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Civil engineering works such as the construction of building, structure, dam, and other structures are dealing with soil as base of the structure. The base must be a strong layer of soil to cater all the vertical load and weight of the structure. If the soil are failed to cater the load of the structure and become weak, a failure will happen and maybe the structure will be collapse or it will be tilted. Therefore, the proper analysis of soil is recommend to ensure that those structures remain safe and as precaution to settling or collapse. A systematically study of the soil in specific location is important in order to determine the characteristic and parameter of the soil. A soil sample must be collected from a job site and tested to evaluate the soil's engineering properties quantitatively.
Soil testing is a compulsory an indicated as preliminary investigation in an overall construction design project. Soil conditions are not the same between locations to another location, hence there is no construction site presents soil conditions similarly to other site. In most instances, soils are mixtures of particles of many sizes, shapes, and parent materials. So, the soil behavior is more difficult to determine than the behavior of material but the soil conditions at every site must be thoroughly investigated prior to detailed design stage.
A laboratory tests are needed to determine the soil condition in order to get actual data especially for design parameter. In highway or pavement works, California Bearing Ratio (CBR) test is a test that widely used to measure of a resistance of compacted soil to penetration. The resistance is related with the suitability of the soil for base or sub base use. This method was introduced by the California Division of Highways in 1930s, following an investigation of pavement failures throughout the state. The CBR values are usually used to design the thickness of pavement that will be layered on top of the sub grade layer. There are a few published correlations that can help a pavement engineer to predict the CBR value since 1960.
In Malaysia, practicing engineers seldom use these correlations as it may be due to its unproven results on the Malaysia soils. Although there are several researches had been carried out by our local universities, there are no extensive data have been collated from a number of projects in Malaysia to verification purposes.
1.2 Problem Statement
Civil engineer always encounters difficulties to obtain the CBR values for pavement design. In Malaysia, inadequate soil investigation data due to budget constraint and poor planning of soil investigation work are frequently happened. There are no established correlations of CBR value with that can help our engineer to predict the CBR value for Malaysia soil type. So, the laboratory work should be done for getting the CBR value. It will take high cost for the highway construction. In addition, the laboratory CBR test required a relatively large soil sample and it is time consuming. Therefore, if there is established correlation between CBR and physical properties of soil for specified types of soil or localized area, they will reduce the cost and number of CBR test to be performed. This study will help an engineer to choose appropriate correlation which is suitable to be use for Malaysia type of soil.
1.3 Objectives of the Study
The main aim of the study is to find the correlation between California bearing ratio (CBR) value and grading properties of soil that best fit Malaysia type of soils. In order to achieve this aim, the specific objectives for this study are as the followings:
To compare the published correlation for CBR value and the grading characteristic of soil based on collected data in UiTM Shah Alam, Malaysia.
To obtain a correlation between CBR value and the grading properties of soil that is suited to types of soils in UiTM Shah Alam, Malaysia.
1.4 Scope of the Study
The study covers only the Malaysian practices in predicting CBR values for pavement design. The data of CBR value and its grading properties of soil were collected from a number of samples in UiTM Shah Alam, Malaysia. The laboratory tests were carried out to compare with the published correlation for CBR value and the grading properties of soil.
1.5 Significance of the Study
The study will help engineer to predict and give some idea of the value of CBR based on known the grading characteristic of the soil. By this way, it will help the engineer to choose the best material for their project and improve the quality of the highway and pavement structure in Malaysia. Without carried out the CBR test, the engineer can save a lot of time and also can cut the cost of the project.
This chapter will cover about the theoretical review on the soil classification, Soil grading properties and California Bearing Ratio (CBR). It also reviewed some of the researches that have been conducted which related to correlation between CBR value and grading properties of the soil.
2.2 Soil Classification
Soil classification is compulsory for the proposed of describing the various materials in the site exploration to proceed with design stage. Without the use of classification system, it will lead for misleading and it will difficult to fain future design or recommendation on design and material used in the construction. Theoretically, soils classification will divide into three main categories; Coarse, Fine and Organic as tabulated below;
Table 2.1 Major Classes of engineering soils (Roy Whitlow)
Inclusive soil types
Rounded to angular
Particle or grain size
Porosity or void ratio
Low to very low
None to very low
None to Low
Low to high
Low to moderate
Moderate to very high
Rate of compressibility
Moderate to slow
Moderate to rapid
For the purpose of identification and classification in the field a series of simple test may be carried out such as particle size distribution or grading properties that will be the focus for this study.
