高温作用后矿渣微粉纤维混凝土的微观结构

Microstructure of fiber reinforced concrete with slag power after effect of high temperatures

通过对扫描电镜照片的对比分析,探讨了矿渣微粉纤维混凝土经受不同高温作用后,水泥浆体、骨料与水泥浆体界面过渡区内的水化硅酸钙C-S-H凝胶、钙矾石AFt和氢氧化钙Ca(OH)2等水泥水化物形貌、状态、数量及孔隙与裂缝的变化情况.结果表明,经历不同程度的高温后,水泥浆体及界面过渡区的结构疏松程度增加,水化产物不密实,C-S-H凝胶网状结构破碎直至消失,AFt和Ca(OH)2逐步分解含量减少,骨料与水泥浆之间的粘结变得松散,裂缝逐渐扩展.混凝土中的聚丙烯纤维在160℃左右熔融逸出,形成众多相互交织的孔隙通道,缓解了其内部的蒸汽压力,有效阻止了混凝土的爆裂.

Through the comparative analysis of scanning the electron micrograph,this paper discusses the changes of fiber reinforced concrete with slag power after the effects of various high temperatures.The changes in appearance,status,number,pores and cracks of cement hydrates of C-S-H gel,AFt and Ca（OH）2,which are contained in cement paste and the interfacial transition region between aggregates and cement paste,are studied.The results show that,after the effect of various high temperatures,the loose degree of the cement paste and the interfacial transition region increases;the hydrated product is uncompacted;the networking structure of C-S-H gel breaks until dissolving,the content of AFt and Ca（OH）2 reduces gradually;the bond of aggregates and cement paste becomes loose,and the cracks extend.It also proves that the transgression of the polypropylene fiber is about 160℃,which leads to numerous interlacing pore channels that can reduce steam stress in concrete and prevent the bursting of concrete effectively.