盐溶液环境中双掺混凝土内钢筋锈蚀速率的试验研究

发布时间：2018-05-22 20:48

本文选题：氯离子 + 硫酸根离子　；参考：《南京工业大学》2015年硕士论文

【摘要】：由于城市的快速发展,地铁轨道工程大量出现。由于地下轨道结构修筑于岩土介质中,其服役环境复杂,且轨道管片在形成初期常带有初始损伤,此外,轨道在服役期间会受到多重荷载作用,地质的不均匀沉降等多因素长期作用下,其初始损伤会不断劣化。地下环境中富含多种侵蚀性离子：氯离子、硫酸根离子等。初始损伤的存在为有害介质的扩散提供了便捷通道,使得钢筋混凝土结构进一步劣化,致使结构的耐久性较差而提早作废,很难达到预估的使用年限。目前,针对氯离子与硫酸根离子耦合作用下混凝土钢筋锈蚀规律的相关研究比较少。本文以氯离子浓度、硫酸根离子浓度、裂缝宽度以及保护层厚度为研究对象,在试验的基础上加以理论分析,研究以上几种因素对钢筋锈蚀速率的影响。本文的主要研究内容如下：(1)从钢筋锈蚀的重要性出发,总结了影响混凝土内部钢筋锈蚀的主要因素,理论分析了混凝土的锈蚀机理,并归纳了钢筋锈蚀主要的几种研究方法。(2)通过盐溶液浸泡加速试验,采用开路电位法、线性扫描伏安法以及塔菲尔极化曲线法,测得混凝土内钢筋的腐蚀电位、线性极化曲线、Tafel曲线等相关电化学参数。通过分析,试验结果表明：氯离子是影响钢筋锈蚀的主要因素,其浓度的越大,钢筋发生锈蚀的概率越大；硫酸根离子在侵蚀初期对钢筋锈蚀几乎没有影响,在侵蚀后期其存在对钢筋锈蚀有一定程度上的抑制作用；裂缝能够增加钢筋锈蚀概率,裂缝宽度越宽,发生锈蚀的概率越大；混凝土保护层厚度越薄,发生锈蚀概率越大。(3)根据线性极化曲线得到极化电阻,并从Tafel极化曲线中的斜率ba、be,以及B值,求得各种工况下的钢筋腐蚀电流密度,定量分析不同侵蚀条件下试块中锈蚀速率,以及各因素对钢筋锈蚀速率的影响。(4)从金属腐蚀电化学基本理论出发,回顾已有的混凝土内钢筋锈蚀速率模型的相关成果,并由各种工况下的钢筋腐蚀电流密度值,通过拟合确定复杂环境下腐蚀电流密度模型。
[Abstract]:Due to the rapid development of the city, subway track engineering appears in large numbers. Because the underground track structure is built in geotechnical medium, its service environment is complex, and the track segment often has initial damage in the initial stage of formation, in addition, the track will be subjected to multiple loads during the service period. The initial damage will continue to deteriorate under the long-term action of many factors, such as uneven settlement of geology. Underground environment is rich in a variety of corrosive ions: chloride ion, sulfate ion and so on. The existence of initial damage provides a convenient channel for the diffusion of harmful media, which makes the reinforced concrete structure worse, and the durability of the structure is poor, so it is difficult to achieve the estimated service life. At present, there are few researches on corrosion law of reinforced concrete under the coupling of chloride ion and sulfate ion. In this paper, chloride ion concentration, sulfate ion concentration, crack width and thickness of protective layer are taken as the object of study. Based on the experimental results, the effects of above factors on the corrosion rate of steel bar are studied. The main contents of this paper are as follows: (1) based on the importance of steel corrosion, the main factors affecting the corrosion of steel bars in concrete are summarized, and the corrosion mechanism of concrete is analyzed theoretically. The corrosion potential of steel bar in concrete was measured by open-circuit potential method, linear scanning voltammetry and Tafel polarization curve method. Linear polarization curve, Tafel curve and other related electrochemical parameters. The experimental results show that the chloride ion is the main factor affecting the corrosion of steel bars, and the higher the concentration of chloride ion is, the greater the probability of corrosion is, and the sulfate ion has little effect on the corrosion of steel bars at the beginning of corrosion. In the later stage of erosion, the corrosion of steel bar can be inhibited to some extent by the existence of crack, the probability of corrosion is increased by crack, the wider the crack width, the greater the probability of corrosion, the thinner the thickness of concrete cover, the greater the probability of corrosion. According to the linear polarization curve, the polarization resistance is obtained, and the corrosion current density of steel bar under various working conditions is obtained from the slope baobe and B value of the Tafel polarization curve, and the corrosion rate in the specimen under different erosion conditions is quantitatively analyzed. And the influence of various factors on the corrosion rate of steel bars. (4) based on the basic theory of metal corrosion electrochemistry, this paper reviews the relevant results of the existing corrosion rate models of steel bars in concrete, and according to the corrosion current density of steel bars under various working conditions, The corrosion current density model in complex environment was determined by fitting.
【学位授予单位】：南京工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU375

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