| 摘要: |
| 研究了水灰比、含气量等因素对混凝土在冻融和盐冻环境下劣化的影响，进行了混凝土微观形貌分析和冻融条件下氯离子在混凝土中的传输性试验，分析了盐冻条件下混凝土孔结构变化及氯离子传输规律.结果表明：当冻融循环25次时，盐冻条件下混凝土的质量损失率约是水冻条件下混凝土质量损失率的10倍；在冻融早期，盐冻条件下的混凝土动弹性模量损失比水冻条件下的混凝土动弹性模量损失缓慢；引气混凝土中50μm以上孔径的气泡较多，未引气混凝土的平均气泡间距为引气混凝土的2.5倍；引气能够降低冻融下混凝土的氯离子渗透性，但盐冻后引气混凝土表层有氯离子富集现象，考虑到钢筋混凝土构件的保护层厚度范围，这有可能不利于钢筋的保护. |
| 关键词: 冻融 盐冻 微结构 孔溶液 氯离子渗透性 |
| DOI：103969/jissn1007 9629201504017 |
| 分类号: |
| 基金项目:国家重点基础研究发展计划（973 计划）项目（2015CB655100）；国家自然科学基金重点国际合作项目（51420105015）；山东省高等学校科技计划项目（J14LG05）；青岛市基础研究联合基金计划（13 1 4 115 jch） |
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| Microstructures and Chloride Permeability of Concretes under Salt Frost |
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WAN Xiaomei1, ZHANG Tongbo2, ZHAO Tiejun1, JIANG Chongbo2, REN Xuchen3
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1.Cooperative Innovation Center of Engineering Construction and Safety in Shandong Blue Economic Zone, Qingdao Technological University, Qingdao 266033, China;2.Qingjian Group Co., Ltd., Qingdao 266071, China;3.New Matallurgy Hitech Group Co., Ltd., Beijing 100081, China
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| Abstract: |
| Performance degradation of concretes with varied water cement ratio and air content under freeze thaw cycles or salt frost cycles were investigated. After suffering from salt frost, microstructures of hardened cement pastes were analyzed by mercury intrusion method and scanning electron microscope, and chloride transport performance was measured experimentally. The results show that, mass loss of concrete after 25 times of salt frost cycles is 10 times of that after pure water frost. At early stage of freeze thaw cycles, there is a small descent of dynamic elastic modulus of concrete after salt frost compared with the one after water frost. There is a large amount of air voids with size of more than 50μm in air entrained concrete. Mean space of air void in non air entrained concrete is 2.5 times of that in air entrained concrete. Chloride penetration of concrete is weakened by increasing air content. However, chloride ions concentrate in surface layer of concrete, which may be unfavorable for reinforcement protect against corrosion considering the depth of cover to reinforcement. |
| Key words: freeze thaw salt frost microstructure pore solution chloride penetration |
