Rubber and plastic waste-modified asphalt binders and mixtures: Performance against environmentally induced distresses-A review

To assess the long-term durability of waste-modified binder and asphalt mixtures as sustainable pavement solutions, their performance against the most dominant environmentally induced distresses in the extreme weather environments is studied. This is critical for utilization of such solutions since many roads can be subject to flood, high UV and extreme temperatures. This review focuses on Crumb Rubber Modified Binder (CRMB) and Recycled Plastic-Modified Binder (RPMB) to enhance their performance predictability and support their broader use in pavements. While the immediate benefits are well-documented, a focused review on the mechanisms of environmental degradation and their impact on performance is lacking. CRMB exhibits unique ageing mechanisms, displaying resistance to oxidative, thermal, and UV ageing, offering promise for enhancing asphalt durability in harsh environments. In contrast, when exposed to UV, RPMB tends to present a complex interplay of factors influenced by polymer type, dosage, and environmental conditions that variability would affect the reliability of the product and thus suggests the need for further research. Moisture-induced distress in CRMB and RPMB asphalt mixtures is also considered, highlighting the challenges and opportunities for improving moisture susceptibility of these binders. In the literature, chemical interaction between crumb rubber and binder enhances aggregate adhesion, while undissolved crumb rubber particles may hinder it; however, consensus is lacking on their collective impact alongside other mixture parameters on the moisture resistance of asphalt. Asphalt mixtures with recycled plastics have shown acceptable moisture resistance; however, further research is needed to understand the interplay between recycled plastic properties (polarity, melting point, chemical structure) and mixture characteristics (plastic content, mixing method, temperature) to enhance reliability.