Study on physical and mechanical properties of aerogel powder-glass microspheres cement-based composites before and after high temperature

This study aims to investigate the performance of aerogel powder–glass microsphere cement-based composites (AGCC), with a focus on their thermal insulation, mechanical properties, and high-temperature resistance. AGCC specimens were prepared by incorporating equal volume fractions (5%, 10%, 20%, and 30%) of aerogel powder and glass microspheres, and their properties were tested. Results indicate that the pore structure of AGCC evolves from a dense morphology to a mesoporous system with increasing admixture content, thereby enhancing thermal insulation. Thermogravimetric analysis reveals that a moderate addition of aerogel and glass microspheres (10–20%) improves thermal stability, whereas higher content (30%) lead to greater mass loss. The thermal conductivity of AGCC decreases with increasing content, reaching as low as 0.32 W/(m·K) for AGCC-30%, demonstrating excellent insulation performance. However, the incorporation of aerogel and glass microspheres adversely affects the mechanical properties, particularly at higher content, the compressive strength of AGCC-20% decreases by 60% compared with the unincorporated state. Under elevated temperatures, both compressive and flexural strengths deteriorate significantly, with the compressive strength of AGCC-30% retaining only 39% of its room-temperature value at 400 °C. Scanning electron microscopy further reveals morphological differences between AGCC before and after high-temperature exposure, providing microstructural evidence for the observed degradation in mechanical performance. The AGCC prepared in this study is suitable for non-load-bearing structural applications that require thermal insulation performance. • A cement-based composite (AGCC) containing both aerogel and glass microspheres was fabricated. • The thermal conductivity of AGCC decreased with increasing aerogel-glass microsphere content. • The mechanical properties of AGCC at room temperature and after high temperatures were investigated.