Experimental Study of HMA Absorption According to Aggregate Types and Asphalt Grade

Different aggregate types tend to absorb asphalt differently, and these absorption and permeability properties can reduce costs and environmental pollution. At present, virgin aggregates (VA) with high-quality properties are not often used. Even though the quality of recycled asphalt pavement (RAP) and recycled concrete aggregates (RCA) is low in some cases, most studies tend to use them. There are many tests used to calculate asphalt absorption. Most studies have been concerned with only the total absorption causes and have not addressed their selective natures. Therefore, studying the asphalt absorption phenomenon regarding the aggregates and asphalt properties is important. Three types of aggregates with different absorption properties were used to achieve this research goal: VA, RAP, and RCA. In addition, three asphalt grades 40–50, 60–70, and 85–100 were used to determine the relationship between asphalt and water absorption. The results showed that aggregates with a high degree of water absorption could absorb at a higher rate, and this relationship affects aggregate behavior and the layers' future performance. The asphalt absorption rate increased with an increase in the viscosity of the asphalt at the mixing temperature, noting some increases were due to selective absorption. Furthermore, this study observed that the absorption ratio of both natural aggregates and recycled aggregates is related to the aggregate surface area. Based on these results, recycled aggregates are recommended to reduce the depletion of natural aggregates. The absorption ratio time also reduces waste, thus reducing economic and environmental costs.