Effect of retarders on flow and strength development of alkali-activated fly ash/blast furnace slag composite

摘要

Geopolymer concrete presents a major problem regarding its practical application, in that the geopolymer paste has very short setting time. Previous studies have shown that the addition of blast furnace slag to geopolymer paste considerably shortens the setting time. Based on these findings, in the present study, setting retarders were used to lengthen the setting time of the geopolymer paste. The objective of the present study was to identify the effect of a setting retarder on the fluidity and compressive strength of alkali-activated fly ash/blast furnace slag-based materials. It was shown that, by adding a chelator as a retarder, the setting time can be prolonged. However, the setting time was found to be dependent on the type of chelator. Similarly, the compressive strength development of the geopolymer was also found to be dependent on the type of chelator. It was clarified that the concentration of calcium and aluminum in solution during hardening changes with the addition of a chelator, and it was shown that there is a correlation between the concentrations of calcium and aluminum and the setting time. (C) 2019 Elsevier Ltd. All rights reserved.