Experimental investigation of rectangular air-cured geopolymer concrete columns reinforced with GFRP bars and stirrups

Glass fiber-reinforced polymer (GFRP) bars in construction are increasing in popularity due to their excellent corrosion resistance, high tensile strength to weight ratio, and low maintenance. Geopolymer is a modern cementitious material that is known for its corrosion resistance and low carbon footprint. Combining the two could produce a green yet durable composite material that can be applied to aggressive environments such as Australia's coastal zones. This paper experimentally investigates the load-moment interaction of GFRP-reinforced air-cured geopolymer concrete columns. The behavior of reinforced geopolymer concrete under combined loading were studied with 11 half-scale specimens. Three different stirrup spacings (75, 150, and 250 mm) were examined. Effective confinement was achieved by reducing the stirrup spacing such that high strains were measured in the concentric columns with closely spaced (75 mm) stirrups. A comparison between the experimental data and international design codes showed that such codes were conservative when ignoring the compressive strengths of the longitudinal GFRP bars. The experimental results were better represented when the compressive strengths of the bars were included; on average, the GFRP-reinforced geopolymer concrete columns exhibited 10.8% increase in strength with respect to unreinforced concrete sections.