The purpose of this study is to investigate the effects of sulfate exposure on the mechanical behavior of fresh-to-fresh composite systems (CS), incorporating self-compacting concrete (SCC) in compression and engineered cementitious composites (ECC) in tension. ECCs were designed based on various supplementary cementitious materials (SCM) such as low and high calcium fly ash, slag and reinforcing fibers such as PVA and steel fibers. Repeated cycles of immersion in concentrated sodium sulfate solution were followed by drying at high temperatures (80 °C). After 90 and 180 days of cyclic exposure, the mechanical properties including flexural, compressive and tensile bond strength and mass change were evaluated. To investigate microstructural deterioration and reaction product concentration, SEM-EDS and backscattered electron imaging were used to examine sulfate profiles at the interfacial zone between SCC and ECC. Composite samples demonstrated excellent physico-mechanical resilience. The incorporation of low calcium fly ash and slag was observed to have a beneficial impact on residual mechanical properties in long-term exposures, along with the de-passivation capacity of the reinforcing fibers. No physical de-bonding was observed in any CS, however phase assemblages revealed high concentrations of reaction products in the SCC layers near the interfacial bond with the ECC layers.

中文翻译：

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辅助胶凝材料和纤维增强材料在增强 SCC/ECC 复合材料体系抗硫酸盐侵蚀性方面的作用

本研究的目的是研究硫酸盐暴露对新鲜复合材料系统 (CS) 力学行为的影响，其中包括压缩状态下的自密实混凝土 (SCC) 和拉伸状态下的工程水泥复合材料 (ECC)。 ECC 是基于各种辅助胶凝材料 (SCM) 设计的，例如低钙和高钙粉煤灰、矿渣和增强纤维（例如 PVA 和钢纤维）。重复浸泡在浓硫酸钠溶液中，然后在高温（80°C）下干燥。循环暴露 90 天和 180 天后，评估机械性能，包括弯曲、压缩和拉伸粘合强度以及质量变化。为了研究微观结构恶化和反应产物浓度，使用 SEM-EDS 和背散射电子成像来检查 SCC 和 ECC 之间界面区域的硫酸盐剖面。复合材料样品表现出优异的物理机械弹性。据观察，低钙粉煤灰和炉渣的掺入对长期暴露中的残余机械性能以及增强纤维的去钝化能力具有有益的影响。在任何 CS 中均未观察到物理脱粘，但相组合显示在与 ECC 层的界面键附近的 SCC 层中存在高浓度的反应产物。