The use of hydrated lime or other liquid anti stripping agents (ASA) is the most common method to improve the moisture susceptibility of asphalt mixes. However, most laboratory test conditions used to evaluate the moisture susceptibility of the mixes are only for a short duration of time. This might not be a good representation of the field conditions (i.e., several months or years of service). Thus, a study to evaluate the effects of conditioning the mixes for longer durations was initiated. Also, another problem with the use of the liquid anti stripping agents is their heat storage stability. This report addresses these two issues, by preparing and testing mixtures made with fresh binder for indirect tensile strength after conditioning the samples for 1, 7, 28, 90 and 180 days, and samples prepared from binder stored for three days at 160° C after conditioning them for 1, 28 and 90 days. The results of this study indicated that hydrated lime and the liquid anti stripping agents were equally effective for the mixes used in this research when conditioned beyond one day. In the case of samples prepared from stored binder, there was no significant difference in the effectiveness of hydrated lime and the liquid anti stripping agents even after conditioning for one day. Though it was observed that none of the ASA treatments performed better than others in the case of samples prepared with stored binder, it was also observed that almost all mixes gave significantly similar wet ITS and TSR values as samples prepared from fresh binder.

The use of hydrated lime or other liquid anti stripping agents (ASA) is the most common method to improve the moisture susceptibility of asphalt mixes. However, most laboratory test conditions used to evaluate the moisture susceptibility of the mixes are only for a short duration of time. This might not be a good representation of the field conditions (i.e., several months or years of service). Thus, a study to evaluate the effects of conditioning the mixes for longer durations was initiated. Also, another problem with the use of the liquid anti stripping agents is their heat storage stability. This report addresses these two issues, by preparing and testing mixtures made with fresh binder for indirect tensile strength after conditioning the samples for 1, 7, 28, 90 and 180 days, and samples prepared from binder stored for three days at 160° C after conditioning them for 1, 28 and 90 days. The results of this study indicated that hydrated lime and the liquid anti stripping agents were equally effective for the mixes used in this research when conditioned beyond one day. In the case of samples prepared from stored binder, there was no significant difference in the effectiveness of hydrated lime and the liquid anti stripping agents even after conditioning for one day. Though it was observed that none of the ASA treatments performed better than others in the case of samples prepared with stored binder, it was also observed that almost all mixes gave significantly similar wet ITS and TSR values as samples prepared from fresh binder.

This project evaluated the influence of anti-strip additives on the durability and moisture susceptibility of granite-based open-graded friction course, referred to as FC-5 asphalt mixtures. The laboratory testing involved two granite-based FC-5 mixtures containing 1% hydrated lime (by weight of aggregate), 1% hydrated lime plus 0.5% liquid anti-strip (LAS) additive (by weight of asphalt binder), 1.5% hydrated lime, and 1.5% hydrated lime plus 0.5% LAS additive. Two sources of granite aggregates were obtained: one from Junction City, Georgia and the other from a regional supplier with an original source from Nova Scotia, Canada. Four types of LAS additives were collected from Road Science ArrMaz, Inc. and Ingevity, Inc. The binder bond strength test was used to select the LAS agents that provided the best improvement in moisture resistance. The FC-5 mixtures were fabricated in the laboratory using two FC-5 mix designs provided by the Florida Department of Transportation. The specimens were conditioned by the asphalt pavement weathering system to simulate the long-term aging and moisture conditioning in the field. Mixture performance tests, including the Cantabro test, tensile strength ratio test, and Hamburg wheel tracking test, were used to comprehensively evaluate the durability and moisture susceptibility of FC-5 mixtures. Finally, a cost-benefit analysis was performed to determine the cost-effectiveness of the FC-5 mixtures with anti-strip additives. This project found that the addition of LAS additive, extra 0.5% hydrated lime, or both produced longer lasting FC-5 mixtures, and the additional anti-strip additives would improve the cost effectiveness of FC-5 mixtures.

Moisture susceptibility of hot mix asphalt (HMA) pavements continues to be a major pavement distress. Past research has primarily focused on HMA stripping prevention through material component evaluation/testing and addition of preventative additives. Stripping is caused by traffic, water, and high in-place service temperatures. Today, agencies use various methods to evaluate HMA moisture susceptibility with varying degrees of success. The study objective was to evaluate a prototype stripping simulator's ability to predict HMA moisture susceptibility. The simulator evaluates moisture susceptibility by measuring conditioning water turbidity. Boil test and indirect tensile strength testing were also conducted for comparison purposes. Stripping simulator results indicate further refinement is required before it can be used for moisture susceptibility prediction.