【作者】 马昆林；

【导师】 谢友均；

【作者基本信息】 中南大学 ， 道路与铁道工程， 2009， 博士

【摘要】 盐溶液对混凝土材料的侵蚀是导致混凝土结构劣化的重要原因。本文针对混凝土盐结晶侵蚀问题,运用混凝土材料科学、物理化学、热力学以及结晶学等基本原理,通过宏观试验和微观测试分析,较系统地研究了盐溶液在混凝土中的传输和结晶过程,探讨了主要侵蚀性盐对混凝土结晶侵蚀的破坏机理,提出了混凝土抗盐物理结晶侵蚀性能的试验评价方法。取得的主要研究成果如下:1、结合对典型工程的实地调查以及室内试验研究,分析了盐溶液在不同环境条件下对混凝土结构侵蚀劣化的过程。针对混凝土结构物遭受盐结晶物理侵蚀破坏的特征,归纳了三种容易受盐结晶物理侵蚀的工程类型,即毛细上升结晶型侵蚀、临空而结晶型侵蚀和干湿循环结晶型侵蚀。2、基于室内试验模拟研究,得出了盐结晶侵蚀下混凝土力学性能的退化规律及其微观结构的变化特征,揭示了盐溶液物理结晶侵蚀造成混凝土孔结构粗化的机理。3、系统分析了盐溶液通过毛细虹吸作用和扩散作用在混凝土中的传输过程,提出了基于毛细作用下盐溶液在混凝土中的传输模型,建立了盐溶液侵入混凝土的传输动力学公式。4、深入研究了盐溶液在混凝土孔隙中的结晶过程,提出了混凝土中孔溶液的蒸发速率和盐溶液对混凝土的侵入速率是混凝土中盐溶液结晶及其晶体生长的控制因素,建立了环境作用下混凝土盐结晶的动力学方程。5、比较了硫酸钠和氯化钠两种主要盐类对混凝土物理结晶侵蚀破坏的特点。揭示了相对湿度变化下,硫酸钠两种主要结晶产物之间的晶型转变是造成混凝土盐结晶物理侵蚀的主要原因。氯化钠对混凝土物理结晶侵蚀作用不明显,主要是由于常温下氯化钠溶液较难达到过饱和。6、基于混凝土盐结晶物理侵蚀破坏机理的研究成果,研发了一种测试混凝土抗结晶物理侵蚀破坏性能的新方法,提出了相应的评价参数和指标,试验验证了该方法的可行性与有效性。更多还原

【Abstract】 Salt solution attack on concrete is one of the main reasons for concrete deterioration, which has been focused along by researchers over the world. Based on the theoretical analysis by physical chemistry, thermodynamics and crystallization science and the macro/microscope testing the physical crystallization attack of ambient salt solution on concrete was studied systematically in present paper, involving the investigation of transportation process and crystallization process of salt solution in concrete as well as the corresponding mechanisms of salt crystallization attack on concrete. Furthermore, a new experimental method was developed to evaluate the resistance of concrete to crystallization attack.The main achievements and contribution obtained in the thesis are as follows:1. According to the investigation of representative environment in practice and experimental results, the deterioration characteristics of concrete served in different salt solution environment conditions were summarized. It was founded that the capillary siphon effect, windward-side effect and dry-wet-circle effect were the three main reasons resulted in crystallization attack of concrete under salt solution.2. Based on the laboratory simulation experiment by dry-wet cycles and partial-immersion method, evolution of mechanical properties and the microstructure of concrete were obtained, and the corresponding mechanism was expounded.3. Transportation process of salt solution in concrete driven by capillary siphon effect and diffusion effect was analyzed. And thus the transportation model of salt solution based upon capillary effect in concrete was proposed, as well as the transportation kinetics equation of salt solution was established.4. On the basis of analysis of salt solution crystallization process in concrete pore, it is founded that the crystal growth of in concrete pore was influenced greatly by two factors such as the evaporation rate of solution in concrete pores and ingress velocity of salt solution into concrete. And thus the crystallization kinetics equation of salt solution in concrete was established.5. Deterioration characteristics caused by physical crystallization attacks of sodium sulfate and sodium chloride on concrete, respectively, were compared. The crystal conversion of two crystals of mirabilite and thenardite of sodium sulfate is the main reason resulted in the physical crystallization attack on concrete under relative humidity change condition. The physical crystallization attack of sodium chloride on concrete is relative weak, which may be the reasons that it is hard to reach super-saturation for sodium chloride solution in room temperature.6. Based on the above theoretical analysis and experimental investigations, a new experimental method was developed to assess the resistance of concrete to crystallization attack, and the corresponding evaluating parameters were also put forward. In addition, some experiments were carried out to examine the feasibility and validity of the method.更多还原