Abstract Organic coatings have been widely used to protect concrete structures from the aggressive environment and improve their reliability. However, there is a lack of clear understanding on how environmental stressors contribute to the degradation and, ultimately the loss of protection function of organic coatings. In this study, comparative degradation studies were carried out on two kinds of coatings, namely polyurea and epoxy coatings, with the major focus on the relationship between their bulk degradation, loss of adhesion and the deterioration of protection performance. Samples were all subjected to ultraviolet (UV)-condensation exposure up to about 1440 h. The changes in the surface morphology, internal pore structure, wettability and chemical structure of aged coating surface were characterized via scanning electronic microscopy (SEM) laser scanning confocal microscopy (LSCM), static contact angle measurements, and Fourier Transform Infrared Spectroscopy (FT-IR) respectively, while the water resistance and adhesion strength between coatings and concrete were studied by water sorption and pull-off tests separately. The results showed that UV irradiation induced significant morphological and chemical changes in the epoxy coatings, while the changes in the polyurea coating were minor. However, due to the higher loss in adhesion, it was interestingly found that the chloride resistance of polyurea coating was reduced even more pronouncedly than that of epoxy coating after aging. This study has clearly demonstrated the strong dependence of the protection performance of coatings for concrete on their adhesion loss besides the bulk degradation induced by the aging process.

中文翻译：

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混凝土有机涂料紫外线降解的比较研究：结构、附着力和防护性能

摘要 有机涂层已被广泛用于保护混凝土结构免受侵蚀性环境的影响并提高其可靠性。然而，对于环境压力因素如何导致有机涂层降解并最终丧失保护功能，目前还缺乏明确的认识。在这项研究中，对两种涂料，即聚脲和环氧涂料进行了比较降解研究，主要关注它们的整体降解、附着力丧失和防护性能恶化之间的关系。样品均经受紫外线 (UV) 冷凝暴露长达约 1440 小时。表面形貌、内部孔隙结构的变化，老化涂层表面的润湿性和化学结构分别通过扫描电子显微镜 (SEM) 激光扫描共聚焦显微镜 (LSCM)、静态接触角测量和傅里叶变换红外光谱 (FT-IR) 进行表征，而耐水性和附着强度分别在涂料和混凝土分别通过吸水和拉拔试验进行研究。结果表明，紫外线照射引起环氧涂层显着的形态和化学变化，而聚脲涂层的变化很小。然而，由于附着力损失较大，有趣的是发现聚脲涂层的耐氯化物性在老化后比环氧涂层的降低更显着​​。