An Evaluation of the Stress Non-Uniformity Due to the Heterogeneity of AC in the Indirect Tensile Test

Simple Performance Tests (SPT) including Indirect Tensile (IDT) Test and Dynamic Modulus Test have been widely used in the evaluation of the performance of asphalt concrete. The so-called SPT tests typically apply uniform stresses on the boundary and therefore obtain the stress-strain relation with convenience. Nevertheless, asphalt concrete is a heterogeneous material composed of asphalt binder, aggregates and air voids. The three constituents have drastically different stiffness. Even under a uniform boundary stress, the internal stress and strain distributions are not uniform. This paper presents a comparison between the stress distribution based on heterogeneous material properties and that based on homogeneous material properties using X-ray Computed Tomography (XCT) and Finite Element (FE) simulation. The comparison indicates that material heterogeneity is an important factor that must be considered in the characterization of asphalt concrete.