Metalssi Othman Omikrine, Ragoug Rim, Barberon Fabien, Lacaillerie Jean-Baptiste d'Espinose de, Roussel Nicolas, Divet Loïc, Torrenti Jean-Michel
Laboratoire Matériaux pour une Construction Durable (UMR MCD), University Gustave Eiffel, Cerema, F-77454 Marne-la-Vallée, France.
Organisation Professionnel Prévention Bâtiment Travaux Public, 25 Avenue General LECLERC, 92600 Boulogne Billancourt, France.
Materials (Basel). 2023 Sep 1;16(17):6013. doi: 10.3390/ma16176013.
Among the most significant causes of concrete degradation is ESA (external sulfate attack). The majority of studies are currently conducted on samples that have been saturated and matured. Concrete structures, however, are exposed to the environment once the formwork has been removed. The purpose of this study is to determine what effects early exposure to external sulfates may have on degradation mechanisms. Microstructure, physical, and chemical behavior are monitored using a variety of experimental techniques, including NMR (Al and Si), ICP, XRD, MIP, and SEM. Based on expansion measurements, mature Portland cement paste, unlike the early-age case, degraded rapidly due to the presence of compressed ettringite and gypsum, highlighted by SEM analysis. During ESA, sulfate ions diffuse through the cement matrix and are bound by chemical agents. Chemical analyses indicate that the chemical mechanism varies with the duration of curing. At an early age, external sulfates and aluminates are the most important reagents. For matured cases, these reagents include external sulfates, calcium derived from CH dissolution, and aluminates derived from the total dissolution of AFm.
混凝土劣化的最重要原因之一是外部硫酸盐侵蚀（ESA）。目前大多数研究是在已饱和且成熟的样品上进行的。然而，混凝土结构在模板拆除后就会暴露于环境中。本研究的目的是确定早期暴露于外部硫酸盐可能对劣化机制产生何种影响。使用多种实验技术监测微观结构、物理和化学行为，包括核磁共振（Al和Si）、电感耦合等离子体质谱、X射线衍射、汞侵入孔隙率测定法和扫描电子显微镜。基于膨胀测量，与早期情况不同，成熟的波特兰水泥浆体由于存在压缩钙矾石和石膏而迅速劣化，扫描电子显微镜分析突出了这一点。在外部硫酸盐侵蚀过程中，硫酸根离子扩散通过水泥基体并与化学试剂结合。化学分析表明，化学机制随养护时间而变化。在早期，外部硫酸盐和铝酸盐是最重要的试剂。对于成熟的情况，这些试剂包括外部硫酸盐、由氢氧化钙溶解产生的钙以及由单硫型水化铝酸钙完全溶解产生的铝酸盐。
