The results of investigations of the influence of activating additives on the sintering process of silicate ceramics have been shown. Modifiers - wollastonite (CaSiO3), gypsum (CaSO4•0,5H2O), calcium carbonate (CaCO3) - were added to the charge based on silicates in order to increase strength. The total amount of modifying additives did not exceed 1.2 wt. %. Investigation of the influence of additives on the structure and properties of porous materials based on silicates suggest that compositional structure of contacts between particles is achieved by chemical interaction of liquid phase «SiO2–Na2O» with silicate particles and products of thermal decomposition of calcium carbonate. The most interesting results are obtained by using calcium carbonate. The analysis of structure shows that the shape of initial calcium carbonate particles results in the formation of pores with a developed structure in the silicate material. Understanding the mechanism of contact formation while using additives contributed to the creation of porous materials based on silicates for sterilizing filtration of veterinary medicines.