Description
Strengthening of reinforced concrete (RC) structures using near surface mounted (NSM) carbon fiber reinforced polymer (CFRP) technique is exhibited as effective and promising technology. However, having epoxy adhesive as the binding agent between the CFRP laminate and concrete substrate presents a serious drawback due to its low glass transition temperature (GT), which when exceeded, the epoxy adhesive loses its mechanical strength. This study focuses on optimizing a fly ash (FA) geopolymer adhesive as an alternative to epoxy. Several mixes with different constituent proportions have been investigated for their residual compressive strength and volume change at different firing periods. One mix was quenched in water to introduce and evaluate thermal shock impacts. The results demonstrate that the highest compressive strength at ambient temperature and the lowest volume change at elevated temperatures were recorded by the mix with the lowest SiO2/K2O. Mixes with higher activator alkali content achieved the highest residual compressive strength and exhibited expansion at elevated temperatures. Furthermore, the geopolymer exposed to water quenching recorded a slight decrease in both residual compressive strength and volume in comparison with samples cooled naturally. Overall, the findings suggest that employing potassium-based geopolymers in NSM CFRP applications could offer significant improvements in terms of advancing thermomechanical performance.