2.2.1 Particle size Distribution (Grading)
The Grading of the soils refers to the distribution of sizes; a well-graded soil has a wide distribution of particle size while poorly graded or uniform soils contain only a narrow range of sizes. Grading can be done either by rapid estimate using field settling test, uses sieve analysis and hydrometer (sedimentation Test) based on soil characteristic either cohesionless or soils or cohesive soils.
188.8.131.52 Field Settling test
Field Settling test can be done on both cohesionless and cohesive soil using a tall jar or a bottle. A sample of soils is soaking and filled with water then the bottle need to be shakes till the soil seems homogeneous. Let the sample to settle by gravity for a couple of minutes. The heavier particles will settle faster than smaller particles. The percentage of particle size can be measured by layer of the settle.
184.108.40.206 Sieve Analysis Test
For sieve analysis test, it only used for cohesionless soil or coarse-grained soils. Generally, grading is the screening process using a series of U.S Standard Sieves Number. The distribution is determine by passing the sample trough a nest of standard test sieves arranged in descending order of mesh size. In Malaysia, the British Soil Classification System (BSCS) indicated in BS 5930 (1999) has been widely used by engineers in classifying the soils. The soils are classified into groups according to size, and the groups are then further divided into coarse, medium and fine sub-groups.
The particles are classified as Coarse if the particles sizes are 65 % greater than 0.06mm for example it is sand or gravel. Otherwise if the distribution is 35% are less than 0.06mm, it is a fine soil such as silt and clay. The definition of soils is classified by grading according to BSCS as Table 2.2.
Table 2.2 British Standard range of particles sizes
1 2 6 20 60 200 600 2 6 20 60 200
The cumulative percentage quantities finer of certain sizes that passing a given size sieve mesh are determined by weighing. Points are then plotted of % finer (passing) versus log size. A smooth S-shaped curve drawn through these points is called a grading curve. The position and shape of the grading curve determines the soil class. Geometrical grading characteristics can be determined also from the grading curve.
Figure 2.1 Grading curve
Based on the plot, the following characteristics are determined in order to classify the soil:-
Effective size = D10
Uniformity Coefficient, Cu=D60/D10
Coefficient of Gradation, Cg=(D30)2 / (D10 x D60)
(C u < 3 is uniformly graded whereas Cu > 3 is well graded)
(Cg ranging between 0.5 to 2.0 to confirm as well graded soil)
But for the typical grading curve, both the position and the shape of the grading curve for a soil can aid its identity and description. Some typical grading curves are shown in the figure 2.2:
A -a poorly-graded medium SAND
B - a well-graded GRAVEL-SAND
C - a gap-graded COBBLES-SAND
D - a sandy SILT
E - a typical Silty CLAY
Figure 2.2 Typical grading curves
Figure 2.3 Particle size distribution apparatus
Figure 2.4 Series of U.S Standard Sieves
220.127.116.11 Hydrometer Test
Hydrometer test is based on the principles of sedimentation of soil grained in water. Distribution of soil particles having sizes less than 75 micron (Fine Grained soils) is often determined by a sedimentation process using a hydrometer to obtain the necessary data such as the borderline between clay and silt. Using this test the grain size distribution for soils containing appreciable amount of fines is obtained. Properties of fine soils are highly dependent upon the fractions of clay and other components.
A sphere falling freely through a liquid of inifite extent will accelerate rapidly to a certain maximum velocity and will continue at that velocity as long as conditions remain the same. The relationship of the terminal velocity to the physical properties of the sphere and the liquid are expressed by Stoke's Equation as follows (Whitlow 2004):
V = [(Î³S - Î³w) / 18Âµ ] D2
Where:- V = Terminal Velocity
Î³S = Unit Weight of sphere
Î³w = Unit Weight of Liquid
Âµ = viscosity of liquid
D = diameter of sphere
2.3 California Bearing Ratio
California bearing Ratio is defined as the ratio between the force required on test soil and force required for same penetration on standard soil. The method was developed by the California Division of Highways in 1930s as part of their study in pavement failure. The test procedure is fully detailed in BS1377 and is required for design procedure such as road and airfield to develop and evaluate the strength of road subgrades. The results obtained by these tests are used with the empirical curves to determine the thickness of pavement and its component layers. This is the most widely used method for the design of flexible pavement.
