Flexural Behaviour of Combined FA/GGBFS Geopolymer Concrete Beams after Exposure to Elevated Temperatures

As a promising alternative to OPC concrete, geopolymer concrete has been investigated and has demonstrated superior mechanical performance. Studying the thermal behaviour on the scale of a structural element is significant for introducing a new material to engineering applications. Four geopolymer concrete beams and four OPC concrete counterparts with the same reinforcement structure and similar concrete strength were subjected to three different heating cases at the rate of ISO834. The experimental results showed that the geopolymer concrete beams underwent a colour change, severe cracking, and no spalling after the exposure. While under load, the geopolymer concrete specimens exhibited a lower crack resistance and flexural stiffness. The residual load capacities were 110%, 107%, and 90% of the ambient specimen for the geopolymer concrete samples and 103%, 97%, and 80% for the OPC concrete samples. To some extent, the geopolymer concrete beams achieved superior fire endurance compared to their OPC concrete counterparts.