Dynamic stress–strain relationship of steel fiber-reinforced rubber self-compacting concrete

Rubber has good elastic properties; however, its incorporation reduces the strength of concrete. Due to the high elasticity of rubber and the good crack resistance of steel fibers, the mixing of steel fibers and rubber can effectively improve the impact toughness index of concrete with sufficient strength. An impact test of steel fiber-reinforced rubber self-compacting concrete (SRSCC) was carried out using a split Hopkinson pressure bar (SHPB) in the present work, in which the strain rate ranges from 65.3 s−1 to 137.6 s−1 and steel fibers with four volume fractions of 0%, 0.5%, 1.0% and 2.0% and rubber contents with four volume fractions of 0%, 10%, 20% and 30% are considered. Experimental results revealed that, (i) the dynamic compressive strength, toughness index, stress impact factor (DIF-σ) as well as strain impact factor (DIF-ε) of SRSCC increase obviously with the increase of strain rate; (ii) with the increase of rubber content, the dynamic compressive strength decreases and the toughness index increases. When the rubber content reached 30%, the dynamic compressive strength decreased by 40–50% and the toughness index increased by 20–30%; (iii) the DIF-σ increases first and then decreases slightly with the increase of rubber content, which reaches the maximum value when the rubber content is 20%. What’s more, the effect of rubber content on DIF-σ at high strain rate is more obvious; (iv) the steel fiber content shows strengthening effects on the dynamic compressive strength and toughness index and almost has no effects on the DIF-σ and DIF-ε of SRSCC. Finally, the dynamic stress–strain relationship of SRSCC was proposed.