RPC构件的宏观裂缝和微观结构关系分析

Relationship of macro cracks and microstructure of RPC component

为了研究活性粉末混凝土(RPC)构件良好的内部结构组织,分别对不同温度下的3根RPC梁进行静载试验,观察其裂缝的开展情况.利用扫描电子显微镜(SEM)对活性粉末混凝土的微观结构进行研究分析.结果表明:高温养护的RPC更具有良好的内部结构组织,在同级荷载下,高温养护的RPC构件比常温养护的裂缝开展宽度相对小些;RPC中的水泥水化产物中主要的是C-S-H凝胶、其次是Ca(OH)2,没有发现钙矾石等其他水化产物;RPC中没有粗骨料,颗粒之间没有明显的界面过渡区,所以抗裂性更好;钢纤维的加入,填充了RPC的内部缺陷,减少了微裂缝数量,提高了RPC的界面强度.

To investigate the internal structure of reactive powder concrete （ RPC）, the static load tests of three RPC beams were conducted at different temperatures to observe the cracks. The microstruetures of RPC were determined by scanning electron microscopy （SEM）. The results show that under the same load, RPC component has good internal structure at high curing temperature with smaller crack widths than those at normal maintenance temperature. RPC cement hydration products are mainly CSH gel with some Ca （OH）2, and no ettringite or other hydration product is found. There is no coarse aggregate in RPC without transition region interface among particles, and the crack resistance is good. The internal defects of RPC are partly filled by steel fiber to reduce microcracks and improve RPC interface strength.