MAKERERE
UNIVERSITY
FACULTY OF TECHNOLOGY DEPT. OF CIVIL ENGINEERING NAME:
KWESIGA IVAN
REG. NO:
07/U/9623/PS
STUDENT NO: 207014939 SIGNATURE: COURSE UNIT: HIGHWAY ENGINEERING – LAB PRACTICAL REPORTS LECTURER:
MR. MUKASA
DATE:
30-11-2009
SOIL TESTS NATURAL MOISTURE CONTENT OF SOIL Objective
To determine the amount of water present in fresh soil expressed as a percentage of the mass of the dry soil. Introduction
Moisture content of soil is the amount of water within the pore spaces in soil grains. Natural moisture content is the amount of water in freshly obtained soil in its natural state. It is dete determ rmin ined ed by oven oven-d -dry ryin ing g the the soil soil at a tem tempe perat ratur uree not not exce exceed edin ing g
. Moi Moist stur uree con conte tent nt
greatly influences the behavior of soil. Standard reference
BS 1377:1990 Apparatus •
Soil sample
•
Weighing balance
•
Metal cans
•
Drying oven at temperature of
-
.
Procedure
Collect a fresh soil sample and divide into four parts by using a rifle box. This will provide the soil from which the samples for the oven will be taken. Clean and dry the moisture cans and weigh each, recording their respective weights. Fill each moisture can with soil from each soil heap and weigh the cans again. Record their weights.
Place the soils samples into the oven for a minimum of 12 hours. Remove the samples and weigh them again. Record the results in a suitable table. Treatment of results sample
A
B
C
D
E
47
45
58
67
5 3 .5
42 . 5
41
53. 5
62
4 8 .5
Mass of can (m3)
1.5
1
1
1
1
Mass of water
4.5
4
4.5
5
5
Moisture content (%)
11
10
8.6
8.2
1 0 .5
Mass of soil + can (m1) Mass of dry soil + can (m2)
Calculation
Compute the moisture content W of the specimen as a percentage of the dry soil mass from the equation:
Moisture content of the soil is 9.7%.
PARTICLE SIZE DISTRIBUTION
Particle size distribution is a necessary classification of soils because it shows the relative distribution of particle sizes in a particular soil type. It makes it possible to determine whether soils are predominantly gravel, sand, clay or silt which will also affect the engineering properties of the soil. Introduction
Wet sieving is performed in order to remove the clay and silt particles in the soils. The soil is first washed on a 75µm sieve and the soil retained is oven-dried to obtain the soil that is passed through the series of sieves to determine the distribution. The results obtained are plotted on a graph with a logarithmic scale and the soil classified by identifying the distribution as being gravel or sand. Apparatus •
Test sieves
•
Tray
•
Evaporating dish
•
Balance
•
Sieve brushes
•
Drying oven
Procedure
First prepare the test sample by air drying soil for over 12 hours. Take a representative sample from the heap of about 2.5kg by rifling. Sieve the sample through the 20mm sieve. This may be skipped since the rifle box apertures are 20mm.
Take the sample and wash it through the 75µm sieve. This washes out the clay and silt particles from the sample. Transfer the retained material from the sieve to an evaporating dish which is placed in an oven at
for 24 hours to ensure complete drying of the sample. Weigh the dry sample.
Stack the sieves in decreasing in order of decreasing aperture size and then pass the soil through the sieves either mechanically or manually. Weigh the mass of soil retained on each sieve and then plot the particle sizes against percentage passing on a graph with a logarithmic scale. Treatment of results
Obtain the total mass on all the sieves. Find the difference between the original mass and the retained sample mass.
