【作者】 吴思远； 吴守军； 张博； 王正中；

【Author】 Wu Siyuan;Wu Shoujun;Zhang Bo;Wang Zhengzhong;College of water resources and architectural engineering, Northwest A&F University;

【机构】 西北农林科技大学水利与建筑工程学院；

【摘要】 本文针对性制作了适合环境扫描电镜观察的混凝土小样品,研究了高温作用后混凝土内部,特别是骨料/浆体界面区和浆体的微观变化,并结合能谱分析浆体元素变化。发现:原始素混凝土水泥浆体密实、无明显孔洞,水泥浆体和骨料之间粘合紧密,观察不到裂缝;200℃时水泥浆体出现小孔,随温度升高孔洞长大,骨料与水泥浆体粘合面出现裂缝,温度升高粘合面裂纹逐渐扩展为彼此连贯的整体网状裂纹;600℃时水泥浆体局部出现较大的粉状颗粒,水泥出现浆体分解析晶。高温作用前后,素混凝土的元素组成基本没有变化,但水泥的主要组成Ca、O、Mg、Si、Al等元素含量发生明显变化。更多还原

【Abstract】 In this paper, small concrete samples which are suitable for observing with the environmental scanning electron microscope were prepared and exposed to different high temperatures. The microstructure changes of the concrete interior, especially which of the aggregate/cement paste interface area and the paste after high temperatures were studied. And the elements composition changes of the cement paste were studied using energy spectrum analysis. It is found that the original cement paste is dense and free of obvious holes. The cement paste and the aggregate are bonded tightly, and no cracks are observed. At 200℃, small holes are present in the cement paste and microcracks are occurred at the bonding interface of the aggregate/cement paste.With the temperature increasing, the small holes are growing up and the microcracks are gradually expanded into a coherent whole network crack. At 600℃, some big powder particles are locally formed in the cement paste and there are decomposition and devitrification of the cement paste.Before and after the high temperature, the element compositions of the plain concrete had no change, but the major elements such as Ca, O, Si, Mg, Al in cement changed obviously.更多还原