Influence of thermoactivation on properties of mineral additives in dry mixtures

Information on the effect of thermal activation of silicate and aluminosilicate rocks used as a filler in dry building mixtures on their reactivity of interaction with lime binder is presented. The change in the distribution of acidic Bronsted and Lewis centers on the filler surface as a result of thermal activation is shown. It was found that the number of Bronsted and Lewis acid centers on the surface of fired clays exceeds the number of the same centers on the surface of unbaked clays. The number of adsorption centers at pKa from 0 to 7 and pKa> 13 on the surface of fired diatomite is 2.435 * 10-5 mol/g, and on the surface of unbaked diatomite -1.678 * 10−5 mol/g. The heat treatment of diatomite at low temperatures (2000C and 3000C) does not significantly affect the values of the compressive strength of the mortar. An increase in the firing temperature to 7000C leads to an increase in strength characteristics up to R = 4.38 MPa. However, the greatest effect is achieved when diatomite is fired at a temperature of t = 9000C. The value of the ultimate strength in compression was R = 5.1 MPa.