Flexural behaviour and efficiency of CFRP-laminate reinforced recycled concrete beams: Optimization using linear weighted sum method

Abstract

The increased demand for lightweight high-performance composites has led to search for alternative reinforcement to improve the mechanical performance of conventional structures. Likewise, various research initiatives have advocated recycling of construction and demolition wastes and novel technologies to avert their generation. Owing to disadvantages of steel rebar, carbon fibre reinforced polymer (CFRP) was utilized as potential internal reinforcement in recycled concrete beam owing to its lightweight, non-corrosiveness, high-stiffness-to-weight ratio and flexibility. Our study revealed significant improvement in the mechanical performance and efficiency which is controlled by the fibre architecture. The improved mechanical properties was attributed to the Bauschinger strain-reversal effect, made possible by the effective CFRP tensile strength mobilization, its high bonded surface area and interfacial energy as well as the composite action of the multi-layered CFRP reinforcements. The best configuration (N4) revealed by the simplified linear weighted sum optimization method achieved strengthening (load) efficiency of 402.7%, ductility efficiency of 299.7%, fracture toughness efficiency of 567.1% and fracture energy efficiency of 5713.9% compared to the unreinforced control. In addition, CFRP laminate was 3.67–4.9 times more cost-effective than steel rebar in terms of fracture toughness. Therefore, CFRP-reinforced recycled concrete is recommended for cost-effective and sustainable prefabricated concrete structures.