The penetration of moisture into the capillary-porous structure of concrete leads to the development of corrosion processes, the formation of efflorescence, the decrease in strength and the subsequent destruction of the cement-sand composite. At the same time, the increased humidity of the structure is a favorable environment for the development of various biological damages (mold, fungi, lichens), which, in turn, leads to both decrease in the operational characteristics of the structure and loss of the aesthetic appearance of the building facade. In this regard, the study of possibility of increasing the waterproofing of concrete by compaction of its structure is of great interest. The paper discusses the effect of penetrating additives on the physicomechanical characteristics of fine-grained concrete and fiber-reinforced concrete. It has been established that the introduction of a penetrating additive into the composition of cement-sand composites leads to the filling of the capillary-porous structure of materials with needle-like new formations, which makes it possible to increase their resistance to moisture influence, namely, to increase the waterproof grade, reduce the depth of water penetration into the concrete structure, increase the contact angle of wetting the surface of the material. It was also noted that the simultaneous introduction of a penetrating additive and fiber into the concrete composition allows not only to increase the waterproofness of the composite, but also to improve hydrophobic performance by imparting a hierarchical surface structure to the material.

The existing methods of confering hydrophobic properties to various building materials are considered. Obtaining special, including hydrophobic, properties of water-emulsion paints is a very relevant task. Previously, a method was developed for producing an emulsion of a polysiloxane stabilized with polyvinyl alcohol. The paper describes the possibility of using a hydrophobisating emulsion of polyhydrosiloxane as a functional additive for an acrylic water-dispersion paint. This emulsion is capable of forming coatings on dense and porous surfaces with an adjustable contact angle up to 105 °. The use of this emulsion, with its sufficient coalescence for volumetric hydrophobization of coatings, makes it possible to obtain a high contact angle on the surface. In the paper, it was assumed that the partial introduction of small amounts (up to 10 %) of a hydrophobizing emulsion into water-dispersion paints would allow achieving the contact angle of wetting for similar coatings consisting exclusively of emulsion. It is shown that the introduction of small amounts of a hydrophobizing emulsion with an auxiliary coalescing action of ethylene glycol makes it possible to impart hydrophobic properties to the surface of the resulting coating. When the optimum concentration of ethylene glycol in the coating is reached, dissolution and transport (yield) of polysiloxane to the surface is ensured. The research carried out made it possible to develop a paint composition with a hydrophobizing emulsion with a contact wetting angle of about 100 °, which ensured the hydrophobicity of the previously hydrophilic coating of a water-dispersion acrylic paint.