Properties and microstructure of alkali-activated slag cement cured at below- and about-normal temperature

• Alkali activated slag paste and mortar specimens were cured at 7–30 °C.
• Curing at below normal temperature retards the setting and shrinkage of AAS.
• Curing at below normal temperature has little influence on later strength.
• Paste becomes more compact with the increases of the curing temperature.
• AAS paste cured at below-normal temperature for long age can develop to highly compact structure.

This work experimentally investigated the effects of curing temperatures (7, 15, 20 and 30 °C) on the setting time, strength development, shrinkage, and microstructure of alkali activated slag (AAS). The results indicated that the impact of the curing temperature was much more significant on the setting time of AAS than on that of ordinary Portland cement (OPC), and 7 °C curing could prolong the initial and final setting times of AAS without significant decrease of later strength, and increase the long-term strengths. The shrinkage of AAS were slightly reduced or retarded by curing at below normal temperature. There is no significant difference in the types of hydration products in the AAS pastes cured at 7–30 °C for 28 days, whereas the paste cured for same ages became more compact with lower porosity and finer pore size distribution as the curing temperature was increased.