Impact resistance of steel fiber-reinforced self-compacting concrete (SCC) at high strain rates

The frequent or occasional impact loads pose serious threats to the service safety of conventional concrete structures. In this study, the impact-related properties of self-compacting concrete (SCC) with 0.5%, 0.75% and 1.0% steel fibers are systematically investigated with a Split Hopkinson Pressure bar (SHPB). Results show that the steel fibers with content no more than 1.0% can be successfully used to prepare SCC with good workability and greatly improved impact resistance. The impact properties including failure modes, peak stress, peak strain and elastic modulus are all significantly influenced by strain rate and steel fibers content. There exists a linear relationship between the dynamic increase factor (DIF) of steel fiber-reinforced SCC and the decimal logarithm of strain rate. Steel fiber-reinforced SCC generally presents higher DIF than that of steel fiber-reinforced normal concrete, showing a more remarkable strain rate effect. The impact toughness index (ITi) is defined to assess the impact resistance of steel fiber-reinforced SCC. The addition of steel fibers considerably increases the ITi of SCC, implying highly improved impact resistance. When 1.0% steel fibers are included, the average ITi of SCC is increased by 18.8%.