Drying shrinkage and microstructure of alkali-activated slag with different mixing time at low temperatures (-5 to 5 °C)

The large shringkage of alkali-activated slag (AAS) mixed at room temperature limits its broader application. In this work, the drying shrinkage and microstructure of AAS prepared using various mixing times at low temperatures (-5, 0, and 5 degrees C) were studied. The results show that the drying shrinkage of AAS mortars was strongly dependent on the mixing time at low temperatures. At-5 degrees C, the drying shrinkage of AAS mortars decreased with increased mixing time. In comparison to the AAS mixed at room temperature, the decrease in drying shrinkage is explained by a longer mixing time that induced the rearrangement of nanostructure of the prepared material and led to the formation of more hydrotalcites, and a short-chain structure of the calcium-sodium-alumina-silicate-hydrate (C-N-(A)-S-H) gels formed in the AAS mortar.