Compression and bending of alkali-activated slag cementitious materials at high temperature

Abstract

Alkali-activated slag cementitious material (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, in this study, the influence of steel fibres and aggregate type on the compression and bending properties of AASCM after high-temperature treatment was investigated. The results show 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 was effectively increased by steel fibres, while, for temperatures higher than 800°C, the mechanical properties of AASCM did not improve, owing to the oxidation failure of steel fibres. 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.