盐冻环境下混凝土的微结构和氯离子渗透性

发布时间：2018-04-23 06:29

本文选题：冻融 + 盐冻　；参考：《建筑材料学报》2015年04期

【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50"m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.
[Abstract]:The effects of water / cement ratio and gas content on the deterioration of concrete under freeze-thaw and salt freezing conditions were studied. The microstructure of concrete and the transport of chloride ions in concrete under freezing and thawing conditions were analyzed. The variation of pore structure and chloride ion transport in concrete under salt freezing condition were analyzed. The results show that when the freeze-thaw cycle is 25 times, the mass loss rate of concrete under salt freezing condition is about 10 times that of concrete under water freezing condition, and at the early freeze-thaw stage, the mass loss rate of concrete under salt freezing condition is about 10 times that of concrete under water freezing condition. The loss of dynamic elastic modulus of concrete under salt freezing condition is slower than that of concrete under water freezing condition, and there are more bubbles in air-entrained concrete with pore diameter above 50 "m, and the average bubble spacing of unentrained concrete is 2.5 times of that of air-entrained concrete. Air entrainment can reduce the chloride ion permeability of concrete under freezing and thawing, but the enrichment phenomenon of chloride ion is found in the surface layer of air-entrained concrete after salt freezing. Considering the thickness range of the protective layer of reinforced concrete members, this may be unfavorable to the protection of steel bar.
【作者单位】：青岛理工大学蓝色经济区工程建设与安全山东省协同创新中心;青岛理工大学土木工程学院;青建集团股份公司;新冶高科技集团有限公司;
【基金】：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)
【分类号】：TU528

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