Living Reference Work Entry

Handbook of Sol-Gel Science and Technology

pp 1-24

Date: Latest Version

Alkaline Silicate Solutions: An Overview of their Structure, Reactivity, and Applications

  • L. VidalAffiliated withSPCTS, University of Limoges Email author 
  • , A. GharzouniAffiliated withSPCTS, University of Limoges
  • , S. RossignolAffiliated withEcole Nationale Superieure de Ceramique Industrielle–Limoges


Alkaline silicate solutions have many applications, including sand agglomeration and geopolymer production. To ensure the widespread use of these applications, it is necessary to identify the parameters controlling their reactivity and interactions with other materials, such as sand and metakaolin. It has been evidenced that the key parameters for solution reactivity are the Si/M molar ratio and the water contents. The most reactive alkaline solutions have alkali cation concentrations ranging from 4.5 to 9.5 mol/L. For the sand agglomeration application, it was shown that the used solutions are highly polymerized. In addition, the drying temperature and the method employed influence the silicate distribution in the final material. For geopolymer formation, it was evidenced that a highly reactive alkaline solution favors the formation of a geopolymer network by increasing the formation rate of Al(IV) up to 80 %, which improves the working properties of the final materials. Thus, knowledge of the key parameters controlling the alkaline silicate solution reactivity is important to determine the appropriate solution for a given application.