Test methods to evaluate the effect of interface bond conditions on top-down and reflective cracking

Abstract

A composite specimen interface-cracking (CSIC) test was developed to evaluate the effect of the characteristics of the interface between asphalt layers on resistance to top-down and reflective cracking. The system involves repeated tensile loading and monitoring of the rate of damage development (reduction in stiffness) on composite specimens specifically designed for this purpose. Top-down cracking tests were performed on open-graded friction course (OGFC) mixtures placed on dense-graded mixtures using both a conventional tack coat and a polymer-modified asphalt emulsion (PMAE) at a higher application rate. Reflective cracking tests were performed on dense-graded mixtures. Results clearly indicated that use of polymer-modified bonding material significantly reduced the rate of damage development for both top-down and reflective cracking. The testing and interpretation methods developed can be used to optimize bonding materials and application rates for enhanced cracking performance. The methods may also provide a suitable specification test for bonded systems.