Grade the soil from the results plotted on the graph. Classification –gravelly sand weight
%
%
retained
passing
sieve 14.0m
retained
m 10.0m
86
4.8
9 5 .2
m 2.36m
1 61 . 5
9.1
8 6 .1
m 1.18m
9 25
51.9
3 4 .2
m 600µ
1 48
8.3
2 5 .9
m 300µ
1 10
6.2
1 9 .7
m 150µ
1 56 . 5
8.8
1 0 .9
m
1 04 . 5
5.9
5
75µm Pan Total
65.5 25 1782
3.7 1.4 100
1.3 0
Discussion of results
18g of the soil was lost during the analysis. This is due to the particles that get stuck in the sieve spaces and the others that fall out of the sieves during the sieving process and transfer to the weighing pans. The soil is gravelly sand because more than 70% of the particles lie in the region of gravel and the remaining percentage is sand. Conclusion
From the results of the particle size distribution it can be concluded that the soil is suitable for use as highway sub-base.
LIQUID LIMIT- CONE PENETROMETER METHOD Objective
The liquid limit is the moisture content at which soil passes from the liquid to plastic state. The liquid limit provides a method of classifying fine grained soils since the smallest 10% fines determine the properties of the soil such as the shear strength. Introduction
The cone penetrometer test involves determining the liquid limit of a soil sample in its natural state. The soil used is passed through a 425µm sieve. The soil is penetrated using a standard cone and the penetration measured. Apparatus •
425µm sieve
•
Flat glass plate
•
Spatulas
•
Cone penetrometer
•
An airtight container
•
Metal cup
•
Wash bottle containing clean water
Procedure-sample Procedure-sample preparation
Pass the soil sample through 425µm sieve until about 400g of sample are collected. This is sufficient for the plastic limit, liquid limit and linear shrinkage tests. Place the sample on the glass plate and mix it with water from the wash bottle. Using the spatula, mix the sample into a paste. Store the sample in an air tight container for 16-24hours to allow the water to completely permeate the soil.
Liquid limit
Take the sample from the airtight container and place it on a glass plate where it is mixed using palette knives for a few minutes. Add water to a portion of the sample and mix it again until uniformity is attained. Put some of the soil into a container using the palette knife ensuring no air is trapped by tapping it on a hard surface. Smoothen the surface with a straight edge. Place the container directly below the cone and lower it until it just touches the surface of the soil. Slight movement of the container should mark the soil surface. Lower the dial gauge to touch the cone and adjust the reading to zero. Release the cone for 5±1 seconds record the reading on the dial gauge to the nearest 0.1mm. Lift out the cone out clean it. Repeat the procedure for different amounts of water added to the soil. The difference between successive readings should not exceed 1mm for the same amount of water added. Carry out the procedure for about four different amounts of water (15-25mm penetration range) added to the soil and record the values obtained in a suitable table. Each time the sample is penetrated clean the container and wash it before performing another penetration. Take samples from each can for moisture content determination. Treatment of results
Obtain the moisture content of the soil samples. Plot a graph of penetration against moisture content and draw a line of best fit through the points. The liquid limit is the moisture content that produces a penetration of 20mm to the nearest whole number.
Table of results Tin no. Weight of tin +
BR
C
A
2A
2B 23.
2C
3A
3B 3B
3C 3C 24.
4A
4B
4C
wet soil weight of tin +
40
47.5
46.5
2 4 .5
5 16.
22 15.
22
24
5 16.
23
25
22.5
dry soil Weight of tin Moisture
32.5 15
39 39.5 21.5
39 20
17 0.5
5 0.5 43.
5 0.5 43.
15 0.5 48.
16 0. 0.5 51.
5 0. 0.5 50.
15.5 0.5
16.5 0
15.5 0
content Average
42.9
44.4
39.5
4 5 .5
8
3
3
6
0
50.0
51.5
45.2
moisture content Average penetration
42.3
44 . 2
50
48.9
1 7 .0 5
20.03
21.2
23.9
Moisture content at 20mm penetration = 45.5% Liquid limit = 46%
COMPACTION TEST
Objective The objective of the test is to get the relationship between the moisture content and the dry density of compacted soil for a given compaction effort. These are used in specification in works involving compacting of soil.
Main principles The dry density of any given soil depends on the moisture content and the compactive effort used. Compaction is the process of increasing the dry density of a soil by parking the soils more closely. This can be done by vibrating, static load compaction, tampering or kneading. Dry density of a soil increases with the increase in the mechanical effort. However for moisture content, it increases up to a maximum value and then drops. The moisture content at which the maximum dry density is achieved is the optimum moisture content. Thus with the relationship between the dry density and the moisture content for a given compaction effort, the optimum moisture content can be determined which is used in the field.
