Book Description

Moisture damage of asphalt mixes, better known as stripping, is a major distress affecting pavement performance. AASHTO T 283 (KT-56) has been used by many agencies over the past decade to detect moisture susceptible pavements through the determination of a tensile strength ratio (TSR). Results from AASHTO T 283 (KT-56) have been inconsistent. As a result, there has been increased interest in finding an alternative test method. Preliminary indications reveal that loaded wheel rut testers, such as the Asphalt Pavement Analyzer (APA), have the potential to detect moisture susceptible mixtures. To date no standard test methodology has been developed. The objective of this project was to evaluate the effects of sample preconditioning on APA rut depths and to further evaluate the APA's suitability for predicting moisture susceptible mixtures. Eight different mixes from seven project sites were evaluated with the APA. Samples were tested at 40 deg C using four different preconditioning procedures: dry, soaked, saturated, and saturated with a freeze cycle. The results were compared with TSR values, methylene blue values and sand equivalent. The APA was able to identify every mix with a failing TSR.