Developing a Novel Testing Configuration for Assessment of Fatigue Resistance in Asphalt Concrete Mixtures

Abstract

Laboratory testing of asphalt concrete (AC) mixtures is a critical element of transportation engineering that facilitates performance-based design. Over time, numerous tests have been developed to evaluate AC mixture performance to withstand different distress types. This study offers an initial evaluation of a novel test configuration to evaluate the mixture cracking performance with the following key features: ease of preparation, potential use of field cores, possible implementation in quality control, potential use of both monotonic and cyclic loading, simulation of layer bending and an elastic sublayer support. The proposed testing configuration utilizes common 150-mm diameter samples lying flat on a cylindrical support with or without a supporting aluminum plate with loading applied to the uncut compacted surface or a cut face. In this configuration, the AC sample is subject to bending with maximum strains at the bottom of the sample beneath the load mirroring the state of stresses which are related to bottom-up fatigue cracking seen in AC pavement structures.The results of this study yielded a finite element model of the state of stresses present in the proposed testing configuration along with laboratory validation and troubleshooting of the test configuration geometry and procedure. Based on the experimental validations and several trials performed with various configurations, an optimized setup of a 30-mm thick sample supported with a 3-mm beveled aluminum pipe and a rubber load applicator was developed in combination with a quick and relatively simple procedure to be used in a monotonic loading mode for correlation to fatigue cracking performance.