Effects of a novel polymer-type shrinkage-reducing admixture on early age microstructure evolution and transport properties of cement pastes

摘要

A novel polymer-type shrinkage-reducing admixture (SRA) with promising shrinkage-reducing and water-reducing functions was developed recently. However, its effects on the early age properties of cement pastes which determine the long term durability of concrete structure still remain unclear. This study aims to investigate its effects on the early age microstructure evolution and transport properties of cement paste. Comparative studies between this novel SRA and traditional SRA were carried out in terms of their influence on the early age hydration, capillary pressure, electrical resistivity and the strength of the cement pastes. The results show that with the presence of the novel SRA, hydration and microstructure development were slowed down together with an increase of the transport-related properties while the mechanical properties were declined slightly due to the higher capillary porosity compared to the traditional SRA. Larger Kelvin's radium in the novel SRA system was found, which would cause faster water evaporation after exposing to dry conditions, suggesting that special care needs to be taken in the early curing.