装配整体式混凝土结构连接界面区氯离子传输特性

发布时间：2018-08-18 14:52

【摘要】：发展装配式建筑已成为建筑领域的国家战略,而装配整体式混凝土结构建筑仍是其中的主力军。然而,这种结构的耐久性问题却极少得到针对性关注。由于存在着物理不连续的连接界面区,由此引起了从侵蚀到腐蚀再到抗力退化等系列耐久性问题的特殊行为。因此,研究装配整体式混凝土结构连接界面区耐久性特性,对丰富混凝土结构耐久性理论、推动装配式混凝土结构技术应用与发展、提高建筑结构全寿命低碳化水平具有重要的学术与工程价值。本文以氯盐环境装配整体式混凝土结构耐久性问题为背景,抓住其新老混凝土连接界面区物理不连续这一关键前提,针对氯离子在连接界面区的传输行为这一基础问题,揭示装配整体式混凝土结构中预制和后浇混凝土连接界面区在不同界面粗糙度、不同压应力以及不同裂缝宽度条件下氯离子的侵蚀特性与机理,从而为界面区钢筋腐蚀研究、结构抗力退化、结构寿命预计等耐久性问题的研究奠定基础。通过三种不同界面粗糙度(平均灌砂深度1-2mm、6-7mm和11-13mm)和两个不同侵蚀时长(60d、180d)下氯离子干湿循环侵蚀试验研究,得到了界面区氯离子浓度随空间和时间的分布与演化的基本特征,结果表明,界面区比非界面区的氯离子浓度明显更高,据此,定义了氯离子浓度分布的界面区效应及其量化表达方法(界面区效应指数)。根据界面区效应指数分析,发现随着侵蚀深度的增加,界面区效应变大;随侵蚀时间的增长,界面区效应减小;界面粗糙度对界面区效应的影响呈现两头大中间小的特征,即界面粗糙度为1-2mm和11-13mm的界面区效应较为接近,且大于界面粗糙度为6-7mm的界面区效应。通过三种不同压应力(0、0.4fc、0.8fc)和两个不同侵蚀时长(60d、180d)下氯离子干湿循环侵蚀试验研究,并利用前述所定义的界面区效应指数进行分析,得到了压应力水平对界面区氯离子浓度分布与演化的影响规律,发现压应力的存在一方面减小了界面区效应,压应力越大,界面区效应越小,另一方面加剧了界面区氯离子的侵蚀程度。通过三种不同界面裂缝宽度(0、50mm、200mm)和两个不同侵蚀时长(60d、180d)下氯离子干湿循环侵蚀试验研究,并利用前述定义的界面区效应指数进行分析,得到了开裂程度对界面区氯离子浓度分布与演化的影响规律,发现界面处裂缝的存在提高了氯离子传输的界面区效应,且裂缝宽度越大,提高程度也越大。
[Abstract]:The development of prefabricated buildings has become a national strategy in the field of architecture, and the assembly of integral concrete structures is still the main force. However, the durability of this kind of structure is seldom concerned. Due to the existence of physically discontinuous interface regions, a series of durability problems such as corrosion, corrosion and resistance degradation are caused. Therefore, the durability characteristics of the interface zone of assembled integral concrete structures are studied, which can enrich the durability theory of concrete structures and promote the application and development of assembly concrete structure technology. It is of great academic and engineering value to improve the low carbonization level of the whole life of the building structure. In this paper, based on the durability problem of monolithic concrete structure assembled in chloride environment, the key premise of physical discontinuity in new and old concrete interface region is grasped, and the fundamental problem of chloride transport behavior in the connection interface region is discussed. The corrosion characteristics and mechanism of chloride ion in precast and post-cast concrete interface zone under different interface roughness, different compressive stress and different crack width are revealed in the assembly integral concrete structure, so as to study the corrosion of reinforcement in the interface zone. The study of durability problems such as structural resistance degradation and structural life prediction is the foundation. The basic characteristics of the distribution and evolution of chloride ion concentration with space and time in the interfacial zone were obtained by means of three different interface roughness (average sand filling depth 1-2mm 6-7mm and 11-13mm) and two different erosion periods (60d ~ 180d). The results show that the concentration of chloride in the interfacial region is significantly higher than that in the non-interfacial region. Accordingly, the interfacial effect of chloride concentration distribution and its quantitative expression method (interfacial effect index) are defined. According to the analysis of the interfacial zone effect index, it is found that with the increase of erosion depth, the interfacial zone effect increases, the interfacial zone effect decreases with the increase of erosion time, and the influence of interfacial roughness on the interfacial zone effect shows the characteristics of two ends between middle and small. That is, the interfacial zone effect of 1-2mm and 11-13mm is close, and larger than that of 6-7mm. Three different compressive stresses (0 0. 4 fc) and two different erosion periods (60 d ~ 180 d) were used to study the dry and wet cycling erosion of chloride ions, and the results were analyzed by using the interface zone effect index defined above. The influence of compressive stress level on the distribution and evolution of chloride ions in the interface region is obtained. It is found that the existence of compressive stress decreases the interfacial zone effect, and the greater the compressive stress is, the smaller the interfacial zone effect is. On the other hand, the erosion of chloride ions in the interface area is aggravated. The dry and wet cycling erosion tests of chlorine ions under three different interface crack widths (0 ~ 50 mm ~ 200 mm) and two different erosion periods (60 d ~ 180 d) were carried out, and the results were analyzed by using the interfacial zone effect index defined above. The influence of cracking degree on the distribution and evolution of chloride ions in the interface region is obtained. It is found that the existence of cracks at the interface increases the interfacial effect of chloride ion transport, and the wider the crack width, the greater the degree of improvement.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU37

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