纤维矿渣微粉混凝土高温中的劈拉性能

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

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。

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 con-tent 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 loading-transverse deformation curves appeared more flat and the toughness of FRC-GGBFS decreased as the tem-perature 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.Poly-propylene 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/m3.A analytical model for the splitting tensile strength of FRC-GGBFS was proposed.