The use of superabsorbent polymers in cement-based materials is focused in the mitigation of autogenous phenomena. Hence, by providing the necessary water to control the volume change occurring at early-age, the deformation of cement-silica paste is controlled, as measured by linear displacement methods. The mechanisms of internal curing in high performance cement-based materials are poorly understood. The present study will bring into perspective several aspects related with the water movement from superabsorbent polymer particles with varying diameter size to the surrounding cement paste, by examining the water state in water-entrained and non water-entrained cement-silica pastes. The effect of size of superabsorbent polymer particles on autogenous deformation is analysed by linear dilatometer measurements and the relation between expansion and shrinkage with the water state in time is discussed. The results indicate that superabsorbent polymers are able to imbibe the bulkpaste, but the particle size may have significant effect on the subsequent deformation. It is proposed that mechanical effects such as self-restraint of the pore structure may play an important role as governing mechanism in the course of the early-age deformation, after capillary suction and internal curing. As a consequence, it may be that the internal curing water may be partially kept in the superabsorbent during longer periods while diffusion to the bulk cement paste is finalised.
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