Effects of using different dynamic moduli on predicted asphalt pavement responses in mechanistic pavement design

In this study, dynamic moduli of asphalt mixtures under uniaxial compression (UC), indirect tension (IDT) and four-point bending (4PB) loading modes were tested and incorporated in the MEPDG procedure to predict the pavement responses. The field responses from a full-scale asphalt pavement were used to evaluate the prediction accuracies of three types of moduli. It was found that the current MEPDG procedure using UC modulus underestimates the strain responses of the pavement. Alternatively, the use of 4PB modulus in the MEPDG generates accurate strain predictions at the intermediate temperatures, but not at high temperatures. The combined use of UC modulus and the adjusted loading frequency, f′=1/(2πt) also generates accurate strain predictions at the intermediate temperatures. At high temperatures, the combined use of the 4PB modulus and f′=1/(2πt) was found to generate the most accurate prediction results. Accurate prediction of asphalt pavement responses is apparently dependent on the proper selection of modulus type and loading frequency.