FRP reinforced recycled aggregate concrete columns under static loading: a comprehensive review with machine learning perspectives

Abstract

This review paper investigates the behaviour of fibre-reinforced polymer (FRP)-reinforced recycled aggregate concrete (RAC) columns under static loading conditions. The adoption of RAC, which uses recycled materials, is essential for sustainable construction, but its reduced mechanical properties pose challenges. To enhance RAC structural performance, FRP composites are applied to improve compressive strength, ductility, and energy dissipation capacity. FRP confinement mechanisms, including external wrapping and hoop reinforcement, provide lateral support, effectively increasing the axial load capacity of RAC columns and delaying failure mechanisms such as concrete crushing and FRP debonding. This paper examines over 100 studies, focusing on key parameters such as FRP material type (carbon, glass, aramid), the confinement effect of FRP, and the recycled aggregate replacement ratio. The review finds that FRP reinforcement significantly enhances RAC columns' compressive strength and ductility, with axial load capacity improving by up to 88.7% and energy dissipation increasing by 24.5%. However, the interaction between FRP and RAC remains complex, with increased recycled aggregate replacement ratios resulting in a decrease in compressive strength by approximately 19% at 100% replacement. Despite the positive outcomes, challenges such as long-term durability, environmental impact, and cost-effectiveness remain. The research identifies gaps, including the need for more studies on long-term performance, life-cycle assessments (LCA), and the development of predictive models for FRP-RAC columns. Key conclusions highlight that FRP reinforcement can boost column strength and ductility, but further investigation into environmental impacts and long-term behaviour is necessary. The review emphasizes future research directions to optimize FRP-RAC column design and sustainability.