In order to investigate the deterioration mechanism of steam-cured concrete under severe environmental actions such as acid rain corrosion, salt corrosion, and cyclic thermal loading, accelerated corrosion tests were conducted in this study. Surface damage as well as deteriorative kinetics of steam-cured concrete and cement paste suffering from coupled acid-thermal actions was investigated by soaking-drying cycle experiments. The effects of mineral admixture, curing regime and corrosion condition on the durability were all comparatively studied, and the X-ray diffractograms and nanoindentation were applied to analyse the mechanism of corrosion deterioration. The results revealed that compared with the cementitious materials under standard curing, larger depth and faster corrosion were observed for steam-cured concrete and cement paste, which might be partly attributed to the lower content of hydrated production presented in steam-cured specimens. Besides, under acid solution soaking-drying cycle regime, there was significant higher corrosion depth compared to only soaking in acid solution. The corrosion depth under steam curing and soaking-drying condition increased by 156.68% and 44.17%, respectively, compared with those under standard curing and only soaking treatment. In addition, fly ash effectively decreased the corrosion depth of steam-cured cement paste and concrete by 64.98% and 16.33%, respectively.

中文翻译：

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环境酸和干燥作用共同作用下蒸养混凝土的劣化机理

为了研究蒸汽固化混凝土在酸雨腐蚀，盐腐蚀和循环热负荷等恶劣环境作用下的劣化机理，本研究进行了加速腐蚀试验。通过浸泡-干燥循环实验研究了遭受酸-热耦合作用的蒸汽固化混凝土和水泥浆的表面损伤以及劣化动力学。比较研究了矿物掺合料，固化方式和腐蚀条件对耐久性的影响，并利用X射线衍射图和纳米压痕分析了腐蚀恶化的机理。结果表明，与标准养护下的胶凝材料相比，蒸汽养护的混凝土和水泥浆具有更大的深度和更快的腐蚀速度，这可能部分归因于蒸汽固化样品中水合产物的含量较低。此外，在酸性溶液浸泡-干燥循环条件下，与仅在酸性溶液中浸泡相比，腐蚀深度明显更高。与标准固化和仅浸泡处理相比，蒸汽固化和浸泡干燥条件下的腐蚀深度分别增加了156.68％和44.17％。此外，粉煤灰有效地将蒸汽固化的水泥浆和混凝土的腐蚀深度降低了64.98％和16.33％。与标准固化和仅浸泡处理相比，蒸汽固化和浸泡干燥条件下的腐蚀深度分别增加了156.68％和44.17％。此外，粉煤灰有效地将蒸汽固化的水泥浆和混凝土的腐蚀深度降低了64.98％和16.33％。与标准固化和仅浸泡处理相比，蒸汽固化和浸泡干燥条件下的腐蚀深度分别增加了156.68％和44.17％。此外，粉煤灰有效地将蒸汽固化的水泥浆和混凝土的腐蚀深度降低了64.98％和16.33％。