Shrinkage, mechanical properties and freeze-thaw resistance of cement mortar containing internal curing materials with different absorption behaviors at low humidity

Abstract

Cement-based materials with addition of superabsorbent polymer have attracted widespread attention due to their excellent shrinkage resistance and durability. This paper investigated the effects of three internal curing materials with different swelling behavior on mortar related shrinkage, corresponding durability at 50% humidity. The composite microgel with high water retention and controllable water release kept the relative humidity inside the mortar at a high level, and the total shrinkage in the low humidity condition decreased by 126.22 µm/m compared with the reference sample. The correlation analysis showed that the composite microgel reduced the autogenous shrinkage of mortar at the early hydration stage, and significantly alleviated the drying shrinkage with the reduction of internal relative humidity. Composite microgel compacted the microstructure of mortar, and compressive strength is higher than that of microgel modified mortar. At the same time, the role of composite microgel in refining microstructure prevented the water penetration of mortar, and the freeze-thaw resistance of mortar can be better improved by entrained air void of composite microgels.