Evaluating the Suitability of Reclaimed Asphalt Pavement and Crumb Rubber in Asphalt Mixes Using Marshall Analysis

Growing environmental problems and natural resource exhaustion have led to increased interest in sustainable pavement materials. Recycling is an important process because it aids the conservation of natural resources and decreases waste and the environmental impact of the disposal of waste. In this study, an evaluation of the Marshall characteristics of bituminous mixes incorporating reclaimed asphalt pavement (RAP) and crumb rubber (CR) was carried out to conserve resources and better performance. Eight different mixes (A-H), with varying RAP content (0–100%), CR content (0–25%), and fresh aggregates, were prepared. The results demonstrated that mixes containing recycled materials performed comparably to conventional mixes. Mix F (90% fresh aggregate, 10% RAP, and 20% CR) showed a stability of 14.43 kN, close to the conventional mix (14.6 kN). The optimal bitumen content showed a steady increase from 5.31% (Mix A) to 5.65% (Mix H), while the values of air voids (Va) and voids in mineral aggregate (VMA) increased slightly, but remained within permissible limits. The study concluded that up to 30% of virgin materials can be replaced by coarse aggregate from RAP (10%) and fine aggregate from CR (20%) without compromising mechanical integrity, thereby providing a cheaper and more sustainable option. These results provide a strong basis for encouraging the industry to adopt recycled materials because of global sustainability while addressing some of the construction problems in Bangladesh.