Water distribution characteristics of capillary absorption in internally cured concrete with superabsorbent polymers

To reveal the water distribution characteristics of internally cured concrete with superabsorbent polymers (SAP) during the capillary absorption process, the relationship between capillary pressure and water content of SAP were comprehensively investigated by dewpoint evaporative method. The effects of SAP types and particle sizes on the capillary water absorption coefficient of internally cured concrete were discussed based on the water absorption weight method. A water distribution model for capillary water absorption height and saturation degree in internally cured concrete with SAP was developed and validated. Results show that the water retention capacity of SAP can be evaluated by the relationship of capillary pressure and water content. Compared with polyacrylic acid sodium SAP (SAPAA) and polyacrylic acid SAP (SAPPA), non-ionic polyacrylamide SAP (SAPAM) exhibits favorable water constraint capabilities. The capillary water absorption amount and rate of concrete was increased by SAPAA and SAPPA, while they were was reduced by SAPAM at the second stage of capillary water absorption. The capillary water absorption amount of concrete was increased with the increase of SAP mesh. The water distribution model can effectively characterize the water distribution in internally cured concrete with SAP. This study enhances our comprehension on the water retention capacity of SAP, which also provides new insights for understanding the water migration and distribution in internally cured concrete with SAP.