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- 2015
碳化与氯盐复合作用下水泥浆体的微结构演变
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Abstract:
为了阐明碳化与氯盐复合作用下硬化水泥浆体的微结构, 基于X射线计算机断层扫描成像(X-CT)和电子探针微区分析(EPMA)技术探明了氯盐对水泥浆体碳化速率的影响, 测定了碳化作用下水泥浆体内Cl、S和Na元素的浓度分布。结果表明:氯盐可细化养护龄期为28 d的水泥浆体孔结构, 提高其密实度并减缓碳化速度;碳化作用下水泥浆体的碳化区易出现裂缝, 二氧化碳气体通过这些裂缝扩散到水泥浆体内部进行碳化, 致使水泥浆体碳化深度不均匀;碳化过程中Cl、S和Na元素向非碳化区迁移和浓缩, 初始均匀分布的元素在碳化区含量减少, 在非碳化区含量升高。 所得结论为混凝土结构耐久性设计提供科学的理论依据。 In order to clarify the microstructure of cement paste under combined effect of carbonation and chloride salt, based on X-ray computed tomography (X-CT) and electron probe micro analyses (EPMA) technologies, the impact of chloride salt on carbonation rate of cement paste was investigated and element concentration distributions of Cl, S and Na in cement paste under the effect of carbonation were measured. The results show that the chloride salt can refine the pore structures of cement paste, improve the degree of density and slow down the carbonation rate of the cement paste with maintenance period of 28 d. The cracks in carbonation district of cement paste are easily generated under the effect of carbonation, and carbon dioxide gas diffuses into the inside of cement paste by those cracks to carbonize, leading to the uneven carbonation depth of cement paste. During carbonation process, Cl, S and Na elements migrate and concentrate to the non-carbonation area, the contents of elements which are distributed in initial state uniformly decease in carbonation area and increase in non-carbonated area, thus provide the scientific basis for durability design of concrete construction. 国家自然科学基金(51278255, 51308308, 51478227); 宁波市科技计划(2013C51006, 2015A610300)
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