Physical, mineralogical, thermal, and mechanical properties of aerogel-incorporated concrete exposed to elevated temperatures

This paper investigated the physical, mineralogical, thermal, mechanical, and microstructural performances of concretes with four aerogel contents (i.e., 0, 5, 10, and 20 vol %) and after exposure to elevated temperatures (i. e., 200, 400, 600, 800, and 1000 degrees C). Mechanisms both of the heat-induced degradation and of the aerogel in mitigating the degradation of concrete were unveiled. Specimens after 200 degrees C exposure bear the same mineralogical compositions as those at 20 degrees C. After being exposed to 400 degrees C and 600 degrees C, portlandite disappeared. Dolomite and C-S-H still occurred after 800 degrees C exposure whereas disappeared after 1000 degrees C exposure. The residual strength of specimens decreased with an increase in the exposure temperature, except for the unexpectedly elevated ones after 400 degrees C exposure. Incorporating aerogel into specimens alleviated the strength loss after exposure to elevated temperatures, especially after 200-600 degrees C exposure. For instance, the strength losses of A0, A5, A10, and A20 after 600 degrees C exposure are 39.4, 39.1, 25.9, and 19.1%, respectively. Aerogel maintained its 3D nano-structure after 400 degrees C exposure; their thermal insulation properties remained functional. The heat flow was significantly retarded while meeting aerogel particles in the concrete. After 600 degrees C exposure, the gradual fusion of aerogel thickened the particle skeleton, and enhanced the stiffness and strength of the skeleton, making the aerogel-incorporated concrete resist higher loads than the control concrete. The sintering properties of aerogel play a vital role in mitigating the heat-induced degradation of concrete.

Automated summary

This paper investigated the effects of different aerogel contents in concrete and exposure to elevated temperatures on its physical, mineralogical, thermal, mechanical, and microstructural performances. The study revealed the mechanisms of heat-induced degradation and how aerogel mitigates the degradation. Incorporating aerogel into concrete alleviated the strength loss after exposure to high temperatures, with the most significant effect observed after exposure at 200-600 degrees C. The sintering properties of aerogel played a crucial role in mitigating the heat-induced degradation of concrete.