Development of a Repeated Load Deformation Test Simulating Moving Loads on Asphalt Concrete

Abstract

Asphalt concrete (AC) layers in highway pavements are subjected to complex three-dimensional (3D) stress states due to moving load and maneuvering effects of heavy trucks in highway pavements. This paper aims to investigate and characterize the impact of moving load by simulating different scenarios of truck platoons (spacing) on the permanent deformation of AC mixture at various depths within the AC layer. An experimental program was developed using novel design triaxial testing equipment to induce moving load stress states. A custom-designed dynamic pulse configuration was developed by independently applying axial and horizontal stresses in both directions. With the individual pulsing in axial and horizontal directions, stress states simulating platoon moving loads can be compared with conventional flow number experiments with dynamic axial pulsing with constant confinement pressure. The experimental plan includes two mix designs [i.e., fine-dense graded and stone matrix asphalt (SMA) with binder type (PG 76-22SBS), temperature of (54.4°C)], and different rest periods simulating different truck platoons space configurations. Different advanced tests were performed to characterize the permanent deformation and predict rutting in the AC layer using FlexPave software. The results showed that the dynamic multiaxial moving load test exhibited higher permanent deformations than the conventional tests. Furthermore, the results indicated that increasing loading time reduced the effect of rest periods. Additionally, the rutting predicted model (FlexPave) using different structural layers showed that increasing rest periods increased permanent deformation.