Experimental evaluation of reclaimed asphalt pavement (RAP) and anti-stripping additive on the performance of half-warm mix asphalt (HWMA)

With the growing emphasis on sustainable development, reducing the use of virgin materials, energy consumption, greenhouse gas emissions, and environmental pollution, are among the priorities in the pavement industry. Hot Mix Asphalt, produced at temperatures above 150 °C, involves high fossil fuel consumption and significant pollutant emissions, causing serious environmental problems. This study employs the production technology of Half-Warm Mix Asphalt (HWMA) which is produced at temperatures below 100 °C, thereby reducing energy use and pollution. Additionally, to promote recycling and reduce the use of new raw materials, RAP was used at 0%, 50%, 70%, and 100% in the HWMA mixtures. Considering the importance of moisture susceptibility in evaluating asphalt mixture performance, pull-off tests on emulsion bitumen were conducted to assess bitumen adhesion. Furthermore, Marshall stability, indirect tensile strength, and resilient modulus tests were conducted on mixtures with and without the anti-stripping agent GRIPPER. Results showed that increasing the RAP content improved moisture resistance, as evidenced by an increase in the TSR from 61.7% for the control mixture to 77.8% for the 100% RAP mixture. Additionally, incorporating the anti-stripping agent further enhanced the TSR by 15.9–20.5%, leading to a peak TSR value of 93.6%, which significantly reduced moisture susceptibility, especially in mixtures with fully siliceous aggregates. These findings highlight the feasibility of using such mixtures in various pavement applications under realistic laboratory testing conditions. The study indicates that combining HWMA technology with recycled materials improves pavement durability and strength, highlighting its performance potential for sustainable construction practices.