Reference BS 1377: part 4 Craig’s Soil Mechanics – R.F. Craig
Method BS heavy – using a 4.5 kg rammer
Equipment used •
Cylindrical compaction mould
•
Metal rammer 4.5 kg heavy
•
Balance
•
Moisture cans
•
Large metal tray
•
Measuring cylinder
•
Oven – for determining moisture content
•
Spatulas
Sample preparation Sample was passed through a 20mm sieve and the particles larger than 20mm were removed. The sample was then dived into five representative smaller samples. Each sample was mixed with a different amount of water to give a range of moisture contents. The initial amount water for the first sample was assumed to be 8%, amount of water to be added was computed from the following equation;
Wate Wa terr was was meas measur ured ed by a meas measur urin ing g cyli cylind nder. er. The The each each samp sample le is mixe mixed d with with water water thoroughly until uniform colour is reached. Each sample is further divided into five parts. Each sample is compacted in five layers with each part of every sample receiving 27 blows
Procedure The weight of the mould and the base plate were weighed and weight recorded. W1.The moist soil was placed in the mould and compacted in five layers, each layer receiving 27 blows of a 4.5 kg rammer. The rammer is dropped from a distance of about 450mm.A collar was fixed when the mould filled up before the final layer compaction. After compaction the collar was removed and the soil trimmed till the level of the mould opening. Weight of compacted soil and mould was measured and recorded. W2 Representative samples from top and bottom of the compacted soil were taken to determine the moisture contents. This procedure is carried out for all the five samples with different moisture contents.
Analysis Moisture content of each soil is calculated using the average of the top and bottom moisture contents. Calculate the bulk density;
Dry density was computed using the wet we t (bulk) density and moisture content using the formula;
Dry densities calculated where plotted as ordinates and the moisture contents as abscissas. The line of best fit is drawn and the maximum point was identified and the corresponding dry density and moisture content read off and recorded. This is the optimum moisture content. On the same graph the 0%, 5% and 10% air void lines were plotted using the following equation.
Results;
Weight of mould
6400
6550
6640
6640
6540
+soil(g) Weight of mould(g) weight of soil(g) volume of
5440 960 1000
5440 1110 1000
5440 1200 1000
5440 1170 1000
5440 1100 1000
mould(cm3) bulk density(kgm -3) Dry density(kgm -3)
0.96 0.86
1.11 0.99
1.2 1.06
1.17 1.01
1.1 0.94
9 Moisture content can 1A Mass of can + 28.5
1B 30.5
5 2A 21.5
2B 20.5
0 3A 29.5
3B 19.5
6 4A 33.5
4B 29.5
4 5A 29
5B 50
soil(g) Mass of can + dry
27
26.5
19.8
18
25.8
17.5
30
25
23
47
soil(g) Mass of can(g) Mass water(g) Mass of dry soil(g) Moisture content (w
0.5 1.5 26.5 5.66
0.5 4 26 15.3
0.5 1.7 19.3 8.81
0.5 2.5 17.5 14.2
0.5 3.7 25.3 14.6
0.5 2 17 11.7
0 .5 3 .5 29.5 11.8
0.5 4.5 24.5 18.37
0.5 6 22.5 26.6
0.5 3 46.5 6.45
9
2 13.2
6
6 15.1
%) Average w%
8 10.5
11.5
7 16.6
Optimum moisture content = 13.2% Maximum dry density = 1.060gcm-3 = 1060 kgm-3
PLASTIC LIMIT Introduction
Plastic limit is defined as the moisture content at which the soil becomes plastic on addition of water. Plastic limit and liquid limits are used to determine the plasticity index which is the difference between the plastic limit and the liquid limit. It is proved that the finer the soil the higher the plasticity index. Sample preparation
The sample used for the determination of the plasticity index is the soil that passes through the 425µm sieve. About 40g of sample are required for the experiment and the sample is prepared in a similar way to the liquid limit. Equipment •
2 flat glass plates
•
2 palette knives or spatulas
•
Clean water
•
Moisture content apparatus
•
3mm diameter rod
Standard reference
BS 1377: part 2: 1990 Procedure
From the sample of 40g divide out 2 portions of 20g each and mould them into balls on the glass plates until they are dry enough to crack on the surface.
