Moisture Susceptibility of WMA Containing Zycotherm and RAP

In recent years, the use of warm asphalt technology and reclaimed asphalt pavement (RAP) has been extensively used to reduce the costs of pavement construction, as well as to protect the environment. Nonetheless, concern about moisture susceptibility is an important issue related to warm asphalt mixtures. In this study, we examined the effect of different percentages of RAP on the moisture susceptibility of warm asphalt mixtures containing Zycotherm as a nano-chemical additive. Two types of aggregates including siliceous and calcareous minerals (which have been shown to be have different performance characteristics against moisture damages) were used in the production of warm asphalt mixtures. A total of 48 samples of asphalt mixture containing different percentages (15, 30 and 45 percent) of RAP were evaluated. Indirect tensile strength test (ITS) and Texas boiling test were carried out to investigate the moisture susceptibility of samples. Results demonstrated that addition of RAP to both types of aggregates increased the moisture susceptibility of the mixture. Experiments showed that adding 45 percent of RAP resulted in 19 and 23 percent reduction in TSR for the mixtures containing siliceous and calcareous aggregates, respectively, which was corresponding to 30 and 25 percent stripping of aggregate-asphalt mixtures in siliceous and calcareous aggregates, respectively.