海洋环境下混凝土的硫酸盐腐蚀机理

海水中存在的硫酸根离子传输至混凝土内部将导致其腐蚀破坏。针对矿粉掺量0～65%的C40引气混凝土进行海洋潮汐区、大气区和水下区腐蚀1～2a,测试其水溶和酸溶硫酸根离子浓度分布;分析水泥净浆中的腐蚀产物类型及含量。试验结果表明:海洋不同腐蚀区带混凝土中硫酸根离子传输量及传输深度排序为:潮汐区水下区大气区。混凝土中反应硫酸根离子与总硫酸根离子的关系服从线性函数分布,反应量占总硫酸根离子量的90%以上,反应的硫酸根离子量随腐蚀龄期增加而增加。海洋潮汐区和水下区生成的腐蚀产物量高于大气区,主要是钙矾石和石膏;海洋大气区暴露混凝土的腐蚀产物为钙矾石。对于P.I.52.5水泥制备的C40混凝土而言,掺加65%的矿粉有助于提升混凝土抗海洋硫酸根离子侵蚀能力。

Sulfate corrosion of concrete exposed to marine environment

Sulfate ions in seawater penetration into concrete would lead to damage of concrete in marine environment. In this paper, the air entraining concrete with 0-65% of GGBS content was exposed to marine tidal zone, atmosphere zone and submerged zone for 1~2 a. The water-soluble and acid-soluble sulfate ions profile were tested, and the corrosion products of cement paste in marine environment was analyzed. The experimental results shown that the order of the migration sulfate ion content and transmission depth of concrete exposed to different corrosion zones was in order of:tidal zone>submerged zone> atmosphere zone. The relationship between reactive sulfate ion and total sulfate ion in concrete could be expressed as a linear function. The reacted sulfate ion content accounted for more than 90% of total sulfate ions, and the amount reaction sulfate ion increased with the corrosion time. The amount of corrosion products including ettringite and gypsum were generated in pastes exposed to tidal zone and submerged zone. The corrosion product of concrete exposed to the atmosphere zone was only ettringite. For C40 concrete prepared with P.I.52.5 cement, cement replacement by 65% GGBS helps to improve the capacity of concrete to sulfate ion attack in marine environment.