Modeling of Water Migration during Internal Curing with Superabsorbent Polymers

Abstract

The mobility of water in hardening cement paste is an important aspect in view of the effectiveness of internal curing. A mechanistic-type numerical model of cementitious materials is applied for the analysis of water migration kinetics from internal curing agents [superabsorbent polymers (SAP)] into hydrating cement pastes with a low water-to-cement ratio. It is shown that the release of curing water at early age (i.e., during approximately the first day of hydration) allows for a uniform and practically instantaneous distribution of water within the whole volume of cured paste, even if the distances for water migration are as high as 2–3 mm. The evolution of permeability as a result of the hydration process is shown to have a major impact on the mobility of water in the cement paste. The depercolation of capillary porosity may substantially inhibit the water transport. The analysis shows that a part of the water first received by the paste in the proximity of the SAP can be later redistributed to a large volume of hardening paste, even after the permeability has become very low.