Take a sample of soil from each ball for separate plastic limit determination. Mould the samples into threads of about 6mm and then knead them between the thumb and the first finger into threads of 3mm diameter. Compare the thread to the rod to ensure it is approximately 3mm. Roll the thread until it starts to crack and shear longitudinally. Remould the sample and then repeat the procedure until the thread shears. Transfer the samples to separate moisture cans to determine the moisture content of the two samples. The moisture content of the two samples should not differ by more than 0.5%, otherwise the experiment is repeated. The plastic limit of the sample is the average of the two moisture contents. Treatment of results Tin no. Weight of tin (g) Tin + sample (g) Tin + dry sample (g) Moisture content (%)
3T 6.5 10 . 5 10 12.5
A2 6 10 9 .4 9 1 2 .8
Calculations
Conclusion
Plastic limit of the soil is 12.7% and the plasticity index is 33.3%.
CALIFORNIA BEARING RATIO (CBR)
The load bearing capacity of the sub grade is the main factor in determining the required thickness of a flexible pavement for roads and airfields. The strength of the sub grade, sub base, and base course materials are expressed in terms of their California Bearing Ratio (CBR) value. The California Bearing Ratio is the ratio of test load corresponding to chosen penetration to the standard load for the same penetration. One point CBR
The one point CBR method was used to determine the wet and dry CBR values of the soil samples obtained. Objective
The CBR value is a requirement in the design of pavements of natural gravel. This test is performed to determine the bearing ratio of a given soil sample under a given applied loading. The bearing ratio is obtained by the relationship between force on the plunger and penetration of the plunger, when the cylindrical plunger penetrates the soil at a given rate. The CBR value is used in the design of flexible pavements, granular base courses, rigid pavements, air field runways. This value is also used to determine suitable thicknesses for the different layers of pavements, which will withstand the anticipated traffic conditions in terms of axial loadings and traffic frequency and to design the life span of the pavement. Equipment •
BS 20mm sieve
•
CBR mold
•
CBR penetrating machine
•
Weighing balance
•
Filter paper and surcharge discs
Sample preparation
A representative sample was obtained using the riffling method. The soil was sieved on a 20mm sieve and the material passing collected onto a large tray.6 kg of the soil was collected onto a small tray. The soil was mixed with a volume of water that would cause it to reach its optimum moisture content (OMC %) obtained from the BS Heavy compaction test of this soil. The soil was sealed in a polythene bag and stored for 24 hours before compacting into the CBR mould fitted to a perforated base plate. Compaction in the CBR mould was done in five equal layers with each layer receiving 62 blows being uniformly distributed over the surface using the 4.5kg rammer. The collar on the mould was removed and the soil flush trimmed to the top of the mould. The weight of the soil in the mould together with its base plate was measured and recorded. Moisture content samples were taken and placed in the drying oven at
c to determine the
moisture content (w %). The procedure was repeated for the second mould. Procedure for soaking
A filter paper was placed on the top surface of the soil in one of the moulds. Annular surcharge discs were placed on top of the filter paper in the mould to provide a water tight joint. The mould assembly was placed in the soaking tank with the perforated base plate at the bottom for four days after which it was removed and left to allow for draining for 15 minutes. Testing of the specimen
After four days, the mould containing the specimen was removed from the soaking tank and the annular surcharge discs removed. The mould was placed in position, with the perforated base plate resting on the testing machine. The plunger on the testing machine was brought into contact with the surface of the soil and the readings on the force and penetration dial gauges set to zero. A penetrating force was applied on the plunger and the load at penetration of 0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0 and 7.5 of the needle recorded. The mould was inverted and the perforated base plate at the bottom removed. The testing procedure was repeated for the bottom surface of the soil.
