Stress–strain model of steel fibre-reinforced alkali-activated slag cementitious material after high-temperature exposure

Abstract

Steel fibres can reduce the shrinkage of alkali-activated slag cementitious material (AASCM) and improve their strength. Therefore, it is of great significance to accurately predict the stress–strain relationship of steel fibre-reinforced AASCM after exposure to high temperatures to promote this green building material. The effects of temperature and steel fibres on the axial compressive strength, elastic modulus, peak compressive strain, and stress–strain curve of the AASCM were analysed. The test results showed that after exposure to high temperatures, there were two compression failure modes of AASCM: tensile failure and shear failure. After exposure to 200 °C, 400 °C, 600 °C and 800 °C, the average strength loss rate of AASCM was 38.8%, 58.2%, 75.8% and 90.1%, respectively. Below 600 °C, the steel fibre has a positive effect on the compressive strength, elastic modulus and peak compressive strain of AASCM, with the optimal volume fraction being 1.5%. Based on the test data, the existing models are compared and analysed. And a model for predicting the compressive strength, peak strain, elastic modulus and stress-strain relationship of steel fibre-reinforced AASCM was proposed.