The method of evaluating CBR is standardized in ASTM D1883 and BS1377-4:1990. The test is an index test, thus it is not a direct measure of stiffness modulus or shear strength. The ratio provides a means of comparison between the strength of subgrade and the standard crushed stone base kept in California Division of Highways laboratory. CBR test is frequently used as an index test to evaluate the strength of road subgrade as direct determination of stiffness modulus and shear strength difficult. This strength value is often used as a guide to the design of road pavement thickness or to assess compliance of subgrade against minimum specification values set by the design engineer.
This test is important to determine the stability of the structure that related to the bearing capacity. A soil with insufficient bearing capacity to support the loads applied to it may simply fail by shear, allowing the structure to move or sink into the ground. Such a soil may fail because it undergoes excessive deformation, with consequent damage to the structure. Sometimes the ability of a soil to support loads is simply called its stability. Bearing capacity is directly related to the allowable load that may be safely placed on a soil. This allowable load is sometimes called the allowable soil pressure.
2.3.1 Application of California Bearing Ratio. (Carter and Bentley, 1991)
The main application of California Bearing Ratio (CBR) is to evaluate the stiffness modulus and shear strength of subrade. Generally, the subgrade soil cannot bear the construction and commercial traffic without any distress, therefore; a layer of rigid or flexible pavement is required to be laid on top of the subgrade to carry the traffic load.
The determination of the thickness of the pavement layer is governed by the strength of subgrade, thus the information on stiffness modulus and shear strength of subgrade are required before any pavement design is carried out. These parameters are necessary to determine the thickness of the overlaying pavement n order to achieve optimum and economic design. This stiffness modulus and shear strength of subgrade is controlled by particularly plasticity, soil type, density, degree of remoulding and effective stress (The Highway Agency, 1994). The effective stress is dependent on the stress from the overlying soil layers, the stress history and the suction. In turn, suction is depends on the moisture content history, soil types and depth of water table.
Due to the number of factors that make the measurement of stiffness modulus and shear strength of subgrade complicated, it is necessary to adopt a more simplified test method that can be used as an index test. The CBR test is a simple strength test that compares the bearing capacity of a material with that of a well graded standard crushed stone base material. This means that the standard crushed stone material should have a CBR value of 100%. The resistance of the crushed stone under standardized conditions is well established. Therefore, the purpose of a CBR test is to determine the relative resistance of the subgrade material under the same conditions.
If the CBR value of subgrade is high, it means that the subgrade is strong. Accordingly, the design of pavement thickness can be reduced in conjunction with the stronger subgrade. Thus it will give a considerable cost saving in term of construction besides an optimum design. However, if the CBR value of subgrade is weak with low CBR value, the thickness of pavement shall be increased in order to spread the traffic load over a greater area of the weak subgrade. This is important to prevent the weak subgrade material to deform excessively and causing the road pavement fail.
Alternatively, the easiest method to overcome this weak subgrade before the construction of pavement is by replacing the soil with adequately compacted soil in layers. Otherwise, the subgrade can be stabilized by lime, cement, or the use of a geotextile to produce a stable platform for construction equipment and traffic load in long term. The CBR test is used exclusively n conjunction with pavement design methods and the method of sample preparation and testing must relate to the assumptions made in the design method as well as to assumed site conditions. For instance, the design may assume that soaked CBR value are always used, regardless of actual site conditions. (Carter and Bentley, 1991)
Figure 2.5 EL25-3700 series Multiplex 50 with Accessories
Figure 2.6 ASTM Mould and Accessories
Figure 2.7 BS/EN Mould and Accessories
2.4 Correlation between CBR and Grading Properties of Soils
The value of California Bearing Ratio (CBR) can be related with the physical properties of soils such as grading properties that maybe vary from difference location of soil. There are some of researcher that already correlate the CBR value with other properties such as British Highways Agency 1994 and National Cooperative Highway Research Program (2001).
2.4.1 Design Manual for Roads and Bridges (British Highways Agency 1994)
The Highway Agency (1994) had proposed an estimation of CBR values based on plasticity index for British soils compacted at natural moisture content which is shown in Table 2.3. The precise density and moisture content conditions corresponding to the predicted CBR values are not specified. As such, this table shall be limited for the use of British soils only. Furthermore, the predicted CBR values as stated in this table do not take into the account of water table depth below subgrade formation level.
As shown in the table, it can be observed that the soil types play the most important role in determination of CBR values. Predicted CBR values of 20% to 60% can be obtained from coarse-grained soil whereas for fine-grained soils CBR values in the range of 2% to 5% are expected. Therefore, cohesionless soils can provide higher CBR values compared with cohesive soils.
