道路混凝土在不同除冰盐盐冻环境下的耐久性研究

发布时间：2018-01-27 01:51

本文关键词： 除冰盐质量损失率相对动弹性模量最大抗冻融次数　出处：《内蒙古科技大学》2014年硕士论文　论文类型：学位论文

【摘要】：基础设施建设大力发展的今天，混凝土在公路、桥梁、机场、码头、建筑工程等方面得到广泛应用。为了保证冬季交通的正常运营，融雪剂(除冰盐)被大量使用，目前市场上的除冰盐种类较多，有NaCl、CaCl2、Ca(COOH)2、Mg(COOH)2、乙二醇等。不同除冰盐对道路混凝土的破坏程度不同，侵蚀机理不同，对生态环境的污染程度也不同，因此研究不同除冰盐环境下混凝土的抗冻耐久性具有重要意义。本文通过普通混凝土快速冻融试验方法，分析不同盐溶液(NaCl、CaCl2、CMA、Na2SO4)及其不同浓度(0%、3%、6%、12%、25%)对混凝土抗冻性的影响，得出盐冻环境下混凝土的质量损失、相对动弹性模量和混凝土立方体抗压强度的变化规律。在NaCl盐冻环境下，混凝土试件随着冻融次数的增加，试块表面剥浊程度逐渐加深，相对动弹性模量、立方体抗压强度逐渐下降。3%NaCl盐冻的试块破坏最为严重，冻融100次后质量损失达7.55%，相对动弹性模量为13.34%，混凝土立方体抗压强度下降了60%。在NaCl和CaCl2盐冻环境下混凝土耐久性相似，CaCl2盐冻对混凝土的侵蚀较小；其次，不同浓度的CMA在同一冻融次数下,混凝土的状态由好到差排列为：25%CMA＞12%CMA＞6%CMA＞3%CMA；再次，Na2SO4不易溶于水，盐冻仅50次，，相对动弹性模量下降到60%以下。盐冻100次后混凝土粗骨料暴露，质量损失急速增加，相对动弹性模量仅为20%。通过四种盐冻试验的对比，混凝土在3%浓度盐溶液中冻融损坏最为严重。溶液浓度越高，混凝土的耐久性越好。以3%浓度为例，混凝土的抗冻性依次为：CMA＞CaCl2＞NaCl＞Na2SO4(“＞”表示“优于”)。根据混凝土抗冻性的定量化分析，利用MATLAB数值分析软件拟合出不同浓度NaCl盐冻环境下混凝土最大抗冻融次数经验公式。为研究混凝土的盐冻提供一定的参考，对道路除冰盐的使用具有指导意义。
[Abstract]:Today, with the development of infrastructure construction, concrete is widely used in highway, bridge, airport, wharf, construction engineering and so on, in order to ensure the normal operation of winter traffic. Snow melting agent (deicing salt) is widely used. At present, there are many kinds of deicing salt in the market. Different deicing salts have different damage degree to road concrete, different erosion mechanism and different pollution degree to ecological environment. Therefore, it is of great significance to study the frost durability of concrete under different deicing salt environment. In this paper, through the rapid freeze-thaw test method of ordinary concrete, we analyze the different salt solution NaCl-CaCl2CMA-Na _ 2SO _ 4) and the different concentration of NaCl-CaCl _ 2-CMA-Na _ 2SO _ 4). The influence on the frost resistance of concrete is obtained, and the variation law of mass loss, relative dynamic elastic modulus and cube compressive strength of concrete under salt freezing environment is obtained. With the increase of freeze-thaw times, the surface peeling degree of concrete specimens is gradually deepened and the relative dynamic modulus of elasticity is increased under the environment of NaCl salt freezing. The compressive strength of the cube decreased gradually. 3% NaCl salt frozen the most serious damage, freeze-thaw 100 times after the mass loss of 7.55, the relative dynamic modulus of elasticity is 13.34%. The compressive strength of concrete cube is decreased by 60. The concrete durability is similar to that of CaCl _ 2 salt frozen concrete under NaCl and CaCl2 salt freezing environment, and the corrosion of concrete by CaCl _ 2 salt freezing is relatively small. Secondly, at the same freezing and thawing times, the state of the concrete is arranged from good to bad in the order of: 25CMA > 12CMA > 6CMA > 3CMA; Once again, Na _ 2SO _ 4 is not soluble in water, salt freezing is only 50 times, the relative dynamic modulus of elasticity is lower than 60%. After 100 times of salt freezing, the coarse aggregate of concrete is exposed, and the mass loss increases rapidly. The relative dynamic elastic modulus is only 20. Through the comparison of four kinds of salt freezing tests, the damage of concrete in 3% concentration salt solution is the most serious. The higher the solution concentration, the better the durability of concrete. Take 3% concentration as an example. The frost resistance of concrete is in the order of: CMA > CaCl2 > NaCl > Na _ 2SO _ 4 (">" means "superior"). According to the quantitative analysis of the frost resistance of concrete. The empirical formula of maximum freeze-thaw resistance of concrete under different concentrations of NaCl salt freezing environment is fitted by using MATLAB numerical analysis software, which provides a certain reference for the study of concrete salt freezing. It is of guiding significance for the use of deicing salt in road.
【学位授予单位】：内蒙古科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U414

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