Performance evaluation of asphalt mixtures containing warm mix asphalt (WMA) additives and reclaimed asphalt pavement (RAP)

Abstract

Global warming and reduced available energy resources have provided strong incentives to find alternative materials and technologies for the construction of pavements. Technologies such as asphalt recycling or warm mix asphalt (WMA) can provide several economic and environmental benefits. This research was initiated to investigate the mechanical and durability performance of WMA mixtures containing 0% and 50% reclaimed asphalt pavement (RAP) made with different types of WMA additives including Sasobit®, Kaowax®, Zeolite®, and PAWMA®. For this purpose, various mechanical tests including dynamic creep at 54.4 °C, resilient modulus at three temperatures of 5 °C, 25 °C, and 40 °C, indirect tensile strength (ITS) at 25 °C, and semi-circular bending (SCB) fracture at about 25 °C were conducted. The durability performance of the mixtures was evaluated by calculating the tensile strength ratio (TSR) to investigate the moisture susceptibility of the mixtures. The findings indicated that the mechanical performance of the mixtures depends on the type of WMA additive. Among all the WMA additives evaluated in this study, only PAWMA® decreased the resistance of asphalt mixture to moisture damage. Although the incorporation of RAP material into asphalt mixtures decreases the flexibility and cracking resistance of the mixtures, it leads to a significant improvement in resisting the damages associated with rutting. The mixture containing RAP and Kaowax® resulted in the highest flow number value, while the HMA mixture containing Zeolite® resulted in the lowest flow number value. Moreover, the incorporation of RAP material into asphalt mixtures was found to enhance the moisture damage resistance, the asphalt mixtures containing RAP and PAWMA® showed the highest resistance to moisture damage among all the mixtures studied in this research. In addition, the asphalt mixtures containing RAP and made with Sasobit®or PAWMA® showed the highest resilient modulus and cracking resistance among all the mixtures, respectively.