Effect of internal curing by superabsorbent polymers on the densification and microstructural development of cementitious materials exposed to different environmental conditions

• Published in: Construction & building materials Vol. 411; p. 134778
• Main Authors: Hong, Geuntae, Kim, Jiyoung, Song, Chiwon, Yeon, Jung Heum, Choi, Seongcheol
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 12.01.2024
• Subjects: Compressive strength; Internal curing; Microstructure; Permeability; Superabsorbent polymer (SAP); Ultrasonic pulse velocity (UPV); Compressive strength; Permeability; Microstructure; Superabsorbent polymer (SAP); Ultrasonic pulse velocity (UPV); Internal curing
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2023.134778

Superabsorbent polymers (SAPs) are among the internal curing agents used in cementitious materials. This study aims to evaluate the influence of wider SAP dosages under different exposure environments on the microstructural densification of cementitious materials and the development of strength and durability based on this. With SAP incorporation, hydrate crystallization most easily occurs in the wet/dry condition through hydration with externally supplied water and by internal SAP curing, which leads to the formation of the densest microstructures. Microstructure densification further progresses as the SAP dosages increase. Despite the internal curing effect of SAPs, the ultrasonic pulse velocity and the compressive strength of S0.5 specimens compared with those of the REF specimens decrease due to SAP void presence. However, these mechanical properties of the S1.0 specimens are all recovered at later ages when exposed to the wet/dry condition, forming densest microstructures. As the SAP dosages increase, the sealing effect of SAPs improves the water permeability characteristics at early ages. The lowest water permeability coefficient is observed in the S1.0 specimen exposed to the wet/dry condition as the further hydration effect of SAPs is exerted with increasing ages. In conclusion, utilizing the appropriate amount of SAPs and environmental conditions can effectively densify the internal pore structures, thereby securing the mechanical and durable properties of concrete structures. •Influence of three environmental conditions on internal curing effect of SAPs was studied.•The densest microstructures of SAP-internally cured mortars were formed in the wet/dry condition.•The collapse of micropores was alleviated by the internal curing of SAPs.•1.0% of SAP incorporation and the wet/dry condition induced efficient sealing of internal pore structures and further hydration by SAPs.