Mitigation on the shrinkage properties of ultra-high strength concrete via using porous coral sand and shrinkage reducing agent. (1st October 2022)

• Record Type: Journal Article
• Authors: Cheng, Shukai; Wu, Ziyang; Wu, Qiaoyun; Chen, Xuyong; Tu, Yanping
• Is Part Of: Journal of building engineering. Volume 57(2022)
• Publication Date: 2022-10-01
• Subjects: Ultra-high strength concrete (UHSC) -- Porous coral sand aggregates (PCSA) -- Shrinkage reducing agent (SRA) -- Autogenous shrinkage -- Pore structure; Building -- Periodicals; 690.05
• DOI: 10.1016/j.jobe.2022.104861
• Languages: English
• ISSNs: 2352-7102

Abstract

Abstract: This work used porous coral sand aggregate (PCSA) and shrinkage reducing agent (SRA) in hybrid systems in order to compensate high shrinkage of ultra-high strength concrete (UHSC). Accordingly, the flowability, setting times, mechanical properties autogenous shrinkage and drying shrinkage of UHSC incorporating PCSA and SRA were studied. Moreover, Scanning electron microscopy (SEM) and Mercury intrusion porosimeter (MIP) were used to characteristic the microstructure development. The results showed that pretreated PCSA improved the fluidity and compensate the autogenous and drying shrinkage, while it decreased the compressive strength of UHSC. The addition of SRA exhibited similar trend. The hybrid system of PCSA and SRA were beneficial to the fluidity and compensated the autogenous and drying shrinkage significantly, whereas it had slightly adverse effect on the compressive strength of UHSC. It was also found that, due to the synergistic effects of internal curing by PCSA and reduction effect by SRA, the dense microstructure and increased of the distribution of large capillary pores in UHSC were effectively mitigation on the autogenous shrinkage. Overall, the specimens with 45% PCSA and 1.0% SRA had the minimum autogenous and drying shrinkage. Highlights: Synergistic effects of PCSA and SRA on the mechanical and shrinkage properties of HPC are investigated. The effects of delay releasing SRA combined with PCSA on the autogenous shrinkage and drying shrinkage in HPC is studied. Reducing the fine pores in PCSA/SRA samples leads to a reduction of autogenous shrinkage for HPC. 45% pretreated PCSA combined with 1.0% SRA solution is recommended to compensate shrinkage of HPC.