盐溶液浓度差对混凝土单面抗冻性的影响
王发洲 , 张梓鑫 , 李 明 , 黄大凡 , 朱 瑶宏
(1.武汉理工大学硅酸盐建筑材料国家重点实验室,湖北武汉430070;
2.宁波市轨道交通工程建设指挥部,浙江宁波31500O)
摘要:通过改变混凝土内、外部盐溶液浓度,研究了盐溶液浓度差对混凝土单面盐冻剥落的影响.
结果表明:在预吸水过程中,氯离子扩散规律符合Fick第二定律,在中、低盐溶液浓度或存在内外
浓度差的情况下,冻融过程对混凝土表面附近氯离子浓度分布影响显著;混凝土内、外部盐溶液浓
度差对混凝土盐冻剥落影响显著;当混凝土内部的盐溶液浓度低于外部时,盐冻剥落量最大,且远
大于3 (质量分数)盐溶液中冻融的混凝土.
关键词:浓度差;混凝土;单面盐冻;盐溶液
中图分类号:TU528.01 文献标志码:A doi:10.3969/j.issn.1007—9629.2O14.01.025
Influence of Chloride Solution COncentrati0n Difference on
Salt Frost Scaling of Concrete
WANG Fazhou , ZHANG Zixin , LI Ming , HUANG Dafan , ZHU Yaohong
(1.State Key Laboratory of Silicate M aterials for Architectures,W uhan University of Technology,W uhan
430070,China;2.Ningbo Rail Transit Headquarters of Construction,Ningbo 315000,China)
Abstract:Influence of chloride solution concentration difference on scaling of concrete by the deicer salt
was studied by changing the internal and external chloride solution concentration of concrete.The test re—
sults indicate that the chloride ion diffusion process matches the Fick’S second law during the pre—saturated
period of samples in chloride solution.The chloride ion concentration distribution on the concrete surface is
obviously affected by the freezing and thawing process when chloride ion concentration is low (3 ,by
mass)or internal and external concentration difference exists. The internal and externa1 concentration
difference significantly affects the salt frost scaling of concrete.W hen the internal concentration is lower
than the external concentration,the concrete scaling reaches a maximum value,which is much greater than
that of specimens tested with the chloride solution concentration of 3 ,which is generally regarded as the
highest concentration for concrete deterioration.
Key words:concentration difference;concrete;salt frost scaling;chloride solution
路用混凝土面临着除冰盐和冻融的综合劣化作
用,其破坏形式为表面逐层剥落.研究口 表明,混凝
土盐冻破坏存在一个最大的破坏浓度,一般认为在
3 9/5(质量分数)左右.有些学者_4 认为,这是由于氯
化钠既降低了盐溶液的结冰点,同时又提高了盐溶
液的饱水度所致.杨全兵l5 ]通过试验证明了这一
点.在过去,对混凝土路面冻融破坏的研究多采用在
3 氯化钠溶液中吸水、冻融的方法,这与混凝土路
面的实际使用状况存在一定差异.对于单面盐冻破
坏机理,国内外学者仍难以达成共识_7].Marchand
等l3 研究了不同溶液浓度对混凝土盐冻剥落的影
响,发现混凝土外部溶液浓度对其盐冻剥落影响更
大.Litvan_l8 研究发现,混凝土外部的盐溶液可导致
其内部水分向表面迁移,这些水结冰时起冰塞作用,
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