硫酸盐镁盐复合侵蚀后混凝土的微观形貌特征

发布时间：2018-01-31 03:49

本文关键词： 硫酸盐镁盐混凝土微观形貌　出处：《农业工程学报》2015年09期 　论文类型：期刊论文

【摘要】：混凝土结构通常受土壤环境水中硫酸盐和镁盐溶液的侵蚀。为了探究硫酸盐和镁盐复合溶液侵蚀后纯水泥混凝土和掺矿粉微粉高性能混凝土的抗侵蚀性能,该研究设计了3个水胶比和2个矿粉掺量,经加水拌合、成型试件1050个,养护28 d后将其分别浸泡于硫酸盐和镁盐溶液中,侵蚀至规定龄期后测试其抗蚀系数、微观形貌。结果表明:水胶比为0.50时,混凝土界面中的孔隙多、孔径大,最大孔径为372.5μm,即使水胶比降低到0.35时,其孔结构的改善也不明显。当纯水泥混凝土试件在SO42-2 500 mg/L和Mg2+1 400 mg/L的硫酸盐镁盐中侵蚀4个月后,其孔隙中充满了Ca SO4·2H2O、3Ca O·Al2O3·3Ca SO4·32H2O(AFt)、Mg(OH)2和Mg O·Si O2·H2O等侵蚀产物,致使混凝土内部产生裂缝,边角处开始出现剥落,甚至变得酥松,表面浆体脱落严重,粗细集料分离等现象。当侵蚀时间超过2月时,其侵蚀系数随侵蚀龄期的延长呈降低的趋势,且均在0.85以下,说明32.5级普通硅酸盐水泥抗硫酸盐镁盐侵蚀的能力是有限的。矿渣微粉掺入后,混凝土界面的孔隙不仅极少,而且孔径也较小,最大孔径分别约为水胶比为0.50时的1/7和1/8,同时也减少了易被侵蚀的水化产物Ca(OH)2的含量,使混凝土界面结构密实程度增加,水胶比越低越明显。在高浓度的硫酸盐和镁盐(SO42-20 250 mg/L和Mg2+2 800 mg/L)的双重强侵蚀12个月后,试件边缘仍未发现侵蚀产物以及Mg SO4·7H2O、Na2SO4·10H2O和Mg2(OH)3Cl·4H2O等晶体,其抗蚀系数仍在0.85以上,未有降低的趋势,表明矿渣微粉的掺入能显著改善32.5级普通硅酸盐水泥所配制高性能混凝土的抗侵蚀性能。该研究可为混凝土在农业灌溉工程(坝基础、闸基础和渠道等)和大棚混凝土基础工程的使用提供数据支撑与理论基础。
[Abstract]:The concrete structure is usually eroded by sulfate and magnesium solution in soil environment water. In order to investigate the corrosion resistance of pure cement concrete and high performance concrete mixed with mineral powder after erosion by sulfate and magnesium salt composite solution. In this study, three water-binder ratios and two mineral powder contents were designed, and 1050 samples were formed by mixing with water. After 28 days of curing, the samples were immersed in sulfate and magnesium solution respectively. The corrosion resistance coefficient and microstructure of the concrete were measured after erosion to the specified age. The results showed that when the water-binder ratio was 0.50, the pore size in the interface of concrete was large and the maximum pore size was 372.5 渭 m. Even when the water-binder ratio is reduced to 0.35. The improvement of pore structure was not obvious. When pure cement concrete specimens were corroded in SO42-2 500 mg/L and Mg2 1 400 mg/L magnesium sulfate for 4 months. The pore is filled with Ca SO4 路2H 2O 3CA O 路Al2O3 路3Ca SO4 路32H 2O. Corrosion products such as Mg(OH)2 and MgO 路Sio _ 2 路H _ 2O lead to cracks in the concrete, the flaking of the edges and even the looseness of the surface slurry. When the erosion time exceeds February, the erosion coefficient decreases with the extension of erosion age, and the erosion coefficient is below 0. 85. The results show that the ability of 32.5 grade Portland cement to resist magnesium sulfate erosion is limited, and the pore size of concrete interface is not only small but also small after the addition of slag powder. The maximum pore size is about 1/7 and 1 / 8 when the water-binder ratio is 0.50, which also reduces the content of Ca(OH)2, which is easy to be corroded, and increases the compactness of concrete interface structure. The lower the water-binder ratio is, the more obvious it is, after 12 months of double strong erosion with high concentrations of sulfate and magnesium salt so _ 42-20 250 mg/L and Mg2 2 800 mg 路L ~ (-1). No erosion products and crystals such as mg SO4 路7H _ 2O Na _ 2SO _ 4 路10H _ 2O and Mg2(OH)3Cl 路4H _ 2O were found at the edge of the specimen. The corrosion resistance coefficient is still above 0.85, and there is no decreasing trend. The results show that the addition of slag powder can significantly improve the corrosion resistance of high performance concrete prepared by 32.5 grade ordinary Portland cement. This study can be used in the agricultural irrigation project (dam foundation). The use of concrete foundation and shed provides data support and theoretical basis.
【作者单位】：新疆农业大学水利与土木工程学院;新疆农业大学草业与环境科学学院;
【基金】：国家自然科学基金资助(50969010) 国家高等学校博士点专项科研基金资助(20106504110005) 新疆水利水电工程重点学科基金资助(XJzdxk-2010-02-12) 新疆维吾尔自治区研究生科研创新项目资助(XJGRI2014072)
【分类号】：TU528
【正文快照】： 吴福飞,侍克斌,董双快,等.硫酸盐镁盐复合侵蚀后混凝土的微观形貌特征[J].农业工程学报,2015,31(9):140-146.Wu Fufei,Shi Kebin,Dong Shuangkuai,et al.Microstructure characteristics of concrete after erosion of magnesium salts andsulfates[J].Transactions of the Ch

【参考文献】