Impact of Antistrip Additives on the Long-Term Aging Rheological Properties of Asphalt Binders

Abstract

Hydrated lime and liquid antistrip agents have long been used as an asphalt additive to improve resistance to moisture damage. Previous studies have shown that the addition of hydrated lime to asphalt binders reduced the aging propensity of asphalt by adsorbing naturally occurring oxidation catalysts or promoters from the asphalt binders. This study was conducted to evaluate the impact of lime and liquid antistrip on the long-term aging of five asphalt binders. The first part of the study evaluated the intermediate- and low-temperature rheological properties of these asphalt binders with no additive, blended with hydrated lime, and blended with liquid antistrip. The rheological properties of the binders were evaluated at the original and long-term aged stages. The second part of this effort evaluated the aging characteristics (e.g., G*sinδΔ, creep stiffness, and m-value) of the binders with and without the antistrip additives. The work in this study was designed to determine how the rheological properties of antistrip-treated asphalts vary with aging time when compared with untreated asphalts aged at temperatures in the pavement temperature range. An apparent question begging an answer is whether antistrip-treated asphalt ages to the same viscosity as an untreated asphalt when other rheological properties are similar. The test results indicated that hydrated lime stiffens the binders but it does not negatively impact their long-term aging characteristics. Therefore, lime-treated binders are expected to be stiffer than untreated and liquid-treated binders in their early life which increases their resistance to rutting but not too brittle in their later life to negatively impact their resistance to fatigue and thermal cracking.