Elaborating the 3D microstructural characteristics and strength softening mechanical mechanism of fiber-reinforced recycled aggregate concrete

Abstract

Recycled aggregate concrete (RAC) is a sustainable and low-carbon construction material, but it tends to have inferior physico-mechanical properties compared to natural aggregate concrete. This study aims to enhance these properties to make RAC a viable alternative for broader construction applications. By incorporating steel fibers (SF) and polypropylene fibers (PPF) into RAC, the mechanical properties, particularly crack resistance and post-peak strength softening, were significantly improved. Extensive low-cycle loading tests were conducted to assess the strength softening behavior and energy dissipation capacity. The results showed that fibers increased post-peak strength softening resistance by up to 30 % for SF and 25 % for PPF. Proposed strength softening models based on residual strain accurately predict the effects of fiber dosage on the composite’s properties, providing a technical foundation for RAC engineering applications.