Axial dynamic test in notched cylindrical specimen to measure fatigue behavior in asphalt mixtures

Abstract

Fatigue cracking is one of the most common damage mechanisms on the pavement structures. This phenomenon is associated to the damage produced by repetitive load application, whose load magnitude is lower than the maximum admissible resistance that the material may resist. Because of this, the continuous application of loads generated by the traffic creates a progressive damage in the pavement layers. Currently, there are different methodologies that allow predicting the fatigue cracking, but most of these methodologies are complex procedures which may not guarantee the failure of some types of mixtures and may not relate the applied load conditions to those suffered in the pavement. For this reason, to understand the fatigue craking behavior of asphalt mixtures is essential to develop effective fatigue tests. In this context, the main goal of this paper is to propose a test methodology to evaluate fatigue cracking by using a notched cylindrical asphalt concrete specimen. The proposed method allows reproducing the pavement tensional state, avoiding the stress dissipation, and focusing the strains in the middle of the previously groove carved specimen. A semi dense asphalt mixture gradation, used in asphalt pavement surface layer, were chosen. Three types of aggregates were evaluated, determining their fatigue laws. Besides, an analysis of durability of asphalt mixtures was presented.