Effects of type and dosage of alkaline activator and temperature on the properties of alkali-activated slag mixtures

In this paper the results of a study on the influence of sodium hydroxide, sodium carbonate, and sodium silicate, as activators, and temperatures in the range of 20–31 °C on the setting time and workability of the fresh alkali-activated slag cement (AAS) mixtures are presented. The results obtained show a significant acceleration of the setting of the AAS mixtures versus the setting of ordinary Portland cements. The highest acceleration of the setting was found with sodium silicate, while both sodium hydroxide and sodium carbonate show a moderate effect. The increase of temperature of the mixtures shows the acceleration of setting and decrease of workability. At the sodium silicate a continuous effect was observed as temperature was increased. But with sodium hydroxide and sodium carbonate a sudden acceleration of the setting, and workability decrease were observed, when the temperature reached the values 24–29 °C.