Behaviour of Steel Fibre Reinforced Geopolymer Concrete Deep Beams Under the Effect of Elevated Temperatures

Alkali-activated or geopolymer concrete has become popular as a promising substitute for ordinary Portland cement (OPC) concrete. Geopolymer concrete has a lower environmental impact than OPC, which has made it a favourable research option. Geopolymer binders can be manufactured from by-product/waste materials (e.g., slag, fly ash, red mud, etc.) or natural materials (e.g., kaolin or pozzolans). Previous geopolymer research has been extensively focused on the material level, with limited studies of the behaviour of the structural components. Therefore, the shear behaviour of steel fibre reinforced concrete deep beams synthesized from metakaolin and fly ash was investigated in the present study. Three deep beams were exposed to an elevated temperature of 600 degrees C and tested under four-point bending configuration. The primary variable was the steel fibre content (0, 0.35 and 0.7%). It was observed that the addition of steel fibres contributed to the compressive strength after heat exposure, with attained compressive strengths of 16.3, 20.7 and 19.1 MPa, respectively, for concrete with 0, 0.35 and 0.7% steel fibres. The shear strength after exposure 600 degrees C was 141.2, 143.8 and 152 kN, respectively, for concrete with 0, 0.35 and 0.7% steel fibres, indicating a negligible effect of steel fibres in increasing the shear strength of metakaolin-fly ash based geopolymer concrete after heat exposure.