Microstructural and micromechanical characteristics of ultra-high performance concrete with superabsorbent polymer (SAP)

In this study, the hydration product, C-S-H density, and pore structure at different layers from the drying surface were measured. Besides, the zone affected by the released internal curing water from SAP was identified by assessing the nanoindentation modulus. The results found that the SAP affected the moisture distribution and changed the evaporation and self-desiccation rates in the inner and outer layers. Such imposed moisture gradients affected the micromechanical properties of UHPC at different layers due to the change in the hydration degree of the binder, the density of C-S-H, and the pore structure of the matrix. The addition of SAP improved the hydration dynamics and transferred the LD C-S-H into HD or UHD C-S-H. As the distance from the drying surface increased, the affected zone of SAP increased from 60 to 120 μm, showing the more effectiveness of SAP at inner layers.. Authors: Liu, Jianhui [Key Laboratory for Green & Advanced Civil Engineering Materials and Application Technology of Hunan Province, College of Civil Engineering, Hunan University, Changsha 410082 (China)]; Farzadnia, Nima [Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, TN 37902 (United States)]; Shi, Caijun [Key Laboratory for Green & Advanced Civil Engineering Materials and Application Technology of Hunan Province, College of Civil Engineering, Hunan University, Changsha 410082 (China)]. Subjects: 36 MATERIALS SCIENCE; CONCRETES; DENSITY; DISTRIBUTION; EVAPORATION; HYDRATION; MOISTURE; POLYMERS; PORE STRUCTURE; POROSITY; WATER