Establishing Design Limits for Cracking Properties of Asphalt Concrete with Overlay Tester

The premature cracking of the asphalt concrete (AC) layer in flexible pavements highlights the importance of a simple cracking performance test that can be used for routine applications during the design process of AC mixes. The overlay tester (OT) can be used to evaluate the formation and propagation of a crack within the AC specimens. This paper explains an alternative methodology for assessing the cracking potential of AC mixes using the OT test. The proposed methodology consists of two main stages: crack initiation and propagation. The fracture properties of the AC specimens are estimated from the critical fracture energy computed from the first OT loading cycle. The resistance of the AC mix to crack propagation is estimated from the crack progression rate, the rate of reduction in load carrying capacity of the AC specimen with the number of cycles. The process of selecting the limits for the critical fracture energy and crack progression rate to delineate the well and poor performing mixes is discussed here. The proposed cracking methodology and acceptance limits may provide a more comprehensive approach to predict and design the cracking potential of AC mixes.