Table 2.3: Subgrade CBR estimation of British soils compacted at natural moisture
Content (The Highway Agency, 1994)
TYPE OF SOIL
PLASTICITY INDEX (%)
PREDICTED CBR (%)
2 to 3
3 to 4
4 to 5
4 to 5
Sandy (Poorly Graded)
Sandy Gravel (Well-graded)
Soil grading characteristics is also one of the factors that affecting the CBR values. Poorly graded sand shows predicted CBR of 20% while well graded sand give CBR value as high as 40%. This indirectly confirms that the relative density of soils is essential in determination of CBR values.
It is worth to note that plasticity index has impact on the predicted CBR values as shown in the Table 2.3. The predicted CBR values of 2% to 5% were obtained from soil with plasticity index ranging from 10% to 70%. Hence, it shows that CBR values can be correlated with soil plasticity.
CBR values depend not only on soil index properties but also on the density, moisture content, and to some extent, method of sample preparation during laboratory testing. These factors must therefore be taken into account when considering correlations between CBR and soil classification tests.
2.4.2 National Cooperative Highway Research Program (2001)
National Cooperative Highway Research Program (2001) of United States of America through the "Guide for Mechanical-Empirical Design of New and Rehabilitated Pavement Structures" had developed some correlations that describe the relationship between soil index properties and CBR values. Two equations were established where one was for non-plastic coarse-grained material and the other was for soils which contains 12% fines and exhibit some plasticity.
The best-fitted equation proposed by NCHRP for clean, coarse-grained soil is shown as below;
CBR = 28.09(D60)0.358 (EQ.2.1)
Where; D60 = Diameter at 60% passing from grain size distribution
(Unit in millimeter)
Equation above is limited to D60 values greater than 0.01mm and less than 30mm. For D60 less than 0.01mm, the recommended value of CBR is 5% whereas CBR value of 95% is recommended for D60 greater than 30mm.
For plastic, fine-grained soils, the soil index properties chosen to correlate CBR are the percentage passing No.200 U.S. sieve or 0.075mm size sieve and plasticity index. The suggested equation by NCHRP is shown below.
CBR = 75 / [1+0.728(wPI)] (EQ.2.2)
Where; w = Percentage passing No.200 U.S sieve (in decimal)
PI = Plasticity Index
2.4.3 de Graft - Johnson and Bhatia (1969)
A correlation of CBR with plasticity and grading using the concept of suitably index was developed by de Graft-Johnson and Bhatia (1969). The correlation is shown as below and Figure 2.8 In this case, the suitability index is defined as:
Suitability Index= A / LL log (PI) (EQ2.3)
Where: A = Percentage passing 2.4mm BS sieve
LL = Liquid Limit
PI = Plasticity Index
It is worth to note that the soil samples were compacted to maximum dry density at optimum moisture content and soaked for 4 days according to the Ghana standard of compaction. This specifies the use of a standard CBR mould and a 4.5kg rammer with 450mm drop height to compact the soil in 5 layers using 25 blows per layer.
Figure 2.8: Relationship between suitability index and soaked CBR values
For this chapter, it will cover the methodology and procedure on how the test will be done either in the lab or in situ test. The Theoretical part already been detailed in the literature review in chapter 2. Literature review briefly discuss the test involve in this study for both CBR test and grading characteristic test either sieving analysis or hydrometer test. It also contain of current researched from other party related to this correlation between CBR and grading characteristic take taken from the journal, internet and other resources.
For this study, data for CBR test and grading characteristic of soils were collected from a number of locations in UiTM Shah Alam, Malaysia. The sample of soils is brought to the laboratory to obtain the parameter required for this study. The data obtain for CBR and grading characteristic are simulate and correlate to each other to publish the correlation between CBR and grading properties as indicated in the objective for this study. The overall methodology is visualized in the Figure 3.1.
3.2 Data Collection
3.2.1 Soils Sample
The samples are collected in three different locations within UiTM Shah Alam Area to test for this correlation between CBR test and Grading Characteristic. The sample taken should be collected using appropriate procedure to avoid disturbance of the original soils strength and characteristic. The sample will be test to determine the soil particle characteristic by performed in laboratory by hydrometer test or sieving analysis depending on the soil particle size that suited the test. The sample also will be test by CBR test to achieve the objective of obtaining the correlation between the CBR test and Grading Characteristic
Literature Review Study
Collection of Sample
Analysis of Result
Compile and correlate data
Publish Correlation between CBR and grading characteristic
Figure 3.1 Overall methodologies
3.2.2 Preparation of Sample
The sample for this study should consider the condition and the original content of the sample. There are two type of sample that is undisturbed sample and disturbed sample. Both samples maybe vary for their characteristic, basic properties and quality. We can have both samples by using appropriate method to sampling the sample.
