Study on the mechanical properties and deterioration mechanism of recycled aggregate concrete for low-grade highway pavements

This study is motivated by the imperative for sustainable construction practices, specifically focusing on recycling construction waste into low-grade highway pavements to enhance environmental sustainability and resource efficiency. The investigation explores the workability, mechanical properties, and interfacial transition zones (ITZs) of recycled aggregate concrete (RAC), emphasizing the incorporation of recycled coarse aggregate (RCA) from construction waste. The primary objective is to delineate the optimal mixture proportions of RAC that effectively balance resource utilization with the technical requisites for low-grade highway pavements. Through rigorous orthogonal testing and analysis, a mixture was identified that achieves a high RCA replacement rate while preserving workability and mechanical properties. Additionally, nanoindentation tests were employed to probe the nanomechanical properties of the ITZs in RAC, aiming to elucidate the underlying degradation mechanisms. Results reveal that the porous and rough surface of RCA significantly impacts the properties of RAC, with a marked decrease in elastic modulus and an increase in ITZ width identified as primary contributors to mechanical deterioration. Consequently, this study not only provides crucial insights for the application of RAC in low-grade highway pavements but also sets the stage for future research aimed at enhancing the sustainability and performance of recycled construction materials.