CBR has also been correlated empirically with resilient modulus and a variety of . of static load tests by no means bear a simple relation to pavement behavior. knowledge of the resilient modulus of pavement layer materials allows determination of how . the relationship between resilient modulus and stress state. .. common correlation equation using CBR is shown in Equation There are many different correlation equations between CBR, R-value and resilient modulus. Each one has its limitations, which should be headed. Table 2 .
At certain values of penetration ratio of the applied force to a standard force, expressed as percentage. The test is fully covered in BS Soils for civil engineering purposes: Part 4, Compaction Related Tests.
CBR Test Figure 2: The machine includes loading frame and software that controls the materials dynamic test. The geotechnical properties of the soil before adding the additives are shown as in Table 1.
Properties of Soil before Stabilization. The gain in CBR values are depended on the amount of water content and fly ash in the sample. The mean for 28 days of curing is slightly higher compared to mean on 7 days of curing. Contrarily as for California Bearing Ratio CBRit can be conclude that there are no statistically significant differences between 7 days of curing and 28 days of curing since the p-value is more than 0.
Therefore, the overall data for 7 days and 28 days of curing was also found to be moderately positive where the p-value is 0.
For t-test analysis, MR analysis for p-value is 0. Therefore, an attempt has been made to find the Resilient Modulus and CBR rating of the sand at different relative densities and also attempted to correlate the findings of a laboratory measurement of Resilient Modulus and to its CBR rating.
Specimens are prepared at the relative densities ranging from loose to dense state. The concept of Resilient Modulus MR was initially introduced by seed et al.
It is defined as the ratio of the repeatedly applied load stress to the recoverable strain determined after repeated loading. It can be seen that both elastic and plastic deformations occur at the initial stage of load application. As the number of load application increases, the amount of plastic deformation decreases until a stage where the deformation is practically all recoverable. This test provides an indirect measure of shear strength of soil.
The CBR number or, simply the, CBR is obtained as the ratio of the unit stress required to effect a certain depth of penetration of a compacted specimen of soil to the unit stress required to obtain the same depth of penetration on a standard sample of crushed stone.
For most fine grained soil, MR decrease with increasing deviatoric stress level. The cyclic Odeometer test and CBR test is carried out at different relative densities. Direct shear is also done to study the behaviour of shearing angle according to relative densities.
Figure 3 shows the grain size analysis data of Trishuli River sand. The soil can be described as uniform sand according to the USCS.
The specific gravity of the soil was equal to 2. The testing program was conducted on air dried sample. This procedure deviates from the conventional CBR testing procedure in which the tests are conducted only at optimum moisture contents. Direct shear test is carried out to study the variation of shearing angle according to the relative density.
The value of shearing angle varies from 34 to Then variation of shear angle with relative density is shown in figure 4. It is shown that as the relative density increases, the hysteretic loop is closed at lesser strain.