Development of compression pull-off test (CPOT) to assess bond strength of bitumen

Abstract

Abstract The quantification of moisture susceptibility has been a major concern for researchers as it adversely affects the performance of asphalt pavements. Several methods have been developed to assess bond strength using asphalt mixtures in loose and compacted state. These tests lack in their ability to study fundamental properties that affect the bond between bitumen and aggregate. In this context, more fundamental techniques have been developed such as pull-off stub tests and direct tension tests. The first group only measures the maximum pull-off strength and second group has problems related to use of consistent binder film thickness and operational difficulties in test itself. This paper presents a new test to evaluate bond strength, in an attempt, to solve problems associated with traditional direct tension tests. The aim is achieved through a review of existing techniques, development of a gap assembly, fabrication of direct tension test moulds, development of Compression Pull-Off Test (CPOT) and evaluation of its results. The key parameters for bitumen and mastics were evaluated. The CPOT shows promising results for use of this technique to study cohesive as well as adhesive bond strength of binder.