Material Modification and Performance Evaluation of Cold Mix Asphalt (CMA) Produced with Dissolved Waste Polythene as Partial Replacement of Bitumen

Abstract

Road surfacing repairs are conventionally undertaken using hot mix asphalt, a process associated with significant challenges, including fire hazards and contributions to global warming due to the elevated temperatures required to ensure adequate fluidity of the viscous binder during the production of bituminous materials. As an alternative, cold mix asphalt presents a more environmentally sustainable option, particularly when produced using non-biodegradable polythene packaging waste, which is commonly discarded in open environments across both rural and urban areas in developing countries. The incorporation of such waste materials offers multiple advantages, including the reduction of environmental pollution caused by dispersed polyethylene debris, decreased reliance on bitumen, and mitigation of bitumen oxidation. In this study, the cold mix asphalt binder was prepared by modifying bitumen with 5% dissolved polythene by weight, across varying binder contents. The asphalt mixture was formulated in accordance with a specified design mix comprising 25% coarse aggregates, 5% fine aggregates, and 70% quarry dust. The results demonstrated that plastic modification at an optimum binder content of 6% produced the highest Marshall stability, with all volumetric parameters remaining within acceptable specification limits. Additionally, the modified mixture exhibited notable resistance to moisture-induced damage, with stability values of 7.4 kN and 7.24 kN recorded for mixtures with and without dissolved polythene, respectively, both exceeding the minimum requirement of 3 kN. Overall, the findings indicate that the incorporation of dissolved polythene into asphalt mixtures is both technically feasible and beneficial, enhancing mechanical performance and durability. This approach represents a promising and sustainable strategy for large-scale plastic waste utilisation in infrastructure development.