Highly absorptive normal weight aggregates for internal curing of concrete

The objective of this research was to develop an internal curing (IC) approach aiming to reduce early-age shrinkage and maintain the materials properties intact. Attention was given on delivering curing water within the material's structure using existing constituents of the mixture. Highly absorptive normal weight aggregates (HANWA) were employed to deliver water for IC within the material's structure. Concrete mixtures including dry and saturated HANWA were compared with ordinary (low-absorptive) normal weight aggregates (NWA) in order to evaluate the IC effectiveness. Furthermore, superabsorbent polymers (SAP) were employed also for IC and evaluated in mixtures with NWA. The mixtures were compared in terms of autogenous shrinkage, compressive strength, chloride diffusivity, open porosity and restrained shrinkage. It has been shown that HANWA material can be used effectively as an IC agent in order to reduce early-age shrinkage and at the same time maintain the mechanical properties and durability of concrete.