Study on mechanical properties and microstructure of aluminate cement-based materials incorporating recycled brick powder after exposure to elevated temperatures

Abstract

The mechanical properties of aluminate cement-based materials (A-CM) that partially replaced by recycled brick powder (RBP) after exposure to elevated temperatures were studied in this paper. A total of 72 prism specimens were prepared, and the main parameters included RBP replacement ratio (0%, 5%, 10%, and 15%) and exposure temperature (20 °C, 200 °C, 400 °C, 600 °C, 800 °C, and 1000 °C). The compressive and flexural tests of specimens after exposure to elevated temperatures were conducted, and the phase of hydration products and the microstructure of hardened cement paste were systematically analyzed by microscopic tests. The influence mechanism of RBP on the mechanical properties of A-CM before and after high temperatures was revealed. Results showed that the A-CM specimen with RBP replacement ratio of 5% presented the highest compressive and flexural strength at any exposure temperature. The compressive strength of specimens with the same RBP replacement ratio first increased and then decreased with the increase of exposure temperatures, and the highest compressive strength was obtained after exposure to 200 °C. While the flexural strength of specimens at any RBP replacement ratio decreased all the time with the increase of exposure temperature. Moreover, the explosive spalling of A-CM specimens after exposure to 1000 °C could be inhibited when the RBP replacement ratio exceeded 10%. Finally, a calculation method that considered the effect of RBP replacement ratio to predict the compressive and flexural strength of A-CM specimens after exposure to elevated temperatures was proposed and validated.