Effects of liquid antistrip additives on rheology and moisture susceptibility of water bearing warm mixtures

Warm mix asphalt (WMA) has been gaining increasing popularity in recent years around the world. Rising energy prices, global warming, and more stringent environmental regulations have resulted in an interest in WMA technologies as a mean to decrease the energy consumption and emissions. However, the water absorption and release process caused by water bearing WMA additive (Asphamin) makes the charge re-distribution complex and thus may result in the moisture induced damage of asphalt mixtures. Especially, the liquid antistrip additives (ASAs) blended with the binder and then mixed with aggregate and Asphamin make the issue more complicated. The objective of this study was to investigate and evaluate the rheological properties and moisture susceptibility of the binder and mixture containing ASAs and Asphamin additive. The experimental design for this study included rheological property tests of binders and moisture susceptibility of mixtures. The materials included one binder (PG 64-16), two liquid ASAs and hydrated lime, one water bearing additive, and three aggregate sources. The performed testing included viscosity, performance grade, creep and creep recovery, amplitude sweep, frequency sweep, boiling test, and indirect tensile strength (ITS). The results indicated that the addition of Asphamin can slightly increase the viscosity, failure temperature and G*/sin δ values. The mixture containing Asphamin has a lower ITS value than others. Statistical analysis illustrates that there is not significant difference in ITS value between any mixtures containing Asphamin additive and control mixtures. However, significant differences can be found between mixtures containing Asphamin and without any Asphamin additive.