纤维矿渣微粉混凝土高温中的劈拉性能

通过高温（200～800℃）劈拉试验,测定124个纤维矿渣微粉混凝土（FRC-GGBFS）试件的劈拉强度和荷载—横向变形曲线,探讨温度、矿渣掺量、钢纤维掺量和聚丙烯纤维掺量对FRC-GGBFS的高温中劈拉强度和变形的影响,并通过不同温度下扫描电镜分析,探讨FRC-GGBFS的高温劣化过程。结果表明：随温度升高,FRC-GGBFS劈拉强度不断劣化,劈拉荷载—横向变形曲线渐趋扁平,韧性显著下降;矿渣微粉掺量为40%时,其对混凝土的高温中劈拉性能的改善最为显著;钢纤维显著提高了FRC-GGBFS的高温中劈拉强度和韧性;聚丙烯纤维能有效防止高温爆裂,其掺量为0.9 kg/m3时对FRC-GGBFS的高温中劈拉性能有明显改善。最后,建立了考虑温度、钢纤维体积率等影响的FRC-GGBFS高温中劈拉强度计算模型。

Splitting Tensile Properties of Fiber Reinforced Ground Granulated Blast Furnace Slag Concrete at High Temperatures

Through the splitting tensile tests of fiber reinforced ground granulated blast furnace slag concrete (FRC-GGBFS) at high temperatures (200–800 ℃), the splitting tensile strength and splitting tensile loading–transverse deformation curve of 124 samples were measured. The effects of temperature, replacement rate of cement by slag powder, steel fiber content, polypropylene fiber content on the splitting tensile strength and deformation of FRC-GGBFS were investigated. The deterioration processes of FRC-GGBFS at different temperatures were analyzed by scanning electron micrograph. The splitting tensile strength of concrete deteriorated, the splitting tensile loadingtransverse deformation curves appeared more flat and the toughness of FRC-GGBFS decreased as the temperature increased. The addition of GGBFS, especially at the content of 40%, favored the splitting tensile properties of concrete at high temperatures. Steel fiber could increase the splitting tensile strength and toughness of FRC-GGBFS at high temperatures. Polypropylene fiber could prevent the spalling and cracking phenomena, providing the superior splitting tensile properties of FRC-GGBFS at high temperatures at the content of 0.9 kg/m 3 . A analytical model for the splitting tensile strength of FRC-GGBFS was proposed.