高温后玄武岩纤维增强混凝土的动态力学特性

Dynamic mechanical properties of basalt fiber reinforced concrete after elevated temperatures

为研究温度、加载速率、纤维掺量对玄武岩纤维增强混凝土(BFRC)动态压缩强度和冲击韧度的影响,利用100mm分离式霍普金森压杆(SHPB)装置,对经历不同温度作用后的BFRC进行冲击加载实验。结果表明:高温后BFRC的动压强度及冲击韧度在同一温度下随平均应变率的上升近似线性增大;温度的升高总体上导致BFRC在同一加载速率下的动压强度及冲击韧度减小、应变率敏感性减弱;同一工况下,BFRC的动压强度和冲击韧度较素混凝土普遍提高,且当纤维体积掺量为0.2%时强韧化效果相对最佳。由此可见,高温后BFRC的冲击压缩特性受温度、加载速率、纤维掺量的综合作用影响,掺入玄武岩纤维可以有效降低高温后BFRC的损伤劣化程度。

To investigate the influences of temperature, impact velocity and fiber volumetric fraction on dynamic compressive strength and impact toughness of basalt fiber reinforced concrete （BFRC）, dynamic compressive experiments were carried out on BFRC after different elevated temperatures by using a 100 mm diameter split Hopkinson pressure bar （SHPB） equipment. The results demonstrate that the dynamic compressive strength and impact toughness increase approximately linearly with the increase of average strain rate under the same temperature. At a fixed impact velocity, the rising of temperature results in a decrease in dynamic compressive strength and impact toughness as well as their strain rate sensitivities. For a given working condition, the dynamic compressive strength and impact toughness of BFRC are generally higher than those of plain concrete. The strengthening and toughening effect are relatively the best when the fiber volumetric fraction is 0.2%. Consequently, changes in dynamic compressive properties of BFRC after elevated temperatures are the combining effects of temperature, impact velocity and fiber volumetric fraction. The adding of basalt fiber can significantly decrease the thermal deterioration of BFRC.