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Influence of the water absorption-release processes of superabsorbent polymer with varying amounts of extra-entrained water on the surrounding cement paste
Cement and Concrete Composites ( IF 10.8 ) Pub Date : 2025-01-27 , DOI: 10.1016/j.cemconcomp.2025.105953
Fangyu Chen, Jingjing Lyu, Xinchun Guan, Jing Qiao, Heqing Gou

This paper investigates the influence of the water absorption-release process of superabsorbent polymer (SAP) with varying amounts of extra-entrained water on the properties of the surrounding cement paste and the macroscopic cement paste. 1H low-field nuclear magnetic resonance (NMR) was used to analyze the water absorption-release process of SAP. The macroscopic properties, including the void system, compressive strength, and autogenous shrinkage, were systematically examined. Furthermore, the degree of hydration, pore structure, and microscopic mechanical properties were investigated using large particle-size SAP (5 mm) to expand the internal curing zone. The results indicate the existence of an “equilibrium point” in the absorption-release process of SAP within cement paste. When exceeding the “equilibrium point”, the free water in the SAP is rapidly released, leading to an increase in the local water-cement ratio. This results in a looser pore structure and a reduction in the micro-mechanical properties of the internal curing zone, ultimately weakening the compressive strength. Conversely, when below the “equilibrium point”, SAP absorbs water, reducing the water-cement ratio, compacts the pore structure, and enhances the micro-mechanical properties of the internal curing zone. This improvement compensates for the reduction in compressive strength caused by voids. Additionally, when the extra-entrained water is below the “equilibrium point”, the more water entrained in SAP, the higher the gel and capillary water content, resulting in a greater reduction in autogenous shrinkage. However, when exceeding the “equilibrium point”, the content of gel and capillary water does not increase further, and autogenous shrinkage will not decrease any further.

中文翻译:


不同量额外夹带水的高吸水性聚合物的吸水-释放过程对周围水泥浆的影响



本文研究了不同额外夹带水的高吸水性聚合物 (SAP) 的吸水-释放过程对周围水泥浆和宏观水泥浆性能的影响。采用 1H 低场核磁共振 (NMR) 分析 SAP 的吸水-释放过程。系统地检查了宏观特性,包括空隙系统、抗压强度和自体收缩。此外,使用大粒径 SAP (5 mm) 研究水合度、孔隙结构和微观机械性能,以扩大内部固化区。结果表明,水泥浆中 SAP 的吸收-释放过程中存在“平衡点”。当超过“平衡点”时,SAP 中的游离水会迅速释放,导致局部水灰比增加。这导致孔结构更松散,内部固化区的微观机械性能降低,最终削弱了抗压强度。相反,当低于“平衡点”时,SAP 会吸收水分,降低水灰比,压实孔隙结构,并增强内部固化区的微观机械性能。这种改进补偿了空隙引起的抗压强度降低。此外,当额外夹带的水低于“平衡点”时,SAP 中夹带的水越多,凝胶和毛细管含水量就越高,从而导致自体收缩的减少幅度更大。然而,当超过“平衡点”时,凝胶和毛细管水的含量不会进一步增加,自体收缩也不会进一步减少。
更新日期:2025-01-27
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