Effect of SiC dosage on compressive strength, flexural strength, and bond flexural strength of geopolymer mortar at high temperature

Abstract

This paper investigates the influence of SiC dosage on the high-temperature mechanical properties (compressive strength, flexural strength, and bond flexural strength) of geopolymer mortar. The findings reveal that appropriate amount of SiC was found to improve the high-temperature mechanical properties of geopolymer mortar. Compared to the specimen without SiC, the addition of 3 wt. % SiC to the geopolymer mortar resulted in a noteworthy 14.59% increase in compressive strength at 300 °C, along with respective augmentations of 24.72% and 22.54% in flexural strength and bond flexural strength at 200 °C. Utilizing the experimental data as a foundation, a thermodynamic mathematical model was formulated, linking the strength and temperature parameters of SiC-modified geopolymer mortar. Furthermore, FTIR (Raman and Fourier transform infrared) analysis indicated that the polycondensation reaction of geopolymer mortar treated at 300 °C was promoted, and the products of displacement reaction increased, which provides a plausible explanation for the observed enhancement in compressive strength at 300 °C. Consequently, it is found that the incorporation of SiC can enhance the high-temperature mechanical properties of geopolymer mortar.