Effects of Aging on Moisture Damage of Hot Mix Asphalt containing Wetfix Additive and Granite and Limestone Aggregates

Aging is one of the factors affecting the physical and chemical properties of bitumen. This factor can lead to moisture damage in the asphalt mixture. The objective of this study is to investigate the effect of short- and long-term aging on the moisture damage mechanisms of hot mix asphalt containing Wetfix using the Pull-off method. Two types of bitumen with different performance grades (PG 58-22 and PG 64-16) modified with Wetfix BE additive and two types of aggregate (limestone and granite) were used. First, the rheological properties of bitumens and the physical characteristics of aggregates were determined, and then the chemical compositions of aggregates were obtained through an X-ray fluorescence (XRF) test. After modifying the bitumens with Wetfix, the pull-off test was performed to determine the cohesion strength of bitumen and the adhesion strength of bitumen to aggregate on aged and unaged samples in dry and wet conditions. Short-term aging increased the cohesion strength and long-term aging caused a decrease in cohesion strength in wet conditions. Therefore, long-term aging leads to a decrease in bitumen performance in wet conditions and as a result, a decrease in pavement resistance against moisture damage. However, adding Wetfix increased the cohesion strength between 20-32% and 26-48% in short and long-term aging, respectively, and adhesion strength between 43-26% and 57-38% in short- and long-term aging, respectively. Comparing the effects of aging of base and modified bitumen on the reduction of adhesion and cohesion strengths shows that the addition of Wetfix not only eliminates the negative effects of aging on these parameters, but also improves the resistance of modified bitumen compared to base bitumen against moisture damage.