Evaluation of resilient behavior of flexible pavement asphalt layers

Abstract

Asphalt concrete is a viscoelastic material that has a resilient behavior during cyclic loads. One of the important features for defining this behavior is resilient modulus (MR). Usually, asphalt mixture is laid down in two layers known as binder and surface layers at different depth beneath the road surface. The current test methods use only one loading pulse shape, namely, haversine that represents the shape of loading exerted to the binder layer. Thus, this paper investigates resilient behavior of asphalt material in different depths. Indirect tensile test was employed for determination of MR using universal testing machine. The modulus of asphalt mixture was measured by applying the two pulse shapes in a range of temperatures and pulse widths. The pulse shapes were haversine and square, describing the behavior of mixture in binder and surface layers, respectively. The test results showed that difference between resilient behavior of binder and surface layers is more apparent at high temperatures and under fast traffic loadings. In addition, using the best-fitted functions to MR results and mathematical calculations, haversine pulse widths for surface layer were specified. The MR testing under haversine pulse should be performed with longer pulse widths compared to square loading to fulfill resilient behavior of surface layer accurately. The MR test under haversine pulse was more accurate and beneficial than square one.