Mitigation of Efflorescence and Alkali Leaching in Activated Slag Using Foundry Sand

Abstract

This research aimed to examine the impact of foundry sand on alkali leaching and the formation of efflorescence in alkali-activated slag. The activation process involved the utilization of sodium hydroxide and sodium silicate solutions in activating ground-granulated blast furnace slag (GBFS) and sand samples. The leaching of alkali and the formation of efflorescence were observed to occur at a reduced rate in samples derived solely from 100% ground granulated blast furnace slag (GBFS). In contrast, higher rates were identified in samples containing chemically bonded foundry sand. The incorporation of chemically bonded foundry sand elevated the mobility of alkali, leading to an increased formation of efflorescence in alkali-activated slag. Following a three-day immersion of the specimens in deionized water, nearly all of the sodium was leached from the samples, highlighting the limited affinity of sodium within the gel structure.