Abstract
<title>Abstract</title> <p> Thermal cracking, rutting, and moisture damage are common pavement distresses caused by heavy traffic growth, construction deficiencies, and environmental effects, reducing service life and performance. Asphalt additives can improve pavement behavior; however, a single modifier rarely enhances all properties simultaneously. This study investigates a composite modification approach using dual additives in reclaimed asphalt pavement (RAP). Five mixtures were evaluated: control mix, RAP mix, RAP with waste cooking oil (WCO), RAP with nano Fe2O3, and RAP with a composite of WCO and nano Fe2O3. Marshall immersion, low-temperature splitting, and wheel tracking tests were conducted to assess moisture resistance, thermal cracking, and rutting performance. Environmental performance was evaluated using life cycle assessment (LCA) with SimaPro software. Results indicate that nano Fe <sub>2</sub> O <sub>3</sub> improved rutting resistance and moisture stability, while WCO enhanced low-temperature cracking resistance. The composite-modified mixture achieved the best overall mechanical performance. Environmentally, RAP modified with nano Fe <sub>2</sub> O <sub>3</sub> showed the lowest impacts. </p>