Thermodynamic difficulties to determine a critical chloride threshold for breakdown of the protective layer of steel reinforcement in a maritime concrete structure
Thermodynamic difficulties to determine a critical chloride threshold for breakdown of the protective layer of steel reinforcement in a maritime concrete structure
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确定海上混凝土结构中钢筋保护层破坏的临界氯化物阈值的热力学困难
DOI：
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发表时间：
2021
影响因子：
4.4
通讯作者：
V. Baroghel
中科院分区：
文献类型：
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作者：
A. Soive;S. Bonnet;A. Khelidj;V. Baroghel
关于临界氯离子阈值的表达式以及钢筋混凝土保护层破坏的数值存在很大争议。事实上，这一概念表明击穿仅由保护层的溶解驱动。一个反应性的传输模型，包括溶解和沉淀的固体物质与他们的动力学，然后使用，以模拟在混凝土暴露于海水和化学降解的氧化物和氢氧化物的保护层中存在的化学降解的有害物质覆盖钢筋。数值结果证实，大多数的氧化物是结晶非常稳定，即使经过长时间的曝光，特别是在内层。这一发现表明，腐蚀起始取决于保护层的厚度和历史。这些结果也提供了一个合理的解释，为什么在文献中报道的临界氯阈值的值的广泛分散。
There is much debate on the expression used for the critical chloride threshold as well as on its value for breakdown of the protective layer of steel for reinforced concrete. In fact, this concept suggests that the breakdown is only driven by dissolution of the protective layer. A reactive transport model including dissolution and precipitation of solid species with their kinetics is then used in order to simulate the ingress deleterious substances in a concrete exposed to seawater and the chemical degradation of the oxides and hydroxides present in the protective layers covering a steel rebar. The numerical results confirm that most of the oxides are thermodynamically very stable even after a long period of exposure, especially in the inner layer. This finding suggests that corrosion initiation depends on protective layer thickness and history. These results also provide a sound explanation why a wide scatter of values of critical chloride threshold values is reported in literature.