One-part alkali-activated blast furnace slag for sustainable construction at subzero temperatures

The construction season is limited in northern countries due to the severe cold weather conditions and their detrimental impacts on concrete quality. Thus, there are excessive expenses required annually for insulation and energy-intensive heating systems for cold-weather concreting. This experimental study aimed to investigate the potential of using high-strength one-part alkali-activated blast furnace slag (AAS) in cold weather without the need for supplementary heating systems. Therefore, the impacts of different subzero curing temperatures on the hardened properties of one-part AAS mortar in comparison with cement mortar were assessed. After casting, mortars were immediately cured at a temperature of 23, -5, -10, and -20 degrees C, up to 56d. The results showed that the lower the curing temperature, the lower the UPV and compressive strength of cement and one-part AAS mortar; however when the curing period was fixed, one-part AAS mortar registered higher UPV and compressive strength than cement mortar at all curing temperatures. Owing to additional room temperature curing, the hardened properties of AAS mortar were significantly improved. The findings were further supported by microstructural and thermogravimetric analyses. (C) 2020 Elsevier Ltd. All rights reserved.