Abstract Numerous researches have reported that there is a tendency chloride content first climbs to the maximum then declines with depth increasing in the surface layer of concrete under cyclic drying-wetting environments, which is temporally called ‘maximum phenomenon’ in this paper. This research focuses on the impact of different carbonation conditions on this phenomenon for both pastes and mortars. The distribution of chloride suggests that coupled effect of carbonation and capillary suction/moisture evaporation is more likely to lead to the formation of maximum phenomenon than the merely effect of capillary suction/moisture evaporation. Furthermore, analysis of pore structure and phase composition reveals that this particular phenomenon is directly related to the release of bound chloride fixed in Friedel's salt triggered by carbonation. In addition, the forming process of maximum phenomenon is proposed in the end based on Friedel's salt decomposition under cyclic drying and wetting condition.

中文翻译：

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循环干湿条件下碳化对试样表层“最大现象”的影响

摘要 大量研究表明，在干湿循环环境下，随着混凝土表层深度的增加，氯化物含量呈先上升至最大值后下降的趋势，本文暂称“最大值现象”。这项研究的重点是不同的碳化条件对糊状物和砂浆的这种现象的影响。氯化物的分布表明，碳化作用和毛细管吸水/水分蒸发的耦合作用比单纯的毛细管吸水/水分蒸发作用更可能导致最大现象的形成。此外，对孔结构和相组成的分析表明，这种特殊现象与由碳化引发的固定在弗里德尔盐中的结合氯化物的释放直接相关。