Method for experimentally determining N-A-S-(H) solubility

  • Trevor Williamson
  • Joonkyoung Han
  • Lynn Katz
  • Gaurav Sant
  • Maria Juenger University of Texas, Austin
Keywords: Geopolymers, Alkali-Activated Cement, Thermodynamic Models, Solubility, Cement Chemistry


Inorganic polymer binders, also sometimes called geopolymers or alkali-activated cements, can serve as an alternative to ordinary portland cement (OPC) in concrete.  The development of thermodynamic models to predict phase development and, ultimately, engineering properties, of inorganic polymer binders is an important step toward enabling their widespread use. However, such models require self-consistent solubility data of the primary phase in inorganic polymer binders, sodium aluminosilicate hydrate(s). To date, there is very little solubility information available for this phase. Here, a rigorous method for synthesizing sodium aluminosilicate hydrate(s) of controlled composition, and for measuring its solubility is presented. This approach allows complete stoichiometric control over the (initial) solution composition to elucidate directly the development of N-A-S-H composition as it relates to a given solution composition. A review of previous literature related to the solubility of other cementitious materials is presented, and the need for thermodynamic data is discussed. Finally, a sample calculation is presented for determining the solubility product (Ksp) of a laboratory synthesized sodium aluminosilicate hydrate.

How to Cite
Williamson, T., Han, J., Katz, L., Sant, G. and Juenger, M. (2019) “Method for experimentally determining N-A-S-(H) solubility”, RILEM Technical Letters, 3, pp. 104-113. doi: 10.21809/rilemtechlett.2018.63.