应力及干湿循环作用下氯离子在混凝土中的渗透性研究

发布时间：2018-01-22 03:05

本文关键词： 氯离子渗透性应力干湿循环 SDWM模型耦合作用　出处：《中国建筑材料科学研究总院》2013年博士论文　论文类型：学位论文

【摘要】：目前世界范围内混凝土结构的耐久性问题日益凸显，受到各国科技人员和工业界的普遍重视。荷载和外界环境因素是影响混凝土结构耐久性的主要因素，研究应力及干湿循环条件下混凝土中氯离子的渗透性及其变化规律，并对处于该条件下混凝土结构的服役寿命进行预测，具有较高的实用价值。本文对这一课题进行了探索，研究内容和取得的成果如下：评价并改进了混凝土中氯离子渗透性应力加载装置，设计了应力条件下氯离子渗透性测试方法，实现了应力条件下混凝土中氯离子渗透性的快速测定。应力加载装置创新地采用碟簧加载的方式实现了对混凝土施加应力，借助应力传感器实现了装置的应力适时调控与恒载。氯离子渗透性测试方法首次将应力加载装置与NEL法和电通量法进行有效的结合（即CPS-NEL法和CPS-ASTM C1202法）。该方法具有操作快捷、评定准确和实用的特点，是一种用于评价氯离子在混凝土内渗透性的新型方法。系统分析了应力条件下氯离子在混凝土中的渗透行为。采用CPS-NEL法和CPS-ASTM C1202法，对氯离子在C30和C60混凝土中的渗透性进行了研究，分析了应力大小（应力比为0.1，0.3，0.5，0.7）和应力种类（拉应力和压应力）对渗透性的影响，得出了应力条件下混凝土中氯离子的渗透规律，获得了混凝土中氯离子渗透性变化的阈值应力比。研究了应力和干湿循环耦合作用下的混凝土中氯离子渗透性变化规律，创新地建立和论证了考虑应力和干湿循环因素的氯离子渗透模型。通过对混凝土中氯离子浓度的测试，分析了应力和干湿循环对混凝土渗透性的影响，，同时采用基于硝酸银显色法对应力和干湿循环耦合作用下的氯离子渗透规律进行了验证。在Fick第二定律的基础上建立了应力和干湿循环耦合作用下的氯离子渗透模型（SDWM模型），并对SDWM模型的计算值和混凝土内部氯离子浓度的实测值进行了验证，结果证实SDWM模型具有较高的可靠性。依据超声波、SEM和MIP等测试设备，分析了混凝土中内部损伤对氯离子渗透性能的影响。利用超声波法声学参数变化曲线对应力作用下混凝土内部的损伤进行了分析；利用SEM法观察了拉应力和干湿循环耦合作用下的混凝土内部微观形貌变化；采用MIP法对拉应力和干湿循环耦合作用下混凝土的孔隙率和孔径分布进行了测试，对其变化规律进行了分析。超声波、SEM和MIP法测试结果解释了应力和干湿循环耦合作用下混凝土渗透性的变化规律。基于在应力和干湿循环因素作用下建立的SDWM模型，对实体机构进行了寿命预测。采用“PERMIT”法对实体结构渗透性进行了测试，通过SDWM模型，计算出混凝土中与钢筋接触界面处在不同龄期时的氯离子浓度，根据钢筋腐蚀时的氯离子临界浓度值对实体结构的服役寿命进行了预测。
[Abstract]:At present, the durability of concrete structures in the world is becoming more and more prominent, which has been paid more and more attention by scientists and industry. Load and environmental factors are the main factors that affect the durability of concrete structures. The permeability and variation of chloride ions in concrete under the conditions of stress and dry-wet circulation are studied, and the service life of concrete structures under these conditions is predicted. This paper explores this subject, and the research contents and results are as follows: The chlorine ion permeability stress loading device in concrete is evaluated and improved, and the method of chloride ion permeability testing under stress condition is designed. The rapid measurement of chloride permeability in concrete under stress conditions is realized. The stress loading device innovatively applies the stress to concrete by the method of disc spring loading. The stress timely control and dead load are realized by means of stress sensor. The stress loading device is effectively combined with NEL method and electric flux method for the first time. That is, CPS-NEL method and CPS-ASTM C1202 method. Accurate and practical evaluation is a new method for evaluating the permeability of chloride ions in concrete. The permeation behavior of chloride ions in concrete under stress conditions was systematically analyzed. CPS-NEL method and CPS-ASTM C1202 method were used. The permeability of chloride ions in C30 and C60 concrete is studied, and the magnitude of stress (stress ratio is 0.1g / 0.3 / 0.5) is analyzed. The influence of the types of stress (tensile stress and compressive stress) on the permeability of concrete is obtained. The permeability law of chloride ions in concrete under stress conditions is obtained, and the threshold stress ratio of chloride ion permeability change in concrete is obtained. The variation of chloride ion permeability in concrete under the coupling of stress and dry-wet cycle is studied. The chloride permeation model considering stress and dry-wet cycle factors was established and proved. The influence of stress and wet cycle on the permeability of concrete was analyzed by testing the chloride ion concentration in concrete. At the same time, the chloride ion permeation law under the coupling of stress and dry-wet cycle was verified by silver nitrate coloration method. Based on the second law of Fick, the chlorine separation under the coupling of stress and dry-wet cycle was established. Subosmotic model (. SDWM model. The calculated values of SDWM model and the measured values of chloride concentration in concrete are verified. The results show that the SDWM model has high reliability. According to ultrasonic testing equipment, such as SEM and MIP. The influence of internal damage on chloride permeability in concrete is analyzed. The damage of concrete under stress is analyzed by ultrasonic acoustic parameter change curve. The microstructure of concrete under the coupling of tensile stress and wet and dry cycle was observed by SEM method. The porosity and pore size distribution of concrete under the coupling of tensile stress and dry-wet cycle were measured by MIP method. The results of SEM and MIP methods explain the variation of the permeability of concrete under the coupling of stress and dry-wet cycle. Based on the SDWM model established under the action of stress and dry-wet cycle, the life of solid mechanism was predicted. The permeability of solid structure was tested by "PERMIT" method. Through SDWM model, the concentration of chloride ion in concrete at different ages is calculated. The service life of solid structure is predicted according to the critical concentration of chloride ion in steel bar corrosion.
【学位授予单位】：中国建筑材料科学研究总院
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU528.0

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