Comprehensive Study on Mechanical and Transport Properties of Roller-Compacted Concrete Incorporating Reclaimed Asphalt Pavement

This study assesses the feasibility and effects of incorporating reclaimed asphalt pavement (RAP) into roller-compacted concrete (RCC) for pavement applications. Six RCC mixtures, incorporating varying RAP fractions (0% to 100% as volumetric substitutions of natural aggregates), were formulated and evaluated for their fresh, mechanical, and transport properties. Scanning electron microscopy (SEM) analysis was conducted on the RCC mixture containing 100% RAP. The results indicated a decrease in overall mechanical properties as RAP content increased, with 28-day compressive and split tensile strengths declining by 70% and 40%, respectively, in the case of full replacement. This decline in mechanical performance was accompanied by heightened porosity and sorptivity. Nevertheless, RCC mixtures with up to 60% RAP met pavement construction specifications. SEM micrographs revealed significant pore concentration, especially in the interfacial transition zone between RAP aggregates and the cementitious matrix, indicating poor adhesion between these RCC phases. Furthermore, empirical correlations were established to illustrate the influence of RAP content and increased porosity on RCC's mechanical properties and sorptivity. These correlations allow engineers to predict the characteristics of RCC for any RAP rate and provide insights into the impact of substituting natural aggregates with RAP on porosity and, consequently, RCC's hardened-state characteristics.