氯盐环境混凝土中氯离子含量无损检测技术研究

发布时间：2018-03-10 07:30

  本文选题：氯盐环境　切入点：混凝土　出处：《中国矿业大学》2014年硕士论文　论文类型：学位论文

【摘要】：氯盐侵入是导致混凝土结构钢筋锈蚀的最重要因素之一，能够及时、准确掌握混凝土中氯离子分布状态，对于正确评价、预测混凝土耐久性和及时采取措施进行维修、维护可提供重要科学依据。本文以氯盐环境为背景，以多孔介质的传质传输基本理论为依据，采取试验研究和理论分析相结合的手段，对氯盐环境下混凝土中氯离子含量的无损检测技术及氯离子含量的在混凝土中分布发展进行了深入的研究。 采用恒电流阳极电解法制备氯离子无损检测探针，并对其极化的最佳条件进行研究。结果表明：最佳极化电流密度为0.4mA/cm2；最佳极化时间为5.5小时。 配制不同浓度和化学成份的氯盐溶液，系统地研究并检测了电解法制备的Ag/AgCl电极在盐溶液中的能斯特响应、电位响应时间特性、温度响应以及电位的重现性和长期稳定性。研究表明：无论是在NaCl溶液还是在NaCl+SPS溶液中探针电位与溶液的氯离子的浓度都能够保持较好的线性响应关系，并且拟合精度较高；电位响应时间较短，，为35s；温度系数较低，为0.418mV/℃；浸泡在加盐的混凝土模拟空隙液溶液中探针电位极差的最大值不超过2mV，平均值极差为2.9mV，探针保持了较好的长期稳定性。 研究了混凝土中氯离子含量的无损检测方法。通过测定在不同掺盐量混凝土试块由饱水到干燥过程中Ag/AgCl探针的电位和氯离子的含量，建立了混凝土中氯离子含量和电极电位间的相关性模型；研究了水灰比和混凝土的龄期对探针电位的影响，试验表明：在混凝土中氯离子浓度相同的情况下，水灰比越小，探针的电位越大，同种水灰比下，氯离子浓度越大，探针电位越小；混凝土水化前期会出现电位的极小值，然后逐渐回升，约28d后达到稳定值。 分别建立了模拟海洋和盐湖环境系统，应用埋入式无损检测探针定期测定了混凝土试件不同高度、不同深度处的氯离子含量大小，分析了氯盐环境下不同暴露条件氯离子在混凝土中的传输机理，并对氯离子的分布进行了预测。
[Abstract]:Chloride intrusion is one of the most important factors leading to the corrosion of reinforced bars in concrete structures. It can grasp the distribution of chloride ions in concrete timely and accurately. In order to correctly evaluate, predict the durability of concrete and take timely measures to carry out maintenance, Maintenance can provide an important scientific basis. Based on the background of chloride environment and the basic theory of mass transfer in porous media, this paper adopts the method of combining experimental research with theoretical analysis. The nondestructive detection technology of chloride ion content in concrete under chloride environment and the distribution and development of chloride ion content in concrete were studied in this paper. The chloride ion nondestructive detection probe was prepared by constant current anode electrolysis and the optimum conditions of its polarization were studied. The results show that the optimum polarization current density is 0.4 Ma / cm ~ 2 and the optimum polarization time is 5.5 hours. The characteristics of Nernst response and potential response time of Ag/AgCl electrode prepared by electrolytic method in salt solution were studied and tested systematically by preparing chloride solution with different concentration and chemical composition. The temperature response, the reproducibility and long-term stability of the potential. The results show that both the probe potential in NaCl solution and the concentration of chloride ion in NaCl SPS solution can maintain a good linear response relationship, and the fitting accuracy is high. The potential response time is shorter (35s), the temperature coefficient is low (0.418mV / 鈩

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