Effect of internal curing by superabsorbent polymers – Internal relative humidity and autogenous shrinkage of alkali-activated slag mortars

• The internal curing effect by SAPs was experimentally evaluated.
• The IRH and autogenous shrinkage were measured.
• The IRH and shrinkage decreased with increasing dosage of SAPs in the specimens.
• The volume fraction of the internal curing zone of the SAPs was modeled.
• The SAPs as internal curing agents are effective for both NPC and AAS mortar.

This study experimentally investigated the effect of internal curing by superabsorbent polymers (SAPs) for mitigating autogenous shrinkage of alkali-activated slag (AAS) mortars. Measured were the compressive strength, the internal relative humidity (IRH), and autogenous shrinkage of AAS mortars incorporating different dosages of SAPs. Test results showed that as the dosage of SAPs increased, the reduction of IRH owing to self-desiccation and autogenous shrinkage both decreased, indicating that the SAPs can be effectively used as internal curing agents. The resulting modeling of the internal curing zone is expected to be useful in determining the appropriate dosage of SAPs in AAS mortars.