18.104.22.168 Disturbed sample
Disturbed sample can be obtained by method of sampling such as by drilling or digs process where it may cause the disturbance to the soils condition and moisture content. For this study, a tools such as hoe, scoop, and plastic bag can be used to done the digs process. It is easier than drilling process that required a drill or other suitable equipment to do it. The sample is taken using a scoop and put into the plastic bag then the plastic bag is ties tightly in order to preserve remaining moisture content and its original condition. Disturbed sample are suitable to be used in grading test for my study.
22.214.171.124 Undisturbed sample
Undisturbed sample is the sample which the structure and water content preserved and almost same with the site condition. In order to get the best result of undisturbed sample, a suitable coring method presented. The tools used in this coring method are hand auger, wrapping plastic, knife, hammer, newspapers and sampler. The top layer of the soils will be removed using hand auger approximately 1m from ground level. Then the sampler is being inserted and knocks with hammer until it fill with the soils. Then it being pulls out from the core and wrapped with plastic to preserve the water content of the sample. The wrapped sample should be rewrapped by using newspaper to keep the best condition from other defect.
3.2.3 Data Analysis
The data obtain from this study will be tabulated and plotted in a graphical method to achieve the objective for this study for publishing a correlation between CBR and grading characteristic. The data was stimulated in Microsoft Excel and other type of software to visualize the data in graphically view by plotting the both data on a same place simultaneously.
For this study, graphical models will be used in the analysis is Polygram for referring to line graph relating two or more variables. This model will be adopted when carrying out evaluation on the existing established CBR correlations with grading characteristic. CBR values and grading characteristic will be plotted and compared with the lines generated from the existing CBR correlations.
Subsequently, an equation can be established based on the correlation developed. This method is not an experimental but it is a mathematical technique for summarize the data that corresponding to one or more variables. Correlation developed will be used as a basis for prediction. Therefore, this method will be adopted to find the new CBR correlation with grading characteristic that best suited the type of soil in UiTM Shah Alam, Malaysia.
3.3 Laboratory Testing
3.3.1 California Bearing Ratio Test
CBR test is to determine the relationship between force and penetration when a cylindrical plunger of a standard cross-sectional area is made to penetrate the soil at a given rate. At certain values of penetration ratio of the applied force to a standard force, expressed as percentage, is defined as the California Bearing Ratio
20mm BS test sieve
A balance capable of weighing up to 25kg readable and accurate to 5g.
A cylinder CBR moulds having an internal diameter of 25mm and an internal effective height of 127mm with detachable base plate and a collar of 50mm deep.
Wooden hammer or rubble mallet
4.5kg metal hammer
Apparatus for moisture content determination.
CBR machine for applying the test forces through the plunger, consisting of a force measuring device and means for applying the forces at a controlled rate
Place the mould with base plate containing the sample, with the top face of the sample exposed, centrally on the lower platen of the testing machine.
Place the appropriate annular surcharge discs on top of the sample.
Fit it into place the cylindrical plunger and force-measuring device assembly with the face of the plunger resting on the surface of the sample.
Apply a seating force to the plunger, depending on the expected CBR value, as follows,
For CBR value up to 5% apply 10 N
For CBR value from 5% to 30%, apply 50 N
For CBR value above 30% apply 250 N
Record the reading of the force-measuring device as the initial zero reading.
Secure the penetration dial gauge in position. Record its initial zero reading.
Start the test so that the plunger penetrates the sample at a uniform rate of 1 Â± 0.2mm/min, and at the same instant start timer.
Record the readings of the force gauge at the intervals of penetration of 0.25 mm, to a total penetration not exceeding 7.5 mm
Carry out the test on base by repeating all the above procedures
3.3.2 Sieving analysis Test
For this study, a disturbed sample from 3 locations in UiTM Shah Alam are used in order to do this sieve analysis test to obtain the soil classification based on grading characteristic for dry sample. The sample will be put in the oven for about 24hours before proceed to sieve analysis testing.
Dry sieving test is usually done when there is less or no fine grained soil particles present in the soils sample. The procedure for done the dry sieving will be:-
The sample will be dried in a oven for about 24hours.
