Effects and mechanisms of the hybrid-modified SAP with calcium sulfate dihydrate on the properties of UHPC

IF 13.1 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY Cement & concrete composites Pub Date : 2025-03-01 Epub Date: 2025-01-31 DOI:10.1016/j.cemconcomp.2025.105962

Deyu Kong , Zhentao Han , Zhiyang Chen , Chenxu Ni , Haotian Wu , Yaqian Liang , Kui He , Jintao Liu

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Abstract

In the synthesis process of superabsorbent polymer (SAP), calcium sulfate dihydrate (C$H₂) dispersion in water or colloidal silica sol (CSS) was used for the modification of SAP. The effects of modification on water absorption of SAP in water or saturated calcium hydroxide (CH) solution and the impacts and mechanism of the modified SAP on the performance of UHPC were investigated. The results showed that the modification results in a significant decrease in water absorption in both tap water and saturated CH solution for the SAP with water-based dispersion, but an increase in saturated CH solution though a decrease in tap water for that with the CSS-based dispersion. The SEM observation showed that a large amount of long ettringite crystals formed around the voids left by the SAP modified with the water-based dispersion. However, few ettringite crystals but more hydration products were observed to fill in the voids and a C-S-H gel shell-structure was also found in the voids left by the SAP modified with the CSS-based dispersion. Because of these, it was interestingly found that the crack resistance was further improved and a significant improvement in both flexural and compressive strength was observed, though the internal curing effect was weakened because some internal curing water carried by the SAP was consumed during the formation of the ettringite crystals and the C-S-H gels in the voids.

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二水合硫酸钙杂化改性SAP对UHPC性能的影响及其机理

在高吸水性聚合物（SAP）的合成过程中，采用二水合硫酸钙（C$H2）分散在水中或胶体硅溶胶（CSS）中对SAP进行改性，研究了改性对SAP在水或饱和氢氧化钙（CH）溶液中的吸水性的影响，以及改性SAP对UHPC性能的影响及其机理。结果表明，改性后水基分散的SAP在自来水和饱和CH溶液中的吸水性均显著降低，而css分散的SAP在自来水中的吸水性降低，但饱和CH溶液的吸水性增加。SEM观察表明，经水基弥散改性后的SAP在孔洞周围形成了大量的长钙矾石晶体。然而，用css基分散体修饰的SAP留下的空隙中，几乎没有钙矾石晶体，而是有更多的水化产物填充，并且在空隙中也发现了C-S-H凝胶壳结构。因此，有趣的是，抗裂性进一步提高，抗折强度和抗压强度都有显著提高，尽管内部固化效果减弱，因为在钙矾石晶体和空隙中的C-S-H凝胶形成过程中，SAP携带的一些内部固化水被消耗掉了。

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来源期刊

Cement & concrete composites 工程技术-材料科学：复合

CiteScore

18.70

自引率

11.40%

发文量

459

审稿时长

65 days

期刊介绍： Cement & concrete composites focuses on advancements in cement-concrete composite technology and the production, use, and performance of cement-based construction materials. It covers a wide range of materials, including fiber-reinforced composites, polymer composites, ferrocement, and those incorporating special aggregates or waste materials. Major themes include microstructure, material properties, testing, durability, mechanics, modeling, design, fabrication, and practical applications. The journal welcomes papers on structural behavior, field studies, repair and maintenance, serviceability, and sustainability. It aims to enhance understanding, provide a platform for unconventional materials, promote low-cost energy-saving materials, and bridge the gap between materials science, engineering, and construction. Special issues on emerging topics are also published to encourage collaboration between materials scientists, engineers, designers, and fabricators.