Statistical study of mechanical properties of steel fibre recycled aggregate concrete

Recycled aggregate concrete (RAC) offers environmental benefits but its structural application is limited due to inferior mechanical performance compared with conventional concrete. The incorporation of steel fibres has shown potential to overcome these limitations. This study investigates the interaction between recycled concrete aggregate (RCA) content and fibre characteristics on the flexural response of steel fibre recycled aggregate concrete (SFRAC). A general factorial design was adopted with RCA(%) and fibre factor (FF) (product of the fibre volume fraction, aspect ratio, and bond efficiency factor) as variables. RCA levels of 0%, 50%, and 100% and FF levels of 0, 0.15, 0.20, 0.30, 0.32, 0.40, and 0.64 were considered. Mechanical properties evaluated include compressive strength, splitting tensile strength, flexural strength, residual flexural strength, and toughness. Results were analysed using main effect, interaction, and contour plots, along with analysis of variance table. Subsequently, a predictive model was proposed for SFRAC mechanical properties. The interaction between RCA and FF showed a statistically significant influence on flexural response but had an insignificant effect on compressive and splitting tensile strengths. The proposed predictive model for SFRAC properties showed good agreement with experimental results.