A Rational Approach for Estimating the Resilient Modulus of Constructed Granular Subgrade Materials

The resilient modulus is an essential engineering property for determining the stress-strain characteristics of pavement structures subjected to traffic loadings. Due to the complexity, labor intensiveness, and time consuming in conducting resilient modulus measurements in laboratory, it is necessary to establish a rational approach for estimating the resilient modulus of subgrade materials after compaction. This paper presents an extensive study to estimate the resilient modulus from basic soil properties for two common types of granular subgrade soil in Florida: fine sand (A-3 soil), and silty/clayey sand (A-2-4 soil). Laboratory triaxial tests were conducted to measure the resilient modulus values of constructed granular subgrades at different conditions. Correlation models were developed for different types of soil from experimental results. The estimated resilient modulus values from the correlation models were generally within a range of +/- 20% of the measured resilient modulus values from laboratory triaxial tests. This approach for estimating the resilient modulus of subgrades could be utilized in the mechanistic-empirical pavement design guide to better evaluate the resilient modulus of constructed subgrade materials.