This article presents the results of an investigation of the compositional and structural features of an inorganic polymer synthesized from amorphous silica and KOH. The inorganic polymers were characterized using Fourier transformation infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and X-ray diffraction (XRD). FT-IR investigation of the inorganic polymers showed that an increase in the hydroxide concentration used in the synthesis shifts the position of the maximum absorbance of Si-O bands toward lower wave numbers, indicating the transformation of Q 4 units to Q 3 and Q 2 units. XPS investigation of the inorganic polymers showed that the total amount of oxygen and potassium present in the sample increased when higher concentrations of hydroxide were used in the synthesis. The O/Si ratio of the inorganic polymers changed from 2 to 2.6 when the KOH concentration was increased from 0.75 to 4 M. The increase in the O/Si ratio can be explained by the greater dissolution of SiO 2 particles leading to the formation of branched polymers and gelation.

In this work an inorganic polymer is developed based on Elkem microsilica and potassium hydroxide. Using experimental data and the partial charge model a model for the gelation is suggested based on the hydrolysis and condensation reactions occurring during synthesis. In addition the optimal composition of the binder system was determined using compressive strength test and solubility experiments. Based on partial charge calculations and experimental data for the hydroxide concentration and the viscosity obtained in this study it is suggested that the polymerization of the inorganic polymer is determined by the concentration of silica species. It was found that the alkalinity has a crucial effect on the condensation process. The optimal potassium hydroxide concentration used in the synthesis of the inorganic polymer was found to be around 3.5 M, which resulted in a compressive strength of the product in the region of 50 MPa.