基于氯离子扩散系数的道路混凝土渗透性研究

发布时间：2018-03-13 10:43

本文选题：道路混凝土　切入点：氯离子扩散系数　出处：《兰州交通大学》2015年硕士论文　论文类型：学位论文

【摘要】：水泥混凝土路面因承载力强、水泥来源广而得以广泛应用,然而在当前自然环境因素和重载交通的作用下,水泥路面病害问题日益凸显,冻融、溶蚀、汽车尾气碳化和外界污染腐蚀等这些破坏都是借助水或氯离子等渗透性介质产生的,若能够有效地阻止外界的水分、气体及侵蚀性离子的侵入,就能够延长水泥路面的使用寿命,所以要提高道路混凝土的性能并预防病害的发生,归根结底是解决好道路混凝土的抗渗性问题。氯离子扩散系数描述了氯离子在混凝土中扩散的快慢,是表征混凝土渗透劣化破坏最本质的参数,也是评价混凝土渗透性的最经典指标。因此综合经济性和实用性,本文选择氯离子扩散系数作为道路混凝土抗渗性的评价指标,研究道路混凝土的抗渗性能。本文的主要成果是结合混凝土材料科学、统计学的相关知识,通过数值模拟建立混凝土随机骨料模型计算氯离子扩散系数,研究了微观孔隙及荷载对氯离子扩散系数的影响,建立了道路混凝土离子渗透性与孔隙结构关系模型,分析了离子渗透与水扩散的关系,全面系统地考察了道路混凝土抗渗性能评估方法。主要有以下几方面的内容:(1)根据粒径与骨料累计分布函数之间的关系,利用Matlab语言编制程序,建立了混凝土随机骨料有限元模型用于计算道路混凝土的氯离子扩散系数,讨论了界面对混凝土渗透性的影响;(2)以统计学原理为基础,引入分形理论研究了孔隙结构、孔隙量参数与道路混凝土氯离子扩散系数之间的关系,并对孔隙参数和氯离子扩散系数进行多元回归分析,建立了氯离子扩散系数与孔隙结构关系模型以评价道路混凝土的渗透性;(3)通过研究轴压和弯曲荷载下的氯离子扩散系数建立了不同荷载作用下的氯离子扩散系数规律曲线,对比了荷载作用下和未加载时的氯离子扩散系数的变化,以更实际地反映道路混凝土中的氯离子渗透情况;(4)建立了多雨地区道路混凝土中滞留水扩散模型,对比了氯离子渗透与水扩散之间的关系以更准确地反映混凝土的渗透性,并通过上述分析提出了提高道路混凝土抗渗性能的一些措施。本文采用多角度全面系统地分析研究了道路混凝土抗渗性能,具有理论明确、系统完整、实用性等特点,对水泥混凝土路面的抗渗性评价具有参考价值。
[Abstract]:Cement concrete pavement is widely used because of its strong bearing capacity and wide cement source. However, due to the effect of natural environment and heavy traffic, the problem of cement pavement disease is becoming more and more serious, freeze-thaw, corrosion, etc. Automobile exhaust carbonization and environmental pollution and corrosion are all caused by the use of permeable media such as water or chlorine ions. If the external water, gas and corrosive ions can be effectively prevented from invading, It can prolong the service life of cement pavement, so it is necessary to improve the performance of road concrete and prevent the occurrence of disease. In the final analysis, the problem of impermeability of road concrete is solved well. The chloride diffusion coefficient describes the speed of chloride diffusion in concrete, and is the most essential parameter to characterize the percolation deterioration of concrete. It is also the most classical index to evaluate the permeability of concrete. Therefore, comprehensive economy and practicability, this paper chooses chloride ion diffusion coefficient as the evaluation index of road concrete impermeability. The main achievement of this paper is to establish a random aggregate model of concrete by numerical simulation to calculate the chloride diffusion coefficient, which is based on the knowledge of concrete material science and statistics. The influence of micro-pore and load on chloride ion diffusion coefficient is studied. The relationship model between ionic permeability and pore structure of road concrete is established, and the relationship between ion permeation and water diffusion is analyzed. The evaluation method of anti-seepage performance of road concrete is systematically and comprehensively investigated. The main contents are as follows: 1) according to the relationship between particle size and aggregate cumulative distribution function, the program is compiled by Matlab language. The finite element model of concrete random aggregate is established to calculate the chloride diffusion coefficient of road concrete. The influence of interface on the permeability of concrete is discussed. Based on the statistical principle, the pore structure is studied by introducing fractal theory. The relationship between porosity parameter and chloride ion diffusion coefficient of road concrete was studied. The pore parameters and chloride ion diffusion coefficient were analyzed by multivariate regression analysis. The relationship model between chloride ion diffusion coefficient and pore structure is established to evaluate the permeability of road concrete. By studying the chloride ion diffusion coefficient under axial compression and bending load, the regularity curve of chloride ion diffusion coefficient under different loads is established. The variation of chloride diffusion coefficient under load and under no load is compared to reflect the chloride ion permeation in road concrete more practically. The model of residual water diffusion in road concrete in rainy area is established. The relationship between chloride ion permeation and water diffusion is compared to reflect the permeability of concrete more accurately. Through the above analysis, some measures to improve the impermeability of road concrete are put forward. In this paper, the impermeability of road concrete is analyzed and studied in a comprehensive and systematic way from many angles, which has the characteristics of clear theory, complete system, practicability and so on. It has reference value for evaluating the impermeability of cement concrete pavement.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U414

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