【作者】 刘军；

【导师】 谢友均； 邢锋；

【作者基本信息】 中南大学 ， 土木工程， 2013， 博士

【摘要】 渗透性能对于混凝土的寿命预测、耐久性设计与施工具有重要的意义,但对于内含氯离子混凝土试件,RCM的试验方法不再适用。为克服试验过程中试件内含氯离子对测试结果的影响,客观评价已受氯盐作用混凝土的耐久性能,本文采用碘离子代替氯离子作为试验的渗透离子,运用混凝土材料学、物理化学等基本原理,通过宏观试验和微观测试分析,重点研究了碘离子在混凝土中的迁移过程和结合机理,并与氯离子在混凝土中的传输过程进行对比分析,在此基础上提出基于碘离子传输特征的混凝土渗透性快速评价试验方法(Rapid Iodine Migration, RIM)。取得的主要研究成果如下：(1)系统分析了碘离子和氯离子作用对混凝土微观孔结构、表层渗水性能及水化浆体的影响,发现碘离子和氯离子对混凝土材料的作用有相似的效果,而且混凝土工程的服役环境及自身的材料组成都不含碘离子的特征,确定了碘离子代替氯离子作为试验渗透离子的有效性。(2)提出了淀粉-碘酸钾显色法的试验方法,用于测试自由碘离子在混凝土中的渗透深度。(3)研究了淀粉-碘酸钾显色法对测量碘离子渗透深度的有效性,以及水灰比和粉煤灰掺量对显色边界浓度的影响,对比分析了碘离子和氯离子显色边界浓度的相关性规律。(4)引入浸泡溶蚀系数和离子渗透系数2个参数,建立了综合考虑离子结合能力、扩散系数的时间依赖性、服役环境和离子特性的混凝土离子扩散新方程,解决了不同离子在混凝土中扩散的问题,根据碘离子和氯离子实际扩散过程的试验结果验证了新方程的有效性。(5)对比研究了自然浸泡下,碘离子和氯离子在混凝土中的沉积量和渗透深度的变化规律,渗透深度相同时,碘离子的累计沉积量大于氯离子,水灰比越大,沉积量的差值也越大,随着渗透深度的增加,碘离子和氯离子的累计沉积量逐步接近；发现渗透深度与水灰比的关系密切,可以使用含有水灰比的幂函数来反映渗透深度的变化规律。(6)基于碘离子在混凝土中的传输特性和RCM的试验原理,建立了采用碘离子评价混凝土渗透性的快速试验方法(RIM)；引入显色深度修正系数,能将RIM试验结果转换为RCM结果；试验证明,RIM的试验方法可以测量内含氯离子混凝土试件的离子快速渗透系数。更多还原

【Abstract】 Chloride permeability has great significance for service life prediction, durability design and construction of concrete structure. However, the conventional RCM (Rapid Chloride Migration) method for chloride permeability assessment is no longer applicable for concrete structure which has contained chloride ions. To overcome the influence of the interior chloride ions on the test result and realistically assess the service life of chloride-carrying concrete structure, this thesis proposes to use iodide ions as migrating ions, instead of chloride ions, in migration tests for permeability evaluation. In light of concrete material science, physico-chemistry and other basic principles, based on comprehensive macroscopic tests and microscopic analyses, the transport process and binding mechanisms of iodide ions in concrete are investigated and compared with that of chloride ions. Based on this study, a new concrete permeability evaluation method is developed, i.e. RIM (Rapid Iodide Migration) test.Main results of the present study are drawn as follow:(1)The influences of iodide ions and chloride ions on the pore structure, surface-layer sorptivity and paste micro structure are systematically studied, and it is found that the effects of these two kinds of ions are similar. Since there is no iodide ions neither in surrounding environment nor inside the concrete, iodine ions can be used as migrating ions instead of chloride ions in migration tests for permeability assessment.(2)Starch-potassium iodate colorimetric method is proposed to test the penetration depth of free iodide ions in concrete.(3)The effectiveness of the starch-potassium iodate colorimetric method for the determination of iodide penetration depth, and the influences of w/c and fly ash amount on the colorimetric boundary concentration of iodide ions are deeply examined. The correlation between the iodide colorimetric boundary concentration and the chloride colorimetric boundary concentration based on AgNO3colorimetric method is discussed.(4)In consideration of the binding capacity, time-dependency of diffusion coefficient, service environment and ion characteristics, an immersion leaching factor and the diffusion coefficient are used to build a new equation describing the diffusion process of ions in concrete. This new equation can be used to describe the diffusion of different ions, and has been validated by experimental results of the diffusion of iodide ions and chloride ions.(5)This research comparatively studies the evolutions of the deposition amount and penetration depth of chlorine ions and iodine ions in concrete under natural immersion condition. It is found that, with the same penetration depth, the cumulative deposition of iodide ions is greater than chlorine ions, and the different between them increases following the increase of w/c; with the increase of the penetration depth, the cumulative deposition amount of chlorine ions and iodine ions becomes closer; the penetration depth and the water-cement ratio are closely related, and a power function taking w/c as a variable can be used to reflect the evolution law of the penetration depth.(6)Based on the transport characteristics of iodide ions in concrete and the principles of RCM test, RIM test method which evaluates permeability of concrete using iodide ions is developed. A colorimetric depth correction factor is proposed to translate RIM test results to RCM results. It has been proved that, RIM method can be effectively used to evaluate the permeability of concrete containing interior chloride ions.更多还原