混凝土在硫酸盐冻融中的损伤与离子传输

发布时间：2018-04-28 21:40

本文选题：混凝土 + 冻融循环　；参考：《建筑材料学报》2015年03期

【摘要】：将C30和C50系列引气混凝土在质量分数5%Na2SO4或5%Na2SO4+3.5%NaCl溶液中自然浸泡或快速冻融循环,测试盐冻过程中混凝土表面和内部的超声声时、混凝土中水溶及酸溶SO2-4质量分数、孔结构演变和热谱.结果表明:超声声时能较好反映混凝土在盐冻过程中的损伤演化,其表面和内部超声声时均先轻微上升,然后保持稳定,当混凝土损伤严重时迅速上升.冻融过程中的低温环境可降低混凝土中SO2-4扩散速度和反应SO2-4量,但冻融损伤程度的增加将导致混凝土中SO2-4扩散速度增加.混凝土在复合盐溶液中冻融循环时,其SO2-4反应能力是Na2SO4溶液中盐冻混凝土的2倍,生成的钙矾石、硅灰石膏和石膏腐蚀产物更多,毛细孔增加2.2倍,最可几孔径提高了8nm,混凝土表面剥落更为严重.
[Abstract]:C30 and C50 series air-entrained concrete were naturally immersed in mass fraction 5%Na2SO4 or 5%Na2SO4 3.5%NaCl solution or frozen and thawed quickly. The mass fraction of water-soluble and acid-soluble SO2-4 in concrete was measured when supersonic sound on the surface and inside of concrete was measured in the process of salt freezing. Evolution of pore structure and thermal spectrum. The results show that supersonic sound can better reflect the damage evolution of concrete in the process of salt freezing. The surface and internal ultrasonic sound of concrete rise slightly and then remain stable, and then rise rapidly when the concrete damage is serious. The low temperature environment during freeze-thaw process can reduce the diffusion rate of SO2-4 and the amount of reactive SO2-4 in concrete, but the increase of damage degree of freeze-thaw will lead to the increase of diffusion velocity of SO2-4 in concrete. When the concrete is frozen and thawed in the composite salt solution, its SO2-4 reaction ability is twice as much as that of the salt frozen concrete in the Na2SO4 solution, and the ettringite, wollastonite paste and gypsum corrosion products are more produced, and the capillary pores increase by 2.2 times. The maximum pore size is increased by 8 nm, and the concrete surface spalling is more serious.
【作者单位】：青岛理工大学土木工程学院;东南大学江苏省土木工程材料重点实验室;
【基金】：国家自然科学基金资助项目(51378269,51178230) 青岛市科技计划项目(13-1-4-176-jch,13-1-4-115-jch) 山东省高校优秀创新团队基金资助项目(2012-7-9)
【分类号】：TU528

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