Resilient Modulus of Fine-Grained Soils for Mechanistic–Empirical Pavement Design

The research objectives were to establish a resilient modulus test result database and to develop correlations for estimating the resilient modulus of Wisconsin fine-grained soils from basic soil properties. Laboratory testing was conducted on representative Wisconsin fine-grained soils to evaluate their physical and compaction properties. The resilient modulus of each investigated soil was determined from the repeated load triaxial (RLT) test according to the AASHTO T307 procedure. The laboratory testing program produced a high-quality, consistent database of test results. The resilient modulus constitutive equation of mechanistic–empirical pavement design was selected to estimate the resilient modulus of Wisconsin fine-grained soils. Material parameters of the constitutive equation were evaluated from RLT test results. Then statistical analysis was performed to develop correlations between basic soil properties and constitutive model parameters. The resilient modulus values obtained from RLT tests and estimated from the constitutive equations were in agreement. The correlations developed could estimate the resilient modulus of compacted subgrade soils with reasonable accuracy. The proposed material parameter correlations could be used to estimate the resilient modulus of Wisconsin fine-grained soils as Level 2 input parameters. Statistical analysis of the test results also provided resilient modulus values for the investigated soil types that can be used as Level 3 input parameters.