Study on dynamic mechanical properties of steel fiber reinforced reactive powder concrete after high temperature

This paper focuses on the dynamic mechanical properties of steel fiber reinforced reactive powder concrete (SFRPC) after high temperatures. Three kinds of reactive powder concrete (RPC) specimens with steel fiber volume fractions of 1%, 2% and 3% were prepared, and the impact compression tests of specimens treated at different temperatures (25℃, 200℃, 400℃, 600℃, 800℃) were carried out by Φ50 mm split Hopkinson pressure bar (SHPB). Accordingly, the dynamic stress-strain curves and various dynamic mechanical properties are obtained. Based on the modified Z-W-T constitutive model, the dynamic damage constitutive model of steel fiber reinforced RPC considering heating temperature and fiber content are derived to compare with the experimental results. The results show that the steel fiber has a significant effect on improving the deformation resistance and energy absorption capacity of RPC. The dynamic compressive strength shows strong strain rate dependence, and increase approximately linearly with the increase of average strain rate. High temperature has an obvious effect on the properties of RPC materials. The dynamic compressive strength, toughness and dynamic elastic modulus of RPC increase first and then decrease with the boundary of about 400℃. When the temperature reaches 800℃, the reinforcing effect of steel fiber is basically lost. The dynamic damage constitutive model curves coincide quite well with the stress-strain curves obtained from the test.