EVALUATION ON PERFORMANCE OF MODIFIED ASPHALT MIXTURES WITH RECLAIMED ASPHALT PAVEMENT MATERIALS

Abstract

The increasing demand for pavement construction materials has created environmental and economic challenges due to depletion of natural aggregates, rising costs, and stricter regulations. Reclaimed Asphalt Pavement (RAP) offers a sustainable solution by recycling existing materials, reducing landfill waste, and minimizing the use of virgin aggregates and binders. This study investigates the performance of asphalt mixtures incorporating RAP along with nanomaterials NanoSilica (NS) and NanoClay (NC) to enhance strength, durability, and microstructural properties. Experimental work was conducted with RAP contents of 15%, 30%, and 45%, and nanomaterial additions ranging from 2% to 6%. Marshall stability tests revealed that 30% RAP improved stability significantly, while 6% NS modification further enhanced stability to 21.28 kN compared to 18.43 kN with 4% NC. Indirect Tensile Strength (ITS) and Tensile Strength Ratio (TSR) tests confirmed improved moisture resistance, with NS-modified mixes achieving TSR values above 94%, surpassing the minimum threshold of 80%. Rutting resistance was also enhanced, with NS-modified RAP mixes showing superior performance under repeated loading cycles. Microstructural analyses (XRD, SEM, EDAX) validated the formation of dense, well-bonded structures with high silica and calcium content. Statistical modeling using Response Surface Methodology (RSM) achieved strong predictive accuracy (R² > 0.92), identifying RAP content as the most influential factor. The findings demonstrate that optimal combinations of 30% RAP with 6% NS or 4% NC provide superior mechanical and durability properties, supporting sustainable pavement construction practices.