Sodium sulfate attack on Portland cement structures: experimental and analytical approach

Abstract The industrial development and the advance of the primary sector in Brazil generated an increase in the cases of structures damaged by sulfate attacks. A reduction in material lifetime is one of the most costly factors in the construction field. Therefore, it is necessary to understand the sulfate attack mechanism in order to provide repairs and prevent further attacks. This article aims to understand how the environmental condition and the material properties influence the attack’s severity. Hence, it combined an experimental program and analytical model to measure those parameter effects. Experiments show that cement with a higher amount of tricalcium aluminate (C3A), as the CP V ARI, presented a more pronounced deterioration. Visual changes such as cracking, crystallization of expansive products and a complete disintegration were also observed. In addition, loss of resistance occurred in the specimens with low slag content. Moreover, the model is useful to predict the delamination depth and to identify the most critical factors influencing the attack through sensitive analysis. Its results were compared with real cases based on literature and verifying the model reliability.

摘要 巴西的工业发展与第一产业进步导致硫酸盐侵蚀破坏的工程结构案例逐年增多。结构材料服役寿命缩短是建筑工程领域最具成本消耗性的问题之一。因此，为开展修复工作并预防后续侵蚀，明确硫酸盐侵蚀的作用机理是十分必要的。本文旨在探究环境条件与材料属性对硫酸盐侵蚀严重程度的影响机制。为此，本研究结合试验方案与解析模型，量化各参数的影响效应。试验结果表明，铝酸三钙（tricalcium aluminate，C3A）含量较高的水泥（如CP V ARI型水泥）会表现出更显著的劣化现象；同时还观测到开裂、膨胀产物结晶以及完全崩解等宏观外观变化。此外，矿渣掺量较低的试样出现了力学性能损失。该模型可通过敏感性分析预测脱层深度，并识别出对侵蚀过程影响最大的关键因素。研究将模型预测结果与文献中的实际工程案例进行对比，验证了模型的可靠性。