Insights into the mechanism of the chemically initiated setting of potassium silicate solutions with aluminum metaphosphates. Correlation of the structural and macroscopic parameters on the performance of the binding properties

Abstract

In this study the interaction of the chemically initiated setting of potassium silicate solutions with aluminum metaphosphates was investigated in terms of the structural analysis. The mechanism occurs in a multi-step reaction involving the depolymerization of the cyclic phosphate structure yielding to different phosphates and hydrogen phosphate structures which mainly are formed with potassium ions of the silicate solution. The setting of the potassium silicate solutions is activated by the loss of potassium ions which drop of pH value which initiates the cross connection of the silicate framework. At the same time aluminum ions are incorporated into the setting of the amorphous alumosilicate silicate network. Correlating the phase composition in respect to the alkali modulus of the potassium silicate solution and the ring size of the aluminum metaphosphate gives an insight into the performance of the binder system.