Feasibility of utilizing recycled concrete aggregate blended with waste tire rubber and drywall waste as pavement subbase material

As a developing nation, Pakistan faces financial obstacles in road construction, which is essential for economic growth but costly. A sustainable approach to address environmental concerns involves using recycled materials in road construction. The construction industry has largely overlooked recycling despite the significant amount of debris generated during construction and demolition. Repurposing materials from building and demolition activities, such as rubber from tires and drywall waste, can serve as viable materials for subbase layers in roads. These recycled materials can improve road quality and performance while mitigating environmental and health risks associated with stockpiling and disposal. This research evaluates the physical and mechanical properties of recycled concrete aggregates (RCA) combined with drywall waste (DW), waste tire rubber (WTR), and quarry dust (QD) for flexible pavement subbases. The study investigated the effect of adding 0.5%, 1%, 1.5%, and 2% crumb rubber with 5%, 10%, 15%, and 20% DW as a percentage of fine aggregate with QD in RCA. By subjecting RCA to a series of tests, their strength, durability, and stability are thoroughly assessed to determine the optimal ratios of WCR and DW. As a result of these evaluations, a notable improvement in compressive strength is observed. Cost analysis demonstrates the economic feasibility of using recycled materials in pavement subbase construction, offering a cost-effective, sustainable, and environmentally safe solution that reduces reliance on fresh aggregates (FA).