Low-carbon enhancement of fly ash geopolymer concrete: Lateral deformation, microstructure evolution and environmental impact

To provide a more environmentally friendly alternative to conventional cement-based concrete, the use of fly ash based geopolymer concrete (FGC) has been explored. However, FGC typically requires high-temperature curing to achieve optimal material performance, which results in significant energy consumption and carbon emissions, leading to negative environmental impacts. To address this issue, a small amount of ordinary Portland cement (OPC) has been added to FGC, facilitating its setting and hardening at room temperature. At four different ages, a series of basic mechanical properties were tested, including Poisson's ratio. At 28 days, the resulting OPC-FGC has demonstrated comparable polymerization reactions and mechanical properties to heat-cured FGC, including lateral deformation ability and compressive behavior. Microscopic tests have shown that OPC-FGC has a denser matrix and a more reasonable pore structure distribution over time than heat-cured FGC. Furthermore, a life cycle assessment has indicated that OPC-FGC has a lower negative impact than heat-cured FGC. These findings suggest that OPC-FGC can be a viable substitute for conventional cement-based concrete, providing both mechanical properties and environmental benefits in engineering applications.