牺牲混凝土在高温作用下的损伤及机理分析  

Damage and mechanism analysis of sacrificial concrete under high temperature

作　　者：李杰青[1] 孙伟[1] 蒋金洋[1] 金祖权[2] 张巧芬[3] 李政[3] 于英俊[1] 

机构地区：[1]东南大学材料科学与工程学院,南京211189 [2]青岛理工大学土木工程学院,青岛266033 [3]中国建筑第二工程局有限公司,北京100054

出　　处：《东南大学学报（自然科学版）》2013年第3期599-603,共5页Journal of Southeast University：Natural Science Edition

基　　金：国家自然科学基金资助项目(51078081);东南大学基本科研业务业务费重大科学研究引导基金资助项目

摘　　要：为了研究牺牲混凝土的关键性能以及高温下性能演变与演变机理,采用105℃失重指标和X射线荧光分析仪测试牺牲混凝土的自由水含量和化学组成,并采用抗压强度指标、计算机断层扫描仪和扫描电镜研究了聚丙烯纤维对高温作用下牺牲混凝土强度、孔结构和微观形貌的影响.试验结果表明,制备的牺牲混凝土具有良好的流动性和力学性能,自由水的质量分数仅为4.4%,而SiO2和Fe2O3的质量分数则分别达到48.8%和30.0%,满足第三代核电站的基本要求.随温度升高,牺牲混凝土中的Fe2O3逐步还原为Fe3O4,混凝土表面逐渐疏松,同时微细裂缝和宽大裂缝增多,孔隙率最多增加了31.3%～42.8%,而900℃时牺牲混凝土抗压强度则降低为初始强度的27.1%～33.0%.聚丙烯纤维的掺加降低了牺牲混凝土的流动性和强度,但其高温残余抗压强度提高了5%～8%,且试件在高温下不爆裂.In order to study the key properties,properties evolution and evolution mechanism of sacrificial concrete（SC） under high temperatures,free water content and chemical composition of SC were investigated by weight loss under 105 ℃ and X ray fluorescence（XRF） analysis.Then,the effect of polypropylene fiber on the strength,pore structure and micro-morphology of SC under high temperatures were studied by compressive strength,computed tomography scan（CT） and scanning electron microscopy（SEM）.The experimental results show that the proposed sacrificial concrete has great fluidity and mechanical property.The mass fraction of free water content is only 4.4%,while those of SiO2 and Fe2O3 are 48.8% and 30.0%,respectively,which meets property requirements of SC used for the third generation of nuclear power plant.With the increase of temperature,Fe2O3 in sacrificial concrete is gradually reduced into Fe3O4,and concrete surface becomes loose gradually;meanwhile,the number of fine and wide cracks increase,and the porosity of SC increases by 31.3% to 42.8% maximally.The compressive strength under 900 ℃ is reduced to 27.1% to 33.0% of original strength.Although the addition of polypropylene fiber reduces fluidity and strength of SC,it causes 5% to 8% increase of high temperature residual compressive strength.Furthermore,spalling under high temperature does not occur in SC specimen containing fiber.

关 键 词：牺牲混凝土 聚丙烯纤维 自由水 孔隙率 强度 抗爆裂性能 

分 类 号：TU528[建筑科学—建筑技术科学]