长期水热条件下活性粉末混凝土的微膨胀机理  被引量:4

Micro-expansion and Mechanism of Active Powder Concrete Under Long Term Hydrothermal Conditions

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作  者:侯剑桥 崔崇[1] 何兵 赵秦仪 马海龙[2] HOU Jianqiao;CUI Chong;HE Bing;ZHAO Qinyi;MA Hailong(School of Materials Science and Engineering,Nanjing University of Science and Technology,Nanjing 210094,China;National Preparatory School of Education,Ningxia University,Yinchuan 750002,China)

机构地区:[1]南京理工大学材料科学与工程学院,南京210094 [2]宁夏大学民族预科教育学院,银川750002

出  处:《硅酸盐学报》2018年第8期1149-1156,共8页Journal of The Chinese Ceramic Society

基  金:国家自然科学基金(51578289,51468053)资助

摘  要:将不同水灰比的活性混凝土(RPC)试样在200℃长期蒸压养护来模拟核废料放置环境,并测量养护过程中试样的质量、长度、动弹模量和微观形貌。结果表明:低水灰比RPC试样的质量随养护时间增加逐渐增加;动弹性模量在蒸压养护初期增加较快,蒸压养护96 h后呈现稳定状态;试样呈现先收缩后膨胀的变化规律。扫描电子显微镜观察微观形貌发现RPC基体致密无宏观缺陷,水热合成反应产生的托贝莫来石相随着养护逐步填充基体中少量的气孔和毛细孔。在低水灰比条件下,钢纤维对RPC膨胀的约束应力可以提升混凝土力学性能和耐久性。掺加钢纤维的活性粉末混凝土可作为核废料容器的优选材料。Reactive powder concrete(RPC) is widely used as nuclear waste containers due to its high strength and toughness. Durability is one of the key factors restricting the use of RPC in nuclear waste containers. In this study, the RPC samples with different water cement ratios were autoclaved in curing at 200℃ for a long time to simulate the storage environment of nuclear waste. The mass, length, dynamic elastic modules and microstructure of RPC samples with different water cement ratios were measured. The results show that for the samples with a low water cement ratio, the mass of the samples increases, the samples expand after a little shrinkage, the dynamic modulus of elasticity micro-expansion and its mechanism of reactive powder concrete under long-term hydrothermal conditions increase rapidly at the initial stage of autoclave curing, and then in a steady status after the hydration reaction of 96 h when the curing time increases. The images by scanning electron microscopy show that the matrix of RPC samples is compact without any microscopic defects. Besides, some pores and capillaries in the matrix are filled by tobermorite generated from hydrothermal synthesis. Under low water cement ratio conditions, the restrained stress of steel fibers on RPC expansion can improve the mechanical properties and durability of concrete, thus indicating that the RPC with steel fibers could be used as a preferred material for nuclear waste container.

关 键 词:活性粉末混凝土 核废料容器 托贝莫来石 膨胀 蒸压养护 

分 类 号:TU528[建筑科学—建筑技术科学]

 

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