Exploring the role of SAP chemical composition in the internal curing of high-performance cementitious materials

• Published in: Construction & building materials Vol. 451; p. 138784
• Main Authors: Li, Yasen, Zhang, Cheng, Li, Tingzhong, Sun, Guoxing
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.11.2024
• Subjects: Chemical structure; High-Performance Cementitious Materials; Sulfonic acid group; Superabsorbent Polymer (SAP); High-Performance Cementitious Materials; Superabsorbent Polymer (SAP); Sulfonic acid group; Chemical structure
• ISSN: 0950-0618
• DOI: 10.1016/j.conbuildmat.2024.138784

This study investigates the impact of the chemical composition of superabsorbent polymers (SAPs) on their effectiveness in internal curing within high-performance cementitious materials. Although the use of commercial SAPs in cementitious systems has been widely researched, there is still no consensus on how different SAP structures influence material properties. For the first time, this research employs photoinitiated free radical polymerization technology to synthesize three structurally distinct SAPs: SAP with sulfonic acid groups (PAMPS), SAP with amide groups (PAM), and SAP with carboxyl groups (PAAs). The effects of these SAPs on the cement hydration process and microstructure were examined by analyzing their water absorption behavior in cement filtrate. The residual cation content on the SAP surface was evaluated using EDS, while XRD and TGA were used to study how SAP structure affects cement hydration products. Furthermore, the impact of these SAPs on the strength and autogenous shrinkage of the material was investigated. The results indicate that PAMPS, with its sulfonic acid groups, exhibited stable water absorption performance in the alkaline cement environment, promoting hydration reactions and increasing the formation of needle-shaped C-S-H. This stability contributed to mitigating the negative effects on mechanical properties. While the inclusion of SAPs generally reduced the strength of the cement matrix, PAMPS was the most effective in mitigating autogenous shrinkage, achieving a shrinkage mitigation efficiency of 86 %. These findings highlight the importance of SAP chemical structure in influencing cement hydration and material performance, offering insights for the development of effective internal curing agents to enhance high-performance concrete. •Sulfonic acid-based SAP (PAMPS) maximizes water absorption in cement environments.•PAMPS accelerates hydration, forming needle-shaped C-S-H gels.•PAMPS mitigates cement autogenous shrinkage, enhancing durability.•Study guides SAP optimization for high-performance concrete.