The sieves set is cleaned by brushing the sieve set using wire brush.
An empty sieve set is being weighed and the mass recorded.
A sample of 0.5kg used to each test as indicated in BS1377 Table 1.
The sieve set is arranged according from larger size to smallest size and being placed on the sieve shaker machine.
The sample is put on the top sieve set and closed the set with cover.
The Sieve is set for 15minutes and started.
After 15minutes, the sieve set is weighed one by one starting from the top sieve to bottom and the result is recorded.
The result obtain in this test are tabulated and the grading curve is plotted to determine the grading characteristic.
3.3.3 Hydrometer Test
Hydrometer test also called as wet sieving so it can measure the sample which is contain such fined grained particles to determine the combined clay/ silt fraction percentage. The expected procedure for this test is:-
Weight the oven dried sample to 0.1% of its mass, m1. Place the sample on the 20mm test sieve and any particles that too coarse to pass through the test sieve will be brush out with wire brush or similar stiff brush until the individual particles are clean from any finer materials. Precaution should be taken when dealing with soft material do avoid the large particles to be remove its parts.
Sieve the fraction retained on the 20mm test sieve on the appropriate larger test sieves and the amount of retained on each sieve are recoded. The weight of each pan not to exceed the maximum masses as indicated in Table 3.1 accordingly to BS 1377:1990.
Weigh the portion of oven dried material passing 20mm test sieve to 0.1% of its total mass, m2. Riffle that portion so that a fraction of convenient mass (about 2kg) is obtained. Weigh the fraction to 0.1 of its total mass, m3.
Spread the riffled fraction in the large tray, or place it in the bucket and cover with water. If the soil is cohesive, add sodium hexametaphosphate to the water first at a concentration of 2g/L.
Stir the mixture well to wet the soil. Allow the soil to stand for at least 1hr in this solution stirring frequently.
Wash the material, a little at a time through a 2mm test sieve nested in a 63Âµm test sieve, allowing the material passing the 63Âµm test sieve is virtually clear. Ensure that neither the test sieve is overloaded in the process: either with solids or with water in Table 3.1. The maximum amount of material initially on the 63 Âµm test sieve shall not exceed 150g for a 2000mm diameter test sieve, 350g for a 300mm diameter test sieve or 750g for a 450mm diameter test sieve.
Transfer all the material retained on the sieved into tray or evaporating dish and dry in an oven at 105 °C to 110 °C.
Weigh the dried fraction when cool to 0.1% of its total mass, m4. Sieve the dried fraction through the appropriate sieves down to the 6.3mm test sieve, using dry sieving procedure. Weigh the amount retained on each sieve to 0.1 % of the total dry fraction.
If the fraction passing the 6.3mm test is small, i.e. not more than 150g, the sample may be sieved by dry sieving on the appropriate sieve to and including the 63mm test sieve. Weigh the amount retained on each sieve and any fines passing the 63mm test sieve, mf to0.1% of the total fraction passing the 63mm sieve.
If the fraction passing the 6.3mm test sieve is large, i.e. substantially greater than 150g weigh it (mS) and then riffle it so that a fraction of 100g to 150g is obtained. Weight the fraction, m6 and the sieve on the appropriate sieves down to and including 63mm test sieve, mE. If the riffling is not necessary, m6 is the same as m5. Weigh to 0.1% if the total fraction passing the 63mm sieve.
Figure 3.2: Riffle Box
Figure 3.3: Hydrometer Test Apparatus
Table 3.1 Maximum mass on sieve of diameter, (BS1733:1990)
Maximum mass on sieve of diameter
There are some probability can be expected for this research since the purpose sample taken at UiTM Shah Alam, which are the soil may be vary from its location. UiTM soils may exist a cohesive and also cohesion less soil. It is also maybe vary for their basic properties such as water content and plasticity index.
On gradation process, it resulted from two types of sieving test which are dry grading by using sieve analysis while wet grading by using hydrometer. It means that tow types expected result from gradation process will be clay, silt sand or gravel. These types of soil are expected from both experiments to determine the details grading characteristic which are well graded, poorly graded and uniformly graded.
Predicted outcome from California Bearing Ratio test will be a percentage ratio and maybe different which dependent on the type of soil related to the soil classification that comes from the grading process. For this study, a correlation will be publish when both result on grading process and CBR test plotted on a same graph hence a equation also maybe can be obtain to correlate both data.