A study on viscosity and flow behaviour of dried water glasses using an extrusion method is first reported. The rheological properties of water glass samples with water concentrations in the range from 22.2 to 36.4 wt% and also some glycerin-containing samples were studied. During extrusion of dried water glasses, the viscosity decreases significantly with increasing shear rate. Lower water concentrations lead to a more pronounced deviation from Newtonian flow behaviour. This is attributed to nonlinear flow behaviour rather than to localised viscous heating effects by mechanical deformation work. Furthermore, the effect of compsotion on the viscosity-temperature dependence is studied. The higher the water concentration, the lower the viscosity. Glycerin additions intensify this effect.
