Гидрофобизирующие антикоррозионные покрытия гипсобетонов на основе кремнийорганических макромолекул


технические науки

Из разнообразных подходов антикоррозионной защиты гипсобетонов наиболее технологичным является гидрофобизирующая обработка кремнийорганическими силоксанами. Установлено, что в результате гидрофобизации гипсового композита строительной конструкции образуется бесшовный защитный композиционный полимерный трехмерный слой толщиной 0,1 мкм-1 мкм.

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The external surfaces of concrete structures during long-term operation are subjected to various types of aggressive influences that cause significant corrosion damage [1]. A rational approach to the protection of lightweight concrete structures, including gypsum composites from wetting with water is hydrophobization with water-repellent composite polymers [2]. The development of new anti-corrosion protective coatings with an optimal set of characteristics that ensure reliable operation of gypsum concrete structures in conditions of high humidity remains an urgent task.

This article is aimed at considering effective trends in enhancing the water-repellent characteristics of the surface of gypsum concrete building structures by water-repellent treatment with organosilicon macromolecules.

Corrosion of concrete composites in gaseous and liquid aggressive environments occurs by a variety of mechanisms and different speeds. To protect aerated concrete, gypsum and reinforced concrete [3] building structures, composite materials are effective, the structures of which are modified with hydrophobizing additives, which allow affecting the microstructural defects of the insulated surface (cracks, micropores, etc.). An effective solution to the problem of increasing the corrosion resistance of coatings is associated with an increase in their crack resistance and water-resistance characteristics, which is ensured by the modification of their microstructure by treatment using hydrophobic organosilicon siloxanes [4].

The technological advantages of anti-corrosion protective coatings of gypsum concrete with hydrophobic additives are most effectively manifested in designs where resistance to dynamic and alternating physical and mechanical deformations, low thermal conductivity, and considerable resistance to chemical aggressive environments with simultaneous exposure to several external factors are important. It should be noted practical methods of using macromolecular compositions for corrosion protection of concrete building structures, for example, polysulfides were used as waterproofing nanocomposites [5]. An important role in the use of water-repellent macromolecules in the construction industry is played by the ability to control their diverse characteristics by selecting the appropriate components and various modifying nanoparticles, as well as by changing the micro- and macrostructure of the binder polymer matrix.

Concrete building composites have a capillary-porous microstructure, on which the stability and operational reliability of oil and gas industry facilities largely depend. Water-repellent macromolecules diffuse into the porous microstructure of gypsum concrete structures and enter into physicochemical interaction with concrete components, as a result of which the strength characteristics, frost resistance, and waterproofing corrosion resistance increase. As a result of supramolecular polymerization of organosilicon macromolecules, hydrophobic films are formed that envelop capillaries, pores and microcracks of concrete surfaces of oil and gas industry building structures, causing the effect of blocking “self-healing”.

Organosilicon aminoorganosilanes Si(OН)33Н6}NH2 are used as adhesion promoters of polymeric binders and fillers of building materials. Due to bifunctional amphilicity, organosilanes form nanolayers 1.5–2 nm thick on the surface of gypsum concrete (fig. 1):

Formation of an anti-corrosion water-repellent organosilicon nanolayer on the surface of building gypsum concrete
Figure 1. Formation of an anti-corrosion water-repellent organosilicon nanolayer on the surface of building gypsum concrete

As anti-corrosion coatings of non-wetting with hydrophobic additives, a special place is occupied by superhydrophobic macromolecules, on which a drop of water rolls off (slides) from the concrete surface of building structures. Such hydrophobic macromolecular coatings are characterized by a number of unique characteristics: water resistance, resistance to biocorrosion, to inorganic and organic pollution, and also provide a sliding fluid flow near the concrete surface of building structures of the oil and gas industry.

As a result of hydrophobization of concrete and gypsum composites of a building structure, a seamless composite polymer three-dimensional layer with a thickness of 0.1 μm-1 μm is formed. For the technological production of water-repellent superhydrophobic surfaces of concrete building structures, the use of organosilicon polydimethylsiloxane (PDMS) is innovative [6]. On the surface of the anticorrosion coating with hydrophobizing additives — nanotextured polydimethylsiloxane, the contact angle of the water drop reaches 175°.

Also, for hydrophobic treatment of the surface layer of gypsum concrete, it is promising to use cyclic organosilicon compositions (HRSiO)n. as water-repellent hydrophobic [7]. Water-repellent organosilicon macromolecules of hydrophobizing additives are firmly bound to the surfaces of various concrete structures, glass, ceramics, etc. High stability of hydrophobic coatings indicates the possibility of physico-chemical adhesion between the polyorganosiloxane film and the hydrophilic surface of concrete composites.

To date, practical applications have been developed to increase the durability and stability of water-repellent polymer binders in building composites to enhance operational reliability in aggressive conditions. With the help of such protective impregnation of gypsum concrete, reliable waterproofing from the external influence of water can be effectively performed. For example, water-repellent organosilicon treatment increases the strength of concrete by 25%, increases the frost resistance of concrete structures of oil and gas facilities by 50 cycles (more than F300), and increases water resistance by 3.5 times (to W12 and above).

Modifying regulation of water resistance of gypsum nano-binders to increase the durability of gypsum concrete building structures is considered promising in 3-D additive technologies [8]. The directed supramolecular polymerization of organosilicon oligomers of a siloxane emulsion [9] with the formation of hydrophobic films that envelop micropores and microcracks of gypsum concrete surfaces is correctly interpreted by fractal analysis.

Thus, anticorrosion treatment with organosilicon macromolecules of the surface layer of structures helps to reduce water and gas permeability, increase corrosion resistance, and provides waterproofing of gypsum concrete composites.

Список литературы

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