The same procedure was carried out on the dry sample immediately after compacting and therefore no filter paper was required.
Results
A force penetration curve is plotted from the following steps; Calculate the force applied to the plunger from each reading of the loading ring observed during the penetration test. Each value is plotted as ordinate against the corresponding penetration and a smooth curve is drawn through the points. If the curve is concave, a tangent is drawn at the point of the steepest slope to produce an intercept at the abscissa. This is the corrected zero point.
Calculation of CBR Plunger value at 2.5mm and 5mm penetration are recorded from the force penetration curve. CBR is calculated from the following equations;
The plunger force P, is in KN. The higher value of the two is taken as the CBR value
Density calculations 1. The inte interna rnall volume volume of the the mould mould is is measur measured, ed, Vm ( cm3) 2. Bulk Bulk densit density y is calcul calculated ated from from the the equatio equation; n;
M3 – mass of the soil, mould and the base plate (g) M2 – mass of mould and base plate (g) 3. Dry Dry den densi sity ty is got got from from;;
W is the moisture content.
4. If dry density density for soaked soaked is required, required, it is calculat calculated ed from equati equation; on;
A is the area of the cross section of the mould (mm 2) X is the increase in sample height after swelling (mm)
Results Density Determination Mould No
1
2
Mass of mould + soil
g
10020
9870
Mass of mould
g
4740
4740
Mass of soil
g
5280
5130
3
2305
2305
Moist density
3
g/cm
2.291
2.226
Dry density
g/cm3
2.017
1.888
Volume of the mould
cm
Wet CBR Container Mass of container(g) Mass of sample + container(g) Mass of dry sample + container(g) Mass of sample(g) Mass of dry sample(g) Mass of moisture(g) Moisture content (w %)
Dry CBR
1TW 0.5
2TW 0.5
40.5
44.5
36.0
39.0
40.0
44.0
35.5
38.5
4.5
5.5
12.7%
14.3%
Moisture content = (12.7% + 14.3%)/2 + 11.2%)/2 = 14%
Container Mass of container(g) Mass of sample + container(g) Mass of dry sample + container(g) Mass of sample(g) Mass of dry sample(g) Mass of moisture(g) Moisture content (w %)
T1 0.5
T2 0 .5
55.5
69.5
50.0
62.5
55.0
69.0
49.5
62.0
5.5
7 .0
11.0%
11.2%
Moisture content = (11.0% = 11%
DRY CBR
Wet CBR Dial gauge reading
Dial gauge reading Botto Top m
Penetration (mm)
Top
Bottom
Penetrati on (mm)
0.5
0.24
0.48
0.5
0.37
1.06
1
0.37
0.55
1
0.5
1.66
1.5
0.48
0.63
1.5
0.61
2.16
2
0.58
0.69
2
0.71
2.53
2.5
0.66
0.74
2.5
0.87
2.77
3
0.77
0.82
3
0.95
2.93
3.5
0.84
0.87
3.5
1.08
3.06
4
0.95
0.92
4
1.19
3.19
4.5
1.03
0.98
4.5
1.29
3.33
5
1.11
1.03
5
1.43
3.43
5.5
1.21
1.06
5.5
1.48
3.48
6
1.32
6
1.61
3.54
6.5
1.43
6.5
1.72
3.59
7
1.56
7
1.79
3.7
7.5
1.69
7.5
1.93
3.75
DRY CBR . .
Force Top
CBR
Bottom
Top
Bottom
Average CBR
2.5mm Penetration
0.66
0.77
5 .0
6.0
5.5
5.0mm Penetration
1.11
1.03
6
5
5 .5
WET CBR . .
Force Top
CBR
Bottom
Top
Bottom
Average CBR
2.5mm Penetration
0.87
2.77
7
21
14
5.0mm Penetration
1.43
3.43
7
17
12
Dry CBR is 5.5%. Wet CBR is 14%.
