With the development of modern construction and industry, reinforced concrete structures are widely used in infrastructure and construction projects. However, these structures are often exposed to corrosion and deterioration caused by environmental factors during long-term service, especially in humid and chemically contaminated environments. Therefore, in order to prolong the service life of reinforced concrete structures, the application of corrosion-resistant coating has become an important means of protection. Corrosion-resistant coatings not only insulate from corrosive media, but also improve the compression, weatherability and overall service life of the structure.
Requirements for corrosion-resistant coatings for reinforced concrete
Corrosion-resistant coatings for reinforced concrete face multiple challenges in preparation and use, including alkali resistance, water resistance, air permeability, etc. The following are the requirements for corrosion-resistant coatings under different surface conditions:
Wet concrete surface coating requirements
Alkaline resistance needs to be considered when coating wet concrete surfaces, as alkaline salts form during the hydration curing process of concrete. If the coating material is not alkaline resistant, it will cause it to decompose and fall off in an alkaline environment. Therefore, the selection of polymers and pigments with excellent alkali resistance is the key to coating materials. For example, chlorinated rubber and vinyl resins are commonly used alkali-resistant polymers, while pigments such as titanium dioxide and chromium oxide have good alkali resistance.
Dry concrete surface coating requirements
In dry environments, the alkali resistance, adhesion and wettability of corrosion-resistant coatings are particularly important. Latex paints, chlorinated rubbers, vinyl coatings, epoxy coatings, polyurethane coatings, etc., can be applied to dry concrete surfaces. For applications with high environmental corrosion conditions, a multi-layer coating system is often chosen to improve the durability and corrosion resistance of the coating.
Applications and properties of various types of corrosion-resistant coatings
According to different use needs and environmental conditions, the application characteristics of different types of coatings in concrete structures are as follows:
Latex paint coating
Latex paint is widely used for surface decoration and protection of concrete, and its main feature is that it has good air permeability and decoration. Commonly used types of latex paints include acrylic latex, styrene and acetacrylic latex paints, which are suitable for concrete surfaces that have been sufficiently dried but may have a small amount of moisture left inside.
Chlorinated rubber coatings
Chlorinated rubber coatings have excellent alkali resistance and adhesion, and form a good protective coating on wet or dry concrete surfaces. The disadvantage is poor air permeability and is generally not suitable for concrete surfaces with high water content. The aging resistance and toughness of the coating can be further enhanced by adding plasticizers and using inert pigments.
Vinyl paints
Vinyl coatings have similar properties to chlorinated rubber coatings and have good durability, but are slightly inferior in terms of water and chemical resistance. Vinyl coatings are often suitable for application to cement substrate surfaces, which can improve the weatherability and chemical resistance of the surface to a certain extent.
Epoxy coatings
Epoxy coatings are widely used for the protection of reinforced concrete structures due to their strong adhesion, water resistance, and chemical resistance. Especially in steel-concrete structures in steel companies and chemical plants, epoxy coatings can form a high-strength protective layer to reduce the corrosion of the structure by chemicals such as acids, alkalis, and salts.
Corrosion characteristics and corrosion resistance measures of steel-concrete structures
In chemical, steel and water conservancy projects, reinforced concrete structures are often exposed to acid gas, salt particles and high humidity, resulting in accelerated corrosion and damage of the structure. Specific measures include:
Protective measures
The reinforced concrete structures used in chemical enterprises and iron and steel enterprises must have strong adhesion and crack resistance due to the dual effects of vibration and corrosion. For this purpose, epoxy coal asphalt coating, epoxy FRP coating, or spraying chlorosulfonated polyethylene materials are usually used to form a multi-layer protection system to improve its durability.
Protection of water conservancy projects
The reinforced concrete structure of water conservancy projects is affected by factors such as water flow, sediment erosion, and alternating dry and wet all year round. The anti-corrosion thickness can be increased by applying an epoxy high-build anti-corrosion coating, creating a high-thickness coating to resist physical erosion and chemical attack.
summary
Corrosion-resistant coatings on reinforced concrete surfaces play a key role in construction, industrial and hydraulic engineering against moisture, chemical corrosion and oxidation. The use of suitable corrosion-resistant materials in different environments, such as latex paints, chlorinated rubber and epoxy coatings, can enhance the alkali resistance, crack resistance and durability of the coatings, thereby extending the service life of concrete structures. This type of coating technology provides an important guarantee for improving the corrosion resistance of steel-concrete structures.
