Developing a Tensile-Shear Testing Setup for Asphalt Layers

Abstract

Interface bonding condition between asphalt courses plays a critical role in the pavement performance. One of the most common distresses is slippage failure, which usually occurs where heavy vehicles are often accelerating, decelerating, or turning. Other pavement problems that have been linked to poor bonding between pavement layers include premature fatigue, top down cracking, pothole, and surface layer delamination, which reduces the serviceability and performance of a pavement. There are many factors affecting the interface bonding condition, including 1) improperly cleaned interface; 2) cold temperature during placement; 3) insufficient curing, and 4) improper selection and application rate of material. Since an asphalt pavement has multi-layered structure system, the interfaces between layers are essential to the pavement performance. An interface between a surface course and an intermediate course is more emphasized since critical temperature and stress conditions for asphalt top-down cracking, rutting, and shearing are present near the pavement surface. 4 Many test methods have been developed to evaluate the interface condition in the lab and the field.There is, however, no standard test method for the evaluation. In addition, available test methods has limitation including: 1) indirect measurement, 2) limited application to the field, 3) limited measurement range, 4) acquisition of undisturbed-interface sample from coring process, and 5) lack of practicality for QC/QA. Correlation of the interface bonding to pavement performances is essential in a performance based specification for a tack coat practice. A tack coat is inexpensive, but it’s influence on pavement performance is significant.