Estimation of Resilient Modulus for Fine-Grained Soils Using Ground Penetrating Radar

Abstract

As state Departments of Transportation (DOT) continue to adopt the Mechanistic-Empirical Pavement Design Guide (MEPDG), the ability to readily obtain higher quality input parameters becomes an ever-growing need. One such parameter is the Resilient Modulus (MR), which is defined as the ratio of cyclic deviatoric stress to recoverable strain. The ensuing investigation was conducted in an attempt to replace the use of the repeated load triaxial test in determining the MR of soils with modulus estimations obtained from Light Weight Deflectometer (LWD) and Ground Penetrating Radar (GPR) testing. The constructed test setup consisted of a test pit subdivided into six sections containing an elastic silt (MH) at different water content and density levels. LWD and GPR testing was conducted at each of the six test sections, and the results were correlated to the different soil water content and density levels. Through a regression analysis, the preliminary model was developed the ELWD of fine-grained soils was estimated using the soil’s water content, bulk density, and the measured dielectric constant. A strong correlation was observed (R2 of 0.858) between the predicted and measured ELWD values, indicating its potential for future use in predicting stiffness of fine-grained soils using GPR.