基于热裂纹演化的玻化微珠保温混凝土渗透性能分析

Permeability analysis of glazed hollow beads insulation concrete based on thermal crack evolution

为了改善火灾后混凝土结构耐久性退化问题,利用玻化微珠(GHB)的高热稳定性对混凝土耐高温性能进行提升,通过电通量法对高温后玻化微珠保温混凝土(GIC)的抗氯离子侵蚀性能进行测试,并结合混凝土试件热裂纹演化特征对其抗氯离子侵蚀性能劣化规律进行分析.结果表明:GHB的掺加显著改善了高温后混凝土抗氯离子渗透能力退化问题,与同强度等级的普通混凝土(NC)和硅灰混凝土(SFC)相比,掺加GHB后混凝土的电通量分别降低了约54.15%、32.69%.结合各试件热裂纹演化规律,认为这归因于GHB和硅灰对混凝土密实性的提高,以及GHB对混凝土抗高温损伤造成的积极影响.在此基础上,通过考虑热裂纹演化特征、GHB和硅灰的影响,建立了高温环境氯离子渗透性预测模型.

The high thermal stability of glazed hollow bead(GHB) was used to improve the high temperature resistance of concrete, in order to improve the durability degradation of concrete structures after fire. The antichloride ion penetration of glazed hollow beads insulation concrete(GIC) exposed to high temperature was tested through the electric flux method. Meanwhile, combined with the thermal crack evolution characteristics, the deterioration law of its resistance to chloride ion corrosion was analyzed. Results showed that the application of GHB significantly improved the degradation of the chloride ion penetration resistance of concrete after high temperature exposure. Compared with normal concrete(NC) and silica fume concrete(SFC) of the same strength grade, the electric flux of concrete with GHB after high temperature exposure was reduced by about 54.15% and32.69%, respectively. Combined with the thermal cracks evolution characteristic of concrete, it was believed that this was attributed to the strengthening effect of GHB and silica fume on the compactness of concrete, and the positive contribution of GHB to thermal damage resistance of concrete. On this basis, the influences of thermal crack evolution, GHB and silica fume, were further considered, and a prediction model of chloride ion permeability in high temperature environment was finally established.