Prediction of the Dynamic Modulus of Granular Crumb Rubber Modified Asphalt Concrete based on Micromechanics

摘要

Dynamic modulus (|E*|) of asphalt mixture is widely used as an important material property in mechanistic-empirical (ME) pavement analysis and design. Although direct laboratory tests provide the ways to obtain the values of dynamic modulus of granular crumb rubber modified asphalt concrete (GCRMAC), a predictive model based on the microstructure of GCRMAC is more desirable. This study presents a viscoelastic micromechanical model to predict the dynamic modulus of GCRMAC from existing two-phase and three-phase micromechanical models. The dynamic modulus of GCRMAC is established on basis of micromechanical theory for effective modulus of the composite and the elastic-viscoelastic correspondence principle. Then the dynamic modulus equations of GCRMAC is derived from the proposed model and the equations are able to take into account the viscoelastic effect of asphalt concrete and crumb rubber fraction. Laboratory tests are conducted to verify the efficacy of the model in predicting the dynamic modulus of GCRMAC. The results show that a discrepancy exists between the predicted and measured dynamic modulus. The reasons for the discrepancy between measured and predicted results and the factors affecting the dynamic modulus are also explored in this study.