Evaluating the rutting resistance of asphalt mixtures using a simplified triaxial repeated load test

A Simplified Triaxial Repeated Load Test (STRT) is reported to evaluate the rutting resistance of asphalt mixtures under field conditions. The laboratory tests and field measurements are conducted to verify the feasibility of the newly developed test method to characterize the permanent deformation of asphalt mixtures. The sensitivity of D1, λ (regression parameters in the Stephen Price model) and flow number FN measured by conventional Triaxial Repeated Load Test (TRT) and STRT is compared. Then the correlations between D1, FN and the rutting depth of a selected asphalt pavement are analyzed. The results indicate that the varying confinement in the STRT has significant effects on the permanent deformation of asphalt mixture. Repetitive tests prove that parameters measured by STRT share the similar stability with TRT. D1 can be used as an alternative indicator to assess the rutting resistance of mixtures, particularly for the polymer modified asphalt mixtures. D1 and FN measured by both STRT and TRT have good relevance with the rutting depth of the asphalt pavement, while the STRT makes a better distinction of permanent deformation between field cores with different rutting depths. As a result, the newly developed STRT turns out to be feasible and can better understand the dynamic creep properties of asphalt mixtures.