抗氯盐高性能混凝土抗氯离子渗透性能时变规律实验研究
发布时间：2019-01-07 19:41
【摘要】：抗氯盐高性能混凝土是采用低水胶比和优质矿物掺合料等技术措施配制的高性能混凝土，由于它具有优良的抗氯离子渗透性能，采用这种技术现已成为解决氯盐环境中混凝土结构耐久性问题的主要措施。随着沿海经济的腾飞，抗氯盐高性能混凝土具有广阔的发展前景和应用价值，但调研发现抗氯盐高性能混凝土的研究还存在一些亟待解决的问题，例如抗氯盐高性能混凝土热物理性能研究很少，缺乏可利用的实测数据，由此是否导致混凝土开裂风险增加的问题还不明确；我国不同规范所用混凝土抗氯离子渗透性能的评定体系存在差异，造成不同规范评估混凝土抗氯离子渗透性能可能得出不同结论；混凝土结构寿命预测研究中氯离子扩散模型所用的龄期系数取值存在较大差异，缺少与我国混凝土原材料相适应的龄期系数取值方法等。 针对这些问题，本文进行了大量的试验研究工作，实测了抗氯盐高性能混凝土热物理性能基本参数，采用电量综合法研究了混凝土一年内龄期抗氯离子渗透性能，并通过五年龄期自然扩散法和电量综合法试验对比研究了混凝土抗氯离子渗透性能的时变规律。在本文研究情况下，可得出主要结论如下： （1）掺入大量矿物掺合料可有效降低混凝土的绝热温升值，矿物掺合料掺量、种类及比例对混凝土导热、导温系数和比热容影响较小。抗氯盐高性能混凝土导热、导温和比热性能可采用普通混凝土计算方法计算。 （2）电加速试验采用56天龄期混凝土氯离子扩散系数评价混凝土抗氯离子渗透性能结果较为合适，由于电量值和氯离子扩散系数有一定相关性，可用本文划分的混凝土电量值和氯离子扩散系数双指标体系评判混凝土抗氯离子渗透性能等级。 （3）混凝土抗氯离子渗透性能随龄期的延长而显著提高，氯离子扩散系数符合指数衰减规律，其龄期系数与混凝土水胶比和矿物掺合料掺量等因素有关，可用本文所得公式计算水下环境混凝土龄期系数。延长养护龄期可有效降低混凝土初始氯离子扩散系数，，但对混凝土氯离子扩散时变规律几乎没有影响。 （4）基于电加速方法前两年龄期试验结果得到混凝土氯离子扩散系数时变规律与自然扩散法试验结果基本保持一致，可真实有效的反映混凝土抗氯离子渗透性能时变规律。为增加寿命预测的准确度，混凝土结构使用寿命预测建议采用一年龄期或更长龄期工程实测氯离子扩散系数作为预测起点。
[Abstract]:Chlorine salt resistant high performance concrete is a kind of high performance concrete prepared by low water / binder ratio and high quality mineral admixture. This technique has become the main measure to solve the durability problem of concrete structure in chloride environment. With the rapid development of coastal economy, anti-chlorine-resistant high performance concrete has broad development prospects and application value, but the investigation and research found that there are still some problems to be solved urgently in the research of chloride resistant high performance concrete. For example, there are few researches on the thermophysical properties of chloride resistant high performance concrete, and it is not clear whether it will lead to the increase of cracking risk of concrete. There are differences in the evaluation system of chloride ion permeability of concrete used in different codes in China, which may lead to different conclusions in evaluating the chloride ion permeability of concrete under different specifications. In the study of life prediction of concrete structures, there are great differences in the age coefficients used in the chloride diffusion model, and there is a lack of the age coefficient method suitable for the raw materials of concrete in our country, and so on. In order to solve these problems, a great deal of experimental work has been carried out in this paper, and the basic parameters of the thermophysical properties of high performance concrete resistant to chloride salt have been measured, and the resistance to chloride ion permeability of concrete in one year has been studied by the method of electricity quantity synthesis. The time-varying law of chloride permeation resistance of concrete was studied by comparing the natural diffusion method of five years and the electric quantity synthesis method. In this paper, the main conclusions can be drawn as follows: (1) adding a large amount of mineral admixtures can effectively reduce the adiabatic temperature appreciation of concrete. The influence of temperature conductivity and specific heat capacity is small. The thermal conductivity and specific heat transfer of chloride resistant high performance concrete can be calculated by ordinary concrete calculation method. (2) in the electric accelerated test, the chloride ion diffusion coefficient of 56 days old concrete is suitable to evaluate the chloride ion permeability of concrete, because of the correlation between the electricity quantity and the chloride ion diffusion coefficient. The grade of chloride permeation resistance of concrete can be evaluated by the two-index system of concrete electric quantity and chloride ion diffusion coefficient which is divided in this paper. (3) the permeability of concrete to chloride ion increases with the increase of age, and the diffusion coefficient of chloride ion accords with the law of exponential attenuation, and its age coefficient is related to the factors such as the ratio of concrete to binder and the amount of mineral admixture, etc. The age coefficient of underwater environment concrete can be calculated by the formula obtained in this paper. Prolonging the curing age can effectively reduce the initial chloride diffusion coefficient of concrete, but have little effect on the time-varying rule of chloride ion diffusion in concrete. (4) based on the experimental results of the first two years of the electric acceleration method, the time-varying law of chloride diffusion coefficient of concrete is basically consistent with that of the natural diffusion method, which can reflect the time-varying law of chloride ion permeation resistance of concrete. In order to increase the accuracy of life prediction, it is suggested that the measured chloride diffusion coefficient of concrete structures should be used as the starting point for the prediction of the service life of concrete structures.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU528
