高温后活性粉末混凝土微观结构分析

试验分析了高温后活性粉末混凝土（RPC）的外观、质量损失和抗压强度随温度的变化情况;利用扫描电镜（SEM）研究了经历不同高温后的RPC微观结构变化和物相组成.结果表明：经历温度低于400oС时,水泥水化反应和火山灰反应互相促进,RPC微观结构得到改善,抗压强度较常温时有所提高;经历温度为400～800oС时,C-S-H凝胶由连续块状变为尺寸较小的分散相,钢纤维与基体粘结界面处的裂纹逐渐形成并扩展,聚丙烯纤维融化后的孔道加剧了RPC的内部缺陷,RPC微观结构不断恶化,抗压强度逐渐降低.

Microstructure analysis of reactive powder concrete after exposed to high temperature

The appearance,mass loss and cube compressive strength of reactive powder concrete(RPC) after exposed to different temperatures were introduced,and its microstructure and phase composition were studied by scanning electron microscopy(SEM) technique after exposed to high temperatures.The results show that,after exposed to less than 400 ℃,the cement hydration and the pozzolanic reaction promotes each other,which improves the microstructure of RPC so the compressive strength of RPC has increased compared with that of unheated;when exposed to 400~800 ℃,with the temperature elevated the C-S-H gel shifts from continuous block like form to dispersed phase,and the cracks at the bonding interface of steel fiber and the matrix come into being and expand gradually.The melting channels of polypropylene fibers exacerbate the internal defects of RPC,so the microstructure of RPC deteriorates constantly and the compressive strength decreases gradually.