Uniaxial compression performance and stress-strain constitutive model of the aluminate cement-based UHPC after high temperature

In this study, a total of 72 prism specimens were manufactured to investigate the steel fiber volume fraction and exposure temperature on the uniaxial compression performance of the aluminate cement-based ultra-high performance concrete (A-UHPC). The main uniaxial compression performances of the A-UHPC after high temperature were examined, including the apparent characteristic, mass loss, failure mode, compressive strength, peak strain, initial elastic modulus and compressive stress-strain curve. As the exposure temperature increased, the failure mode of the non-fiber specimen showed a trend of transition from brittleness to ductility, the uniaxial compressive strength first increased and then decreased and the peak strain gradually increased. However, the initial elastic modulus continued to decrease. Subsequently, the calculation formulas of the uniaxial compressive strength, peak strain and elastic modulus considering the influence of temperature were proposed through regression analysis, and the uniaxial compression stress-strain constitutive model of the A-UHPC with 3% volume steel fiber was established and verified. Finally, the deterioration mechanism of the A-UHPC after high temperature was revealed by SEM for microscopic phase tests.