An Experimental Study of the Use of EPS in Bituminous Mixes Prepared with RAP

This study explores the combined use of Reclaimed Asphalt Pavement (RAP) and Expanded Polystyrene (EPS) as sustainable and performance-enhancing materials in Bituminous Concrete Grade-2. With the growing focus on environmentally friendly road construction, the use of RAP helps reduce the consumption of virgin aggregates and bitumen, while also minimizing waste generation and energy use. EPS, a lightweight and recyclable plastic waste, is known to improve the stiffness and thermal resistance of bitumen when used as a modifier. The experimental program began with the sample being prepared for a control mix with varying binder content. The optimum binder content for the control mix was determined to be 5.65% using the Marshall Method. Subsequently, modified bituminous mixes were prepared by incorporating RAP at 27.5%, 30%, and 32.5%, and EPS at varying contents from 3% to 7%. Laboratory testing was conducted in accordance with ASTM standards. It included Marshall Stability, Flow Value, Bulk Density, Air Voids, VMA, VFB, and ITS. The results indicated that the inclusion of RAP increased the stability of the mix and reduced the requirement for fresh binder due to the presence of aged bitumen. The addition of EPS resulted in an increase in the softening point and a decrease in the penetration value, indicating improved stiffness and resistance to high temperatures. Overall, the optimum use of 27.5% RAP and 5% EPS produced bituminous mixes with higher stability, desirable air void content, improved crack resistance, and enhanced tensile strength compared to conventional mixes. The study concludes that RAP and EPS can be effectively utilized in bituminous concrete to lower environmental impact and reduce material costs. These findings support the use of recycled materials in highway construction and highlight the need for further research on the long-term field performance and optimization of RAP–EPS proportions for practical applications.