Evaluation of resilient modulus constitutive equations for unbound coarse materials

•Resilient modulus of base and subbase material.•Regression constants of constitutive equations.•Deformation measurement with internal and external LVDT. This paper presents the evaluation of some of the most commonly used constitutive equations related to the resilient modulus of unbound aggregates. In this study, the resilient modulus of 18 different aggregate base and subbase materials were measured in the laboratory by following AASHTO T-307. Four different constitutive models including K-θ Model, Uzan Model, Modified Uzan Model, and AASHTO recommended MEPDG model were evaluated for the selected test aggregates. The model parameters (e.g., ki parameters) were obtained through multiple regression analysis by using the resilient modulus data. The regressed coefficients of the equations were evaluated and comparable results were achieved while comparing to other available values in the literature. All four selected models performed well for the selected aggregates and most of the goodness of fit (R2) were found more than 0.90.