AGGREGATE TESTS AGGREGATE IMPACT VALUE (AIV) Introduction
Aggregates used in road construction are required to be strong enough to resist crushing under traffic loads. Aggregate impact value (AIV) is one of the tests used to measure the strength of aggregates. Aggregate Impact value is the relative measure of the resistance of aggregates to sudden shock or impact. Sample preparation
The test can be performed in dry or soaked condition. For the test performed, the dry condition was used. The sample used in the test passed through the 14mm sieve and was retained on the 10mm sieve. Equipment •
Test sieves (10mm and 14mm)
•
Metal cylinder (75mm diameter and 50mm depth) and known weight weight
•
Metal tray of known mass
•
Riffle box
•
Tamping rod
•
Brush with stiff bristles
•
Aggregate impact testing machine
Procedure
Obtain a sample for the test by sieving with a 14mm and 10mm sieve. The sample larger than 14mm and smaller than 10mm is discarded. What remains is used for the test. The sample collected should be enough to fill the metal cylinder to the brim. Fill the cylinder completely with the aggregate and then tamp the aggregate 25 times using the tamping rod. Remove any excess aggregate by rolling the rod over the top of the cylinder and add aggregate in any spaces in the cylinder. Place the aggregate impact machine on a level surface and fix the cup in position in the machine. Place the cylinder in the cup and tamp the sample 25 times again with the tamping rod. Raise the hammer so that its height is 380±5mm above the top of the aggregates. Release the hammer to drop freely 15 times at intervals of not more than 1 second between each blow. Remove the cylinder and weigh it with the sample. Empty the sample onto a tray ensuring the cup is cleaned using a brush. Sieve the sample with a 2.36mm sieve until no significant amount passes and record the mass retain and mass that passes through the sieve. If the total mass exceeds the initial mass by more than 1g, repeat the test.
Results and calculations
Mass of cup = 2585g Mass of sample and cup = 3280g Mass of sample Mass retained on sieve = 631.0g Mass passing through sieve
AGGREGATE CRUSHING VALUE (ACV) AND TEN PERCENT FINES (TFV) Introduction
Aggregates used for road paving should be strong enough to withstand the traffic wheel loads without failing due to crushing. Aggregate crushing value test is used to measure the strength of coarse aggregates. Aggregate crushing value test (ACV) is used to measure the resistance of an aggregate to gradually applied loads. It is determined by measuring the amount of material passing through a specified sieve after crushing under a 400KN load. It is preferred to carry out the 10% fines test simultaneously with the ACV test where the samples are crushed at 50KN, 100KN, 150KN and 400KN respectively. 10% fines test is used to determine the resistance of the aggregates to crushing under gradually applied loads. Sample preparation
The sample used for the test is the material retained when the aggregate retained on the 14mm sieve and passing through the 10mm sieve is discarded. References
BS 812: Part 110: 1990 Equipment •
Tamping rod
•
Open ended steel cylinder
•
Compression testing machine
•
Rifle box
•
Metal tray
•
Brush with stiff bristles
•
Balance
•
Test sieves
Procedure
Obtain sufficient material after sieving using the 14mm and 10mm sieves. With the steel cylinder placed on its base, fill it to a third of its volume with aggregates. Tamp the aggregates 25 times with the tamping rod. Do this at two thirds and when the cylinder is completely filled. Level the surface using the tamping rod and fill any voids in the cylinder. Place the plunger on top of the aggregate surface so that it is horizontal. Place the cylinder and plunger in the crushing test machine. Apply the crushing force for about 10minutes. Release the crushing force and remove the steel cylinder. Empty the material from the cylinder onto a tray. Remove the remaining material using the brush brush and and then then weigh weigh the metal metal tray tray and and crushed crushed sample sample (
). Record Record the weight weight obtained obtained to
the nearest 1g. Sieve the crushed material through a 2.36mm sieve and weigh the sample retained and sample that passes through the sieve. Record the two masses. If the sum of material passing throu rough the sieve an and the sa sample ret retained
differs from rom the ini initial ma mass rec recorde rded by
more than 10g, discard the sample. Treatment of results Force (KN) Mass of crushed specimen
50
10 0
15 0
40 0
m1(g) Mass of retained sample
3 58 0
348 1
35 7 5
3 48 1
m3(g) Mass passing m2(g)
3 44 0 1 40
323 5 2 43
31 7 0 4 02
2 70 0 735
Calculation of ACV
BITUMEN TESTS PENETRATION TEST Introduction
The penetration test is used to measure the consistency of a bituminous material expressed as distance in tenths of a millimeter when a standard needle penetrates the material under known loading conditions. A needle of specified dimensions and loaded with a standard load is allowed to penetrate the bitumen at a specified temperature. The distance the needle penetrates is called the penetration value. Standard reference
ASTM D 5-86: Penetration of bituminous materials Equipment •
Standard penetrometer
•
Penetration needle (2.5g)
•
Standard 50g load
•
Needle holder
•
Stop watch
•
Penetration tins
Sample preparation
Heated bitumen is poured into 3 penetration tins to a depth of 10mm higher than the expected penetration depth.
