Effect of silica fume on efflorescence formation and alkali leaching of alkali-activated slag. (15th September 2021)

• Record Type: Journal Article
• Authors: Saludung, Apriany; Azeyanagi, Takumu; Ogawa, Yuko; Kawai, Kenji
• Is Part Of: Journal of cleaner production. Volume 315(2021)
• Publication Date: 2021-09-15
• Subjects: Alkali-activated slag -- Alkali leaching -- Blast-furnace slag -- Efflorescence -- Silica fume; Factory and trade waste -- Management -- Periodicals; Manufactures -- Environmental aspects -- Periodicals; Déchets industriels -- Gestion -- Périodiques; Usines -- Aspect de l'environnement -- Périodiques; 628.5
• DOI: 10.1016/j.jclepro.2021.128210
• Languages: English
• ISSNs: 0959-6526

Abstract

Abstract: Alkali-activated cements (AACs) produced from industrial by-products have attracted great attention as an alternative to Portland cement, mainly because of the reduction of carbon dioxide emission and low energy consumption. However, AACs often suffer from severe efflorescence when subjected to humid environments because of their high soluble alkali content. This study reports the effect of silica fume on alkali leaching and efflorescence formation of alkali-activated slag. Specimens were prepared from ground granulated blast-furnace slag (BFS) and silica fume, where sodium hydroxide and sodium silicate solution were employed as activator solutions. Sample produced from 100% BFS exhibited the fastest efflorescence formation and alkali leaching rate. Incorporating silica fume into alkali-activated slag reduced the mobility of alkali, resulting in the decrease of efflorescence formation. However, almost all sodium can be leached out from the samples after immersion in water for 28 d, indicating the weak bond of sodium in the gel. Highlights: The alkali leaching test was performed to assess the efflorescence potential in alkali-activated slag. The inclusion of silica fume reduces the alkali leaching rate and efflorescence formation. Efflorescence product was confirmed by XRD analysis.