A Heravi Ali, Mosig Oliver, Tawfik Ahmed, Curbach Manfred, Mechtcherine Viktor
Institute of Construction Materials, TU Dresden, 01062 Dresden, Germany.
Institute of Concrete Structures, TU Dresden, 01062 Dresden, Germany.
Materials (Basel). 2020 Oct 12;13(20):4514. doi: 10.3390/ma13204514.
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 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.
应变硬化水泥基复合材料（SHCC）在直接拉伸载荷下的延性行为使其在需要高能量耗散的应用中成为有前景的解决方案，例如在地震、弹丸撞击或爆炸中。然而，SHCC由于多重开裂而具有的卓越拉伸延性并不一定意味着其具有压缩和剪切延性。为了表征SHCC在与上述高速加载场景相关的冲击压缩和剪切载荷下的行为，本文采用分离式霍普金森压杆法研究了一种特定的SHCC及其组成部分水泥基基体的性能。对于压缩试验，使用了长径比（l/d）为1.6的圆柱形试样。所选试样长度使得在准静态和冲击加载条件下具有相似的破坏模式，这对于可靠比较观察到的抗压强度是必要的。冲击试验在分离式霍普金森压杆（SHPB）上进行，在破坏瞬间应变率达到110 s⁻¹。对于剪切试验，为分离式霍普金森拉杆（SHTB）开发了一种特殊的适配器。该适配器使得能够利用SHTB中产生的拉伸波对平面试样进行冲击剪切试验。结果表明，SHCC的抗压强度和抗剪强度的动态增强因子（DIF）分别为2.3和2.0。与未增强的组成基体相比，SHCC的抗压强度绝对值较低。相反，在剪切载荷下，SHCC表现出比未增强基体更高的抗剪强度。
