Effects of Various Asphalt Binder Additives/Modifiers on Moisture-Susceptible Asphaltic Mixtures.

摘要

Moisture damage of asphalt concrete is defined as the loss of strength and stability caused by the active presence of moisture. The most common technique to mitigate moisture damage is the use of additives or modifiers with the asphalt binder or the aggregate. The objective of this study was to investigate the effect of various additives and modifiers on moisture susceptibility of asphalt concrete. The additives and modifiers selected for study were liquid anti-strip (LAS), styrene butadiene styrene (SBS), polyphosphoric acid (PPA), and hydrated lime. Two moisture-susceptible mixes were selected for testing. Tests at both mixture and component levels were conducted to evaluate the impact of these additives and modifiers on mixture moisture damage. The mixture-level lab tests included the modified AASHTO T283 Lottman test with five freezing and thawing (FT) cycles, the wheel tracking test, and a fracture test using semi-circular bending (SCB) specimens. The component-level tests included the direct adhesion test (DAT) and surface free energy (SFE) test. The modified AASHTO T283 Lottman tests showed that LAS and hydrated lime improved moisture resistance of the asphalt mixes. In the wheel tracking tests, mixes with SBS-modified asphalt binder and mixes with hydrated lime provided the least rutting potential. The fracture tests generally showed that mixes with either hydrated lime or LAS had the best relative performance. Results of SFE tests and DATs were in agreement with the results of mixture-level tests: LAS and hydrated lime can mitigate a mixtures susceptibility to moisture. Full-scale test sections were built and exposed to accelerated load testing.