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31.
混凝土碳化与氯离子侵蚀共同作用研究 总被引:5,自引:0,他引:5
处于除冰盐环境和海洋大气环境中的混凝土结构将受到碳化和氯离子侵蚀的共同作用。通过盐溶液浸泡与碳化交替方式,研究了碳化作用对混凝土中氯离子扩散的影响。结果表明:碳化作用加快了混凝土中氯离子扩散速度,提高了混凝土中的氯离子含量,相对于混凝土碳化对结合氯离子的释放作用,碳化导致的混凝土微观结构重分布对氯离子扩散的加速作用占主导地位。分析了碳化混凝土中的碳化钙分布和碳化深度,结果表明,用化学试剂法测试混凝土碳化深度时,碳化与未碳化交界处位于混凝土部分碳化区,交界处碳酸钙含量变化范围为5.4%~10.8%。 相似文献
32.
混凝土部分碳化区长度的分析与计算 总被引:7,自引:0,他引:7
在数值计算的基础上,提出了混凝土部分碳化区的概念,分析了影响部分碳化区长度的因素,并给出了部分碳化区长度的计算模型。 相似文献
33.
为了准确评估混凝土碳化深度和钢筋锈蚀程度,综述了现有的一些混凝土碳化模型和钢筋锈蚀模型的特点,以工程实测数据为证,重点比较了各个模型预测值与实测值之间的差异,并讨论了该差异大小不同的原因,最后建议了不同模型的适用条件.结果可以为混凝土结构耐久性评估工作提供参考. 相似文献
34.
以钛精矿、碳和Cl2为原料,采用流态化的生产技术,通过气流加热碳使碳的比表面积大于20m2/g,把非多孔型无烟煤在流化床中与空气在500~600℃的高温下进行处理,直到形成多孔状,以380~400℃的低温的条件下,同样用流化床将钛精矿与碳进行100:30的混料后与氯气反应,能够实现四氯化钛(TiCl4)的制备。该方法解决了原料中CaO和MgO在床层中大量积累,并导致沟流出现,破坏流化状态,既避免沸腾氯化对原料的苛刻的要求,也解决了H2SO4法生产的废液环保问题。为解决攀枝花高钙、镁的钛资源利用提供了一个可行的途径。 相似文献
35.
36.
《Structure and Infrastructure Engineering》2013,9(2):99-110
Concrete structures in the atmosphere may suffer from the problem of steel corrosion induced by the carbonation process. Most of previous research on concrete carbonation problems has been performed on the macro-scale. These studies did not consider the influence of the aggregates, which should be involved on meso-scale. In order to extend the present studies on the problems of concrete carbonation from macro-scale to meso-scale, an improved method to simulate the random aggregate structure (RAS) in concrete has been proposed. This method can be divided into two steps: the process of RAS in a three-dimensional model, and the process of numerical analysis in a cross-section. In this method, the effect of the randomness on the results of RAS is analysed. Based on the mass conservation law and kinetic model of chemical reactions, a simplified numerical model of concrete carbonation is developed. The effect of the key parameters in this model such as effective diffusion coefficient of CO2 and carbonation reaction constant is discussed. The comparison of the simulations of concrete carbonation process on macro-scale and meso-scale is discussed as well. Finally, an application of the method to determine the proper composition of concrete in the practical engineering is presented. 相似文献
37.
Deborah Olukemi Olanrewaj u 《机械工程与自动化:英文版》2014,(6):505-510
Construction is one of the largest users of energy, material resources and water and it is a formidable polluter. One of the major materials used in construction is concrete and ordinary concrete contains about 12% cement which is a major producer of greenhouse gas in the world. The use of waste materials as partial replacement of cement in concrete reduces greenhouse gases, frees up land fill space, and reduces raw materials consumption. This contributes towards sustainable development, as in a sustainable society, nature is not subject to systematically increasing concentrations of substances extracted from the earth's crust. This research work explores the possibility of replacing some percentage of cement in concrete with marble sludge powder to produce lightweight concrete. This was achieved by determining the compressive strength and some hardened properties of concrete like sorptivity and carbonation with marble sludge. The results so far have been able to prove that lightweight concrete can be produced when some percentage of cement is replaced with this waste. 相似文献
38.
Since the beginning of the 20th century, in Italy as in many other countries, reinforced concrete (RC) became one of the most popular construction materials and it was used for buildings, monuments, infrastructures, etc. Several of these structures, although of recent formation, have now been included in the cultural heritage, because of their architectural or social relevance. As a consequence of the typical urban or rural exposure conditions of these buildings, they often suffer damage due to carbonation‐induced corrosion of reinforcement, such as concrete spalling or cracking or rust stains that may affect the serviceability of structures. Furthermore, chloride‐induced corrosion of reinforcement, may also concern buildings exposed to de‐icing salts or marine environments. Due to strict requirements related to the preservation of the original materials and texture, the repair of structures that belong to the cultural heritage cannot rely on the conventional repair technique, based on the replacement of carbonated concrete. Therefore, the conservation of RC buildings of the cultural heritage is a challenge, since it requires the development of specific strategies aimed at finding the best compromise between, on one hand, the restoration of structural safety and the prevention of future damage and, on the other hand, the preservation of the original materials and surfaces. This paper analyses the results of inspections carried out on several buildings, built in Italy throughout the 20th century in different micro‐ and macro‐climates, with the aim of showing their peculiarities with regard to steel corrosion and the selection of restorations strategies. 相似文献
39.
目的研究在旋转填料床中以 NaAl(OH)4 溶液和 CO2 气体为原料制备超细 Al(OH)3 的碳化反应时间. 方法通过实验考察了转速, 液体循环量, 气体流量, NaAl(OH)4 溶液初始浓度, 气液比等操作因素对碳化反应时间的影响. 结果与结论在旋转填料床中的反应大大缩短了碳化反应时间, 同时得到平均粒径为 200 nm 且分布均匀的超细 Al(OH)3 粒子. 相似文献
40.
基于遗传算法的连续碳酸化分解过程模糊优化 总被引:1,自引:0,他引:1
提出了基于遗传算法的连续碳酸化分解过程操作模式模糊优化方法.首先建立基于模糊规则和模糊推理的模型,然后以稳态误差为优化目标,应用混合编码的遗传算法同时优化模糊控制隶属度和推理规则,将获得的模糊规则应用于末槽分解率的控制,获得了良好的应用效果. 相似文献