Allow the samples to stand and cool at room temperature for 24 hours. Cover the samples with foil or glass plates to protect them from dust. The test is performed at room temperature (25 ) and the the pene penetrat tration ion is is perform performed ed for for 5 second seconds. s. Procedure
Set up the penetrometer ensuring it is level. Check that the needle holder can move freely unobstructed. Clean the needle with a solvent like toluene and then set the penetration tin containing the sample below the needle. The needle is lowered until it just touches the surface of the bitumen. Adjust the dial gauge to the zero mark and then release the needle to penetrate the sample material for 5 seconds. Record the reading on the dial gauge. Repeat the test for the two other samples recording the penetration values in millimeters. The penetration value of the bitumen is obtained by calculating the average of the penetration of the 3 samples.
Treatment of results Penetration
Penetration(m
tins
m) P1 P2 P3
10.5 10.5 10.6
Penetration Penetration of the bitumen is 11mm.
SOFTENING POINT TEST Introduction
The softening point of bitumen is the temperature at which bitumen begins to show fluidity. It is used to check the uniformity of different bituminous supplies and sources. The softening point is also used to determine the temperature at which the bitumen will begin to flow during service conditions. The test is performed by raising the temperature of the sample at a constant rate and the temperature read at the point where the bitumen undergoes a specified deformation. A 3.5g steel ball is placed on the sample held in a brass ring in a water bath. Water is used for sample sampless with with softe softenin ning g point pointss below below 80 80 The temperatu temperature re is raised raised at 5
and glyceri glycerin n for soften softening ing poin points ts great greater er than than 80 80 .
per minute minute until until the the bitumen bitumen begins begins to deform and the the ball
falls through the ring. The temperature is read when the bitumen and the steel ball touch the base plate 25mm below. Equipment •
Boiled water with a heater
•
Water bath
•
2 brass rings
•
2 steel balls (3.5g)
•
Smooth glass plate
•
Thermometer
•
Spatula
•
Glass container
Sample preparation
Heat the sample to a temperature high enough to liquefy the bitumen. Pour the sample into the brass rings which are placed on the smooth glass surface. Fill the rings with the bitumen. Allow the bitumen to cool for 24 hours before performing the test. Cut the excess bitumen with a heated spatula. Procedure
Place the brass ring into the glass container with the ring holder. Fill the container with water up to about 110mm depth. Place the steel ball on the rings and maintain a constant temperature for about 15minutes until a uniform temperature is attained. Transfer the glass container to the heating unit. Heat the the water unit unit a uniform uniform temperature temperature rise rise of 5
per minute minute is achieved. achieved. This This is done done by by
recording recording the the temperature temperature every every minute minute until until the temper temperature ature is within ±0.5
of the desired desired
rate. The water is heated until the bitumen softens allowing the steel ball to fall through the brass ring and touch the bottom plate. The temperature at this instant is recorded. The temperatures for the ring and ball for each sample are recorded and the difference betw betwee een n the the two shou should ld not not exc exceed eed 1 . Results Sample number
Temperature
1
45.5
2
46.5
Softening point is obtained by finding the average of the two temperatures Softening point of the bitumen is
