A Review on Factors Affecting the Resilient Modulus of Subgrade Soils

Abstract

The subgrade layer is the lowest pavement layer, which carries the loads transferred from the upper layers. Different researchers have studied the resilient modulus (Mr) of different subgrade soils for the fine-grained and coarse-grained soil types. The layer's resilient response mechanism was found to be different for those fine and coarse materials, and it is vital for improving the pavement performance and life constructed over it. The different parameters related to the soil that can affect the resilient modulus include moisture content, stress level, compaction degree, loading frequency, and matric suction characteristics. Due to the variability of the Mr result, a study is needed for each soil type and input parameter. The effects of these parameters on the Mr are reviewed and discussed in this paper. The results show that the water content beyond the optimum level and the increase in deviatoric stress decreased Mr. In contrast, the increase in confining stress, compaction degree, loading frequency, and matric suction was found to improve the Mr. During the wetting and drying of the soil, the Mr was improved in the drying process.