Influence of moisture on the durability of protective and decorative coatings of external walls of buildings

Abstract

The article presents the results of a study of the effect of air pressure in the pores of a cement substrate, which occurs when the wall material is moistened, on the crack resistance of protective and decorative coatings. It is shown that the value of air pressure in the pores of the material, provided that the moisture content of the wall material does not exceed the sorption limit, does not pose a threat to the integrity of most coatings. When the moisture content of concrete is higher than the sorption air pressure, it is comparable to the long-term cohesive strength of some protective and decorative coatings (lime, polymer-lime, KhSPE, etc.). When finishing external wall panels with a paint composition based on organic solvents (toluene, xylene, etc.), a saturated vapor-gas mixture is formed in the pores, which helps to reduce the rate of surface condensation. The destruction (peeling, cracking) of coatings from the action of air pressure in the pores of the substrate begins later in comparison with coatings based on aqueous paint formulations.