Water resistance, frost resistance and water-repellent properties of fine-grained concrete based on composite gypsum binder

In modern architectural and design solutions for buildings appearance formation facades external finishing with fine-grained concrete (FGC) based on composite gypsum binders (CGB) continues to gain popularity instead of traditionally used Portland cement. These materials have significant advantages in regulating their setting time and hardening speed. At the same time it is necessary that FGC based on CGB provide increased strength, water resistance and frost resistance, and their surface has water-repellent (hydrophobic) properties. The article presents the results of experimental studies of the physical and mechanical characteristics of the developed fine-grained concretes based on composite gypsum binders with a mineral additive of highly active metakaolin VMK-45 and a complex of organic additives – SP Melflux 1641F + RPP Vinnapas 8034H. The results of performed studies allow us to assert that the developed water-resistant and frost-resistant MZB based on KGV class B22.5 with a hydrophobic surface can be used for external finishing of buildings and structures facades. The water-repellent properties of the hardened MZB surface are manifested mainly due to the use of a chemical additives complex, which action principle is based on combination of electrostatic and steric repulsion, effect achieving with the help of lateral hydrophobic polyester chains of molecules, creating a protective hydrophobic film.