Evaluation of resilient modulus and unconfined compressive strength of subgrade

Subgrade soil is the important material as the foundation for supporting the pavement layers and the repeated load of vehicle traffic. To characterize the stiffness and strength behavior of subgrade due to traffic loading in structural pavement design can be determined by resilient modulus and unconfined compressive strength test. In this study, laboratory test of resilient modulus and unconfined compressive strength used to investigate (1) the effect of moisture content of the changes of stiffness and strength characteristics, (2) the correlation between the resilient modulus and elasticity modulus. The soil sample prepared at five type of compacted soils, at the dry side (OMC-20%OMC and OMC-10%OMC), OMC and at the wet side (OMC+10%OMC and OMC+20%OMC) . The result shows the moisture content has a significant effect on cohesive soil, the resilient modulus, modulus elasticity and stress value increase with the increase of moisture content until reaching the optimum moisture content (OMC) and then decrease with the increase of moisture content on the wet side of OMC point. By comparing both resilient modulus and unconfined compressive strength result from ANOVA statistics analysis can be concluded that there is no difference in stiffness between resilient modulus and modulus elasticity methods.