Influence of high temperature on the compression and bending properties of AASCM

Alkali-activated slag cementitious materials (AASCM) with manufactured sand can effectively utilise industrial waste slag and reduce river sand consumption. Steel fibres can effectively improve the mechanical properties of AASCM. Therefore, this study investigated the influence of steel fibre and aggregate type on the compression and bending properties of AASCM after high-temperature treatment. The results showed that the mass loss rate, compressive strength, and flexural strength loss rate of AASCM with manufactured sand were higher than those with natural river sand at different temperatures. Steel fibres can increase the mass loss rate of AASCM; however, the influence of the steel fibre content on the mass loss of AASCM was not apparent. When the temperature was lower than 600°C, the compressive and flexural strength of AASCM effectively was increased by steel fibre, while for temperatures higher than 800°C, the mechanical properties of AASCM did not improved owing to the oxidation failure of steel fibre. Microstructure analysis showed that the number of microcracks in the AASCM increased owing to the high silicon content of the manufactured sand, and the bond property between the steel fibres and cementitious materials decreased with an increase in temperature.