Investigation into fatigue life of interface bond between asphalt concrete layers

A proper interface bond between adjacent asphalt concrete layers ensures the layers to act monolithically to withstand traffic and thermal loading. The presence of a weak interface results in delamination, slippage and fatigue cracks thereby affects the pavement performance; hence, requires careful evaluation. The objectives of this investigation are three-fold. The first objective is to develop a test protocol to investigate the damage characteristics of the interface bond. The proposed test applies a 5 Hz cyclic shear load on a double-layered asphalt concrete specimen using a Modified Advanced Shear Tester at 23°C. The second objective is to determine the effect of interlayer shear modulus on the pavement response of typical pavement sections using numerical simulations. The interface material model property used in this study is a set of arbitrary values that lies within the typical range of interlayer shear modulus values observed during cyclic shear tests. The third objective is to propose a failure criterion for shear fatigue testing that is based on the critical tensile strain obtained during pavement response analysis. The test outcomes show that specimens with a tack coat at the interface exhibit a significant increase in shear fatigue life resistance compared to specimens with no tack coat.