Volume 34, Issue 4 (July 2006)
A Laboratory Study of the Effectiveness of Various Additives on Moisture Susceptibility of Asphalt Mixtures
Antistripping additives are used routinely to improve water resistance of asphalt mixtures. Different additives have different improvement effectiveness in water resistance. In this study, the effects of various additives on the moisture susceptibility of asphalt mixture are studied with the retained Marshall stability test, Lottman test, and immersion wheel tracking test. Asphalt mixtures were modified with Portland cement, hydrated lime, lime slurry, and liquid antistripping agents. The results show that the lime-slurry-treated asphalt mixtures have better resistance to moisture susceptibility than mixtures treated with other materials, and have better long-term moisture stability than the liquid antistripping agents. The liquid-antistripping-agent-treated asphalt mixtures have better resistance to moisture stability before long-term aging. Portland-cement-treated asphalt mixtures show slightly improved water resistance. Asphalt mixtures become more resistant to moisture damage through short-term aging. It was confirmed that the Lottman and the immersion tracking methods are better methods to evaluate moisture susceptibility than the retained Marshall stability methods.