Hydrophobic hydrogels as internal curing agent for concrete: The double benefit of super high water content and excellent anti-ion permeability. (August 2022)

• Record Type: Journal Article
• Authors: Cui, Hongyuan; Chen, Feifan; Liao, Yang; Liang, Zexuan; Luo, Lu; Wang, Xiaolin; Guo, Honglei; Zhao, Jihui; Meng, Guozhe; Ouyang, Gangfeng; Ke, Wei; Guo, Hui
• Is Part Of: Composites communications. Volume 33(2022)
• Publication Date: 2022-08
• Subjects: Hydrogels -- Concrete -- Ion-permeability -- Internal curing agent
• DOI: 10.1016/j.coco.2022.101236
• Languages: English
• ISSNs: 2452-2139

Abstract

Abstract: Owing to their high water content, conventional superabsorbent polymer (SAP) hydrogels can serve as internal curing agents for concrete fabrication. However, the hydrophilic network in such hydrogels permits ion diffusion, which induces severe steel corrosion inside concrete in the marine environment. Herein, we introduce a brand-new hydrogel, termed "hydrophobic hydrogels", for concrete curing. On one hand, these hydrogels possess super high water content (up to 99.6 wt%), which is even higher than that in normal SAP hydrogels; on the other hand, the anhydrous inhomogeneous hydrophobic structures can significantly retard or stop the ion permeation, which is significantly superior to SAP hydrogels. With ion diffusion measurement, the hydrophobic hydrogels achieve much better ion resistance than SAP hydrogels, with 2–5 orders' decrease in ion permeation rate. Among diverse hydrophobic hydrogels, the polymer's hydrophobicity and glass transition directly determine the permeation performance. Hydrogels with a more hydrophobic network and higher polymer Tg possess better anti-ion diffusion properties. At the optimal state, the poly(phenyl acrylate) hydrophobic hydrogels can completely stop the permeation process. Owing to the double benefit, the hydrophobic hydrogel cured concretes demonstrate a notable decrease in ion permeation compared to SAP hydrogel cured concrete, with only 1/20 of ion permeation to that in SAP groups with an electric flux test upon coated on the surface layers. Owing to the double benefit from super high water content and excellent anti-ion permeability, these hydrophobic hydrogels may serve as ideal candidates as concrete curing agents in the future. Graphical abstract: Image 1 Highlights: Hydrophobic hydrogels are applied as internal curing agents for concrete for the first time. The hydrophobic hydrogels possess super high water content in different aqueous media (max. 99.6 wt%). The hydrophobic hydrogels achieve much better ion resistance than conventional superabsorbent hydrogels, with up to 5 orders' decrease in ion permeation rate. Owing to the double benefit, the hydrophobic hydrogels treated concretes manifest noticeably enhanced ion resistance, with 1/20 of ion permeation to that in superabsorbent hydrogel concretes.