Flexural–Shear Performance of Ternary Blended Geopolymer Concrete Beams with FRP Reinforcements for Sustainable Infrastructure

Geopolymer concrete (GPC) has emerged as a sustainable alternative to Portland cement by utilizing industrial by-products and lowering carbon emissions. However, its inherent brittleness and low ductility limit structural applications. This paper focused on the flexural-shear behaviour of ternary blended GPC, which was made of fly ash, GGBFS, and lime sludge. To counteract with the mechanical weaknesses of ternary GPC and make more suitable for structural applications, hooked-end steel fibers and carbon fiber reinforced polymer (CFRP) bars are proposed to be used as the reinforcements instead of stirrups in the shear span. Twenty-six beams with different shear span to depth ratios (1.5, 2.0, and 2.25) were tested under a four-point bending, supplemented by tests on fresh state, mechanical properties, durability, micro-structure and costs. Finite element models of GPC beams have been successfully created using ABAQUS software and validated against experimental results. Experimental results have shown that steel fibers can effectively improve the ductility and crack propagation, and CFRP could efficiently enhance stiffness of GPC. In addition, by hybridizing steel fiber and CFRP bar the GPC beams can possess well balanced mechanical performance. It can be found that, the ternary GPC reinforced with FRP would be one of the suitable green building materials.