Physical and chemical processes of volcanic rock hardening with alkaline silicates

Abstract

The thermodynamic probability of reactions in volcanic rock compositions — an alkaline silicate binder, which is used to produce artificial stone (concrete) products with high physical and mechanical properties and with wide range of colors for interior and exterior wall tiling and external masonry, manufacturing of decorative architectural details, etc. are considered. Silicate and aluminosilicate rocks of volcanic origin (perlite, pumice, tuff, etc.) of various deposits of Armenia are dispersed volcanic glasses with feldspar inclusions and are characterized by a large variety of colors: white, beige, yellow, orange, violet-pink, pinkish, red, brown, black, greenish, bluish-white, etc. Dolomite hardener is introduced into the composition for manufacturing of waterproof concrete on a base of a chemical binder at low temperatures.The possibility of reactions in a mixture of volcanic rock – alkaline silicate – dolomite – water was assessed by thermodynamic method. The calculation of Gibbs energy of the interaction reactions in the indicated system witnessed the possibility of realization of hydration, hydrolysis, silicate formation reactions even at a temperature of 298K.The formation of hydrated silicates and calcium and sodium aluminosilicates, guarantees the binding properties of the composition under normal conditions. With an increase of the temperature to 375, 475, 574K, the probability of reactions increases.