Li Liangshun, Wang Yue, An Mingzhe, Yu Peiyao, Hou Xu
School of Civil Engineering, Beijing Jiaotong University, Beijing 100044, China.
Materials (Basel). 2023 Jan 20;16(3):970. doi: 10.3390/ma16030970.
Cement-based materials with a low water/binder ratio contain a high number of unhydrated cement particles, which implies that a rehydration reaction occurs when they encounter water again. This study aimed to explore how rehydration influences the macroscopic and microscopic properties of cement-based materials. The key study findings included that rehydration could still occur in cement-based materials after one year of hydration, and that the capacity for rehydration-induced repair or damage to cement-based materials depended on whether their internal pores could accommodate rehydration products. During rehydration, the compressive strength and porosity of the specimens were found to first increase and then decrease. The capillary water absorption coefficient decreased continuously over a rehydration period of 120 days. As the water/binder ratio rose, the rehydration rate first increased and then decreased. First, the influence of temperature on the rehydration rate was more noticeable when the water/binder ratio was below 0.3; second, whereas adding large amounts of fly ash and silica fume did not prove to be conducive to repairing and enhancing cement-based materials undergoing rehydration, adding slag and small quantities of silica fume, or alternatively compounding small amounts of silica fume and fly ash could improve the repair and enhancement effects of rehydration.
水灰比低的水泥基材料含有大量未水化的水泥颗粒，这意味着当它们再次遇到水时会发生再水化反应。本研究旨在探讨再水化如何影响水泥基材料的宏观和微观性能。主要研究结果包括：水泥基材料水化一年后仍可发生再水化，再水化对水泥基材料的修复或损伤能力取决于其内部孔隙能否容纳再水化产物。再水化过程中，发现试件的抗压强度和孔隙率先增大后减小。在120天的再水化期间，毛细吸水系数持续下降。随着水灰比的增加，再水化速率先增大后减小。一是当水灰比低于0.3时，温度对再水化速率的影响更显著；二是虽然添加大量粉煤灰和硅灰不利于再水化水泥基材料的修复和增强，但添加矿渣和少量硅灰，或者将少量硅灰和粉煤灰复合，可以提高再水化的修复和增强效果。
