含粗骨料超高性能混凝土力学性能研究

针对超高性能混凝土(UHPC)胶凝材料用量大，前期成本高等问题，通过在UHPC体系中掺入粗骨料，用河砂代替石英砂，成功制备了具有优异力学性能的含粗骨料UHPC,并通过试验研究了粗骨料掺量以及钢纤维几何参数对含粗骨料UHPC力学性能的影响.结果表明：随着粗骨料掺量的增加(0~800 kg/m3)，UHPC抗压强度先增加后下降，静力受压弹性模量几乎呈线性增加；粗骨料掺量为0~400 kg/m3时，UHPC抗弯拉强度和初裂强度变化较小，粗骨料掺量为400~800 kg/m3时，UHPC抗弯拉强度和初裂强度明显下降；随着粗骨料掺量的增加(0~800 kg/m3)，UHPC弯拉荷载-挠度曲线变化明显，弯曲韧性明显下降，但均存在应变硬化过程；随着钢纤维长度增加，UHPC的抗压强度、抗弯拉强度以及弯曲韧性均增加，但是静力受压弹性模量和初裂强度变化较小.
Due to the problems of large amount of cementitious material and high cost of Ultra High Performance Concrete (UHPC), the UHPC system was mixed with coarse aggregate and river sand instead of quartz sand, and the preparation of UHPC with coarse aggregate is successful resulting in excellent mechanical properties. Meanwhile, the effects of the coarse aggregate content and geometric parameters of the steel fiber on the mechanical properties of the UHPC with coarse aggregate were studied. The results showed that, with the increase of coarse aggregate content (0~800 kg/m3), the compressive strength of UHPC increased firstly and then decreased, the elastic modulus increased almost linearly. When the content of coarse aggregate was in 0~400 kg/m3, the flexural strength and initial crack strength of UHPC changed little, while when the content of coarse aggregate was 400~800 kg/m3, the flexural strength and initial crack strength of UHPC decreased obviously. With the increase of the content of coarse aggregate (0~800 kg/m3), the flexural load-deflection curve of UHPC was obviously changed, and the flexural toughness decreased obviously, but a strain- hardening process was observed. With the increase of the length of steel fiber, the compressive strength, flexural strength and flexural toughness of UHPC increased, but the static compression modulus and initial crack strength of UHPC changed little.