifying the bitumen in to different
grades. The ISI as standardized the penetration test equipment and the test procedure in
figure7.1. Even though it is recognized that the empirical test like penetration, softening point
etc. cannot only fully qualify the paving binder for its temperature susceptibility
characteristics the simplicity and quickness of operation of this test cannot be ignored for
common use.
LINE DIAGRAM:
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PROCEDURE:
i) The bitumen above the softening point (between 75 and 100 oC) is softened. It is stirred
thoroughly to remove air bubbles and water.
ii) It is poured into a container to a depth of at least 15mm in excess of the expected
penetration.
v) The needle is adjusted to make contact with the surface of the sample.
vii) With the help of the timer, the needle is released for exactly 5 seconds.
OBSERVATION:
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CONCLUSION:
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