"Вестник МГСУ"

The authors argue that a dry mixture composed of caustic magnesite and a microsilica additive represents a binding material which contributes to formation of a durable and water resistant artificial stone. The results of the research of the artificial stone performed through the application of the Fourier IR spectroscopy method are provided. Interaction between magnesium oxide (MgO) as the basic oxide and microsilica as an acidic oxide is proposed. This interaction makes it possible to add water to Sorel cement instead of the magnesium chloride (MgCl2) solution.
Compressive strength of the dry mix containing 10 % of microsilica has been measured. In the event of hydraulic hardening, the compressive strength of the dry mix is 11.5 MPa, while the compressive strength of the water-saturated mix is equal to 12.0 MPa. In the aftermath of the air-setting procedure, the compressive strength of the dry mix is 10.0 MPa, while the compressive strength of the water-saturated mix is 21.0 MPa. The IR spectra of the specimen exhibit vibrations at 1100-400 cm-1 that correspond to the area of Si-O and Si-O-Me stretching vibrations, a peak at 1121-1119 cm-1 that can be assigned to Si-O-Si bond vibrations, and a peak at 474-472 characteristic of Si-O-Mg stretching vibrations. The areas of 3700-3000 cm-1 and 1650-1600 cm-1 are assigned to stretching and deformational vibrations of OH groups, respectively.

The article covers the formation of the pore structure of cement systems that harden at low and negative temperatures. Temperature fluctuations that accompany the hydration of cement systems can produce a substantial impact onto the chemical activity of the water in the course of hydration. These factors can produce an adverse impact on the formation of the structure of the cement stone and impair its performance characteristics. The formation of the structure of cement systems is dependent on the impact of specialized additives, including antifreeze agents that facilitate hydration at low and negative temperatures. The research of their action and the nature of their influence on the formation of the microstructure of the cement stone facilitate the purposeful adjustment of their properties. Therefore, modification of cement systems by specialized antifreeze components is a relevant objective of scientific and practical research.
Research of a classical cement system (a benchmark composition) and a cement system modified by a specialized antifreeze polymer-based additive (a modified composition) was performed to identify the impact of antifreeze additives onto the process of formation of its pore space.
Upon completion of the research project described in the article, the authors have concluded that antifreeze additives facilitate hydration of cement at low and negative temperatures and cause regular formation of the pore structure of the cement stone.

The authors demonstrate that the use of the dry mix that constitutes caustic magnesite and a micro-silica additive makes it possible to obtain a binding material that contributes to formation of a durable and water-resistant artificial stone. The results of the research performed through the employment of methods of Fourier IR spectroscopy and electronic microscopy are provided. Interaction between magnesium oxide (MgO) as the basic oxide and micro-silica as the acidic oxide is proposed.
The compressive strength of the dry mix containing 16.7 % of micro-silica has been measured. In the event of hydraulic hardening, the compressive strength is equal to 11.5 MPa and 12.0 MPa in dry and water-saturated states, respectively. In the aftermath of air setting, the compressive strength is 10.0 MPa and 21.0 MPa in dry and water-saturated states, respectively.
Thereafter, the dry mix is gaged by the sulfuric acid solution (10 %) to identify the pH influence. In the event of hydraulic hardening, the compressive strength is 19.8 MPa and 14.1 MPa in dry and water-saturated states, respectively. In the aftermath of air setting, the compressive strength is 18.0 MPa and 19.9 MPa in dry and water-saturated states, respectively.