Mechanical performance of fiber-reinforced concrete incorporating rice husk ash and recycled aggregates

This study explores the incorporation of rice husk ash (RHA) and recycled concrete aggregate (RCA) in concrete to address environmental concerns by reducing waste and conserving natural resources. A detailed experimental analysis was conducted to assess the mechanical properties of concrete when ordinary Portland cement (OPC-43) was partially replaced with RHA (up to 20%) and natural aggregate (NA) was replaced with recycled concrete aggregate (up to 30%). The experimental results revealed that partial replacement of OPC-43 with 20% RHA led to an increase in compressive strength (CS), flexural strength (FS), and split tensile strength (STS) by 7.37%, 8.87%, and 10.28%, respectively. In contrast, increasing RCA content in the mix continuously decreased strength. However, with up to 30% RCA, the rate of strength reduction was limited to less than 4%. Beyond this point, strength reduction rates exceeded 18%, identifying 30% RCA as the optimal replacement level for balancing sustainability and mechanical performance. Among the tested fibers, hooked steel fibers yielded the most significant improvements, increasing CS by 8.27%, FS by 24.35%, and STS by 22.38%. These findings highlight the potential of using RHA and RCA in concrete, supported by the strategic use of fibers, to enhance both sustainability and mechanical properties.