[Abstract]:Chlorine salt resistant high performance concrete is a kind of high performance concrete prepared by low water / binder ratio and high quality mineral admixture. This technique has become the main measure to solve the durability problem of concrete structure in chloride environment. With the rapid development of coastal economy, anti-chlorine-resistant high performance concrete has broad development prospects and application value, but the investigation and research found that there are still some problems to be solved urgently in the research of chloride resistant high performance concrete. For example, there are few researches on the thermophysical properties of chloride resistant high performance concrete, and it is not clear whether it will lead to the increase of cracking risk of concrete. There are differences in the evaluation system of chloride ion permeability of concrete used in different codes in China, which may lead to different conclusions in evaluating the chloride ion permeability of concrete under different specifications. In the study of life prediction of concrete structures, there are great differences in the age coefficients used in the chloride diffusion model, and there is a lack of the age coefficient method suitable for the raw materials of concrete in our country, and so on. In order to solve these problems, a great deal of experimental work has been carried out in this paper, and the basic parameters of the thermophysical properties of high performance concrete resistant to chloride salt have been measured, and the resistance to chloride ion permeability of concrete in one year has been studied by the method of electricity quantity synthesis. The time-varying law of chloride permeation resistance of concrete was studied by comparing the natural diffusion method of five years and the electric quantity synthesis method. In this paper, the main conclusions can be drawn as follows: (1) adding a large amount of mineral admixtures can effectively reduce the adiabatic temperature appreciation of concrete. The influence of temperature conductivity and specific heat capacity is small. The thermal conductivity and specific heat transfer of chloride resistant high performance concrete can be calculated by ordinary concrete calculation method. (2) in the electric accelerated test, the chloride ion diffusion coefficient of 56 days old concrete is suitable to evaluate the chloride ion permeability of concrete, because of the correlation between the electricity quantity and the chloride ion diffusion coefficient. The grade of chloride permeation resistance of concrete can be evaluated by the two-index system of concrete electric quantity and chloride ion diffusion coefficient which is divided in this paper. (3) the permeability of concrete to chloride ion increases with the increase of age, and the diffusion coefficient of chloride ion accords with the law of exponential attenuation, and its age coefficient is related to the factors such as the ratio of concrete to binder and the amount of mineral admixture, etc. The age coefficient of underwater environment concrete can be calculated by the formula obtained in this paper. Prolonging the curing age can effectively reduce the initial chloride diffusion coefficient of concrete, but have little effect on the time-varying rule of chloride ion diffusion in concrete. (4) based on the experimental results of the first two years of the electric acceleration method, the time-varying law of chloride diffusion coefficient of concrete is basically consistent with that of the natural diffusion method, which can reflect the time-varying law of chloride ion permeation resistance of concrete. In order to increase the accuracy of life prediction, it is suggested that the measured chloride diffusion coefficient of concrete structures should be used as the starting point for the prediction of the service life of concrete structures.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU528
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