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该文采用Ф80 mm的分离式霍普金森压杆装置,研究了纳米改性后的UHTCC(ultra high toughness cementitious composites)在高速冲击压缩应力状态下的力学响应,并与常规UHTCC材料、钢纤维混凝土进行了对比。试验得到了各组材料在准静态和动态共计4组应变率(2.36×10~(-5) s~(-1)、120 s~(-1)、160 s~(-1)、200 s~(-1))下的准静态压缩强度及冲击压缩应力-应变曲线,并计算了各组试件的耗能能力。为了进一步优化材料的抗冲击性能,该文还研究了纳米改性后的UHTCC基体中钢纤维和PVA纤维的混杂效果。试验结果表明:5组材料均具有应变率敏感性,峰值应力和耗能能力随着应变率的增大而上升;经过纳米改性后的UHTCC材料冲击压缩力学强度及耗能能力明显提高;在冲击荷载下,钢纤维和PVA纤维产生正混杂效应,提高钢纤维掺量可以强化UHTCC的抗冲击能力;应变率的大小和钢纤维的掺量之间的关系影响了动态峰值应力的提升。
In this paper, the mechanical response of ultrahigh toughness cementitious composites (UHTCC) under high-speed impact and compression stress was studied using a split Hopkinson pressure bar (Ф80 mm) and compared with conventional UHTCC materials, steel fiber reinforced concrete Made a contrast. In the quasi-static and dynamic tests, the strain rates of four groups (2.36 × 10 -5 s -1, 120 s -1, 160 s -1, 200 s -1) ~ (-1)) and the compressive stress-strain curves of impact-compression, and the energy dissipation capacity of each specimen was calculated. In order to further optimize the impact resistance of the material, this paper also studied the hybrid effect of steel fiber and PVA fiber in the nano-modified UHTCC matrix. The results show that the five materials have the strain rate sensitivity, the peak stress and energy dissipation capacity increase with the increase of the strain rate. The impact strength and energy dissipation capacity of the nano-modified UHTCC material increase obviously. Under the impact load, the steel fiber and the PVA fiber have a positive hybrid effect. Increasing the steel fiber content can enhance the impact resistance of the UHTCC. The relationship between the strain rate and the steel fiber content affects the dynamic peak stress.