The ductile behavior of strain-hardening cement-based composites (SHCC) under direct tensile load makes them promising solutions in applications where high energy dissipation is needed, such as in earthquakes, impacts by projectiles, or blasts. However, the superior tensile ductility of SHCC due to multiple cracking does not necessarily point to compressive and shear ductility. As an effort to characterize the behavior of SHCC under impact compressive and shear loading relevant to the aforementioned high-speed loading scenarios, the paper at hand studies the performance of a particular SHCC and its constituent, cement-based matrices using the split-Hopkinson bar method. For compression experiments, cylindrical specimens with a length-to-diameter ratio (l/d) of 1.6 were used. The selected length of the sample led to similar failure modes under quasi-static and impact loading conditions, necessary to a reliable comparison of the observed compressive strengths. The impact experiments were performed in a split-Hopkinson pressure bar (SHPB) at a strain rate that reached 110 s⁻¹ at the moment of failure. For shear experiments, a special adapter was developed for a split-Hopkinson tension bar (SHTB). The adapter enabled impact shear experiments to be performed on planar specimens using the tensile wave generated in the SHTB. Results showed dynamic increase factors (DIF) of 2.3 and 2.0 for compressive and shear strength of SHCC, respectively. As compared to the non-reinforced constituent matrix, the absolute value of the compressive strength was lower for the SHCC. Contrarily, under shear loading, the SHCC demonstrated higher shear strength than the non-reinforced matrix.

The paper presents a testing facility, which enables the characterization of the shear behavior of cementitious composites under quasi-static and impact shear load. The device was designed by means of an extensive numerical parameter study on device geometry, materials and wave propagation, as well as specimen configurations and boundary conditions. The new shear testing device was integrated into a gravity-driven Split-Hopkinson tension bar (SHTB) for shear impact experiments and in a hydraulic testing machine for quasi-static shear experiments on strainhardening cement-based composites (SHCC). The shear response of the SHCC specimens was derived from the force obtained on the transmitter bar in the SHTB accompanied by high-speed optical measurements, which also enabled an accurate analysis of the crack-opening displacements and fracture modes by means of Digital Image Correlation (DIC).