Understanding the performance of concrete in the marine environment is significant for preventing the corrosion of chloride ion for marine buildings. In this study, the uniaxial compressive strength (UCS), chloride ion concentration (CIC), microstructure, and pore structure of admixture concretes were tested to study the mechanical properties and microscopic characteristics under the single marine corrosion, the single freezing-thawing, and the coupled marine corrosion and freezing-thawing conditions. The results indicate that the concrete mixed with both fly ash and mineral powder has better UCS, chloride ion penetration resistance, and freezing-thawing resistance than the concrete with the single fly ash or mineral powder. Under the marine corrosion environment and coupled corrosion and freezing-thawing environment, the UCS of the concrete with both fly ash and mineral powder increases firstly and then decreases with the increase of the corrosion time. This is because the pore of the filling body is filled by large crystalline salts generated by the reaction of chloride ions and concrete; then, cementation of the cement is increased in the early corrosion; meanwhile, the increase of crystal salt in the subsequent corrosion process leads to the growth of microcracks and the formation of macrocracks in concrete specimens. In addition, a freezing-thawing-corrosion composite strength impact factor is introduced to describe the effect of coupled corrosion and freezing-thawing on the mechanical property of the concrete. The results show that the corrosion is the dominant factor after 0, 30, and 60 freezing-thawing cycles, while the freezing-thawing is the dominant factor after 90 freezing-thawing cycles.

中文翻译：

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矿物腐蚀混凝土在海洋腐蚀和冻融环境下的破坏机理

了解混凝土在海洋环境中的性能对于防止氯离子腐蚀对海洋建筑具有重要意义。在这项研究中，测试了掺混混凝土的单轴抗压强度（UCS），氯离子浓度（CIC），微观结构和孔结构，以研究单一海洋腐蚀，单一冻融和热腐蚀下的力学性能和微观特性。海洋腐蚀和冻融条件的结合。结果表明，与粉煤灰或矿粉混合的混凝土比单粉煤灰或矿粉的混凝土具有更好的UCS，抗氯离子渗透性和抗冻融性。在海洋腐蚀环境以及腐蚀和冻融耦合环境下，粉煤灰和矿粉的混凝土的UCS随腐蚀时间的增加先增大后减小。这是因为填充体的孔被氯离子与混凝土反应生成的大结晶盐所填充。然后，在早期腐蚀中增加了水泥的胶结作用。同时，在随后的腐蚀过程中结晶盐的增加导致混凝土试样中微裂纹的增长和宏观裂纹的形成。此外，引入了冻融腐蚀复合强度影响因子来描述腐蚀与冻融耦合对混凝土力学性能的影响。结果表明，腐蚀是0、30和60次冻融循环后的主要因素，