Utilisation of water quenched slag as fine aggregate in alkali activated mortar

This study investigates the performance of water-quenched slag (WQS) fine aggregate in blended ground granulated blast furnace slag (GGBFS) and fly ash (FA) alkali-activated materials (AAM). Mortar samples derived from the corresponding concrete mix proportion were synthesised in this study, where river sand and WQS constituted the fine aggregate system in different proportions. Analysis of workability, rheological properties, mechanical properties, shrinkage, and microstructure were carried out. The results showed that the workability of AAM, setting time, and flowability deteriorated with an increase in WQS aggregate. AAM samples witnessed higher viscosity with increasing WQS, and a certain amount of WQS added bonds and mechanical force between particles to make mortars flow at a suitable rate. Shrinkage testing included both autogenous shrinkage during the first three days and drying shrinkage during the following 360 days. WQS had an effect on shrinkage due to physical properties such as irregular grain shape and rough surface, however, high shrinkage was also attributed to pore structures. Although WQS is conducive to improvement of microstructures, too much WQS as fine aggregate in AAM deteriorates the microstructures.