Changes of concrete alkaline state would destroy the steel surface of the passive film, then there reinforcement the localized corrosion. Corrosion of reinforcement is reinforced concrete structure damage and one of the main causes of early failure. With domestic steel corrosion in concrete structures, which lead to a decrease in durability due to more and more problems, a variety of new anti-corrosion technology become a research hotspot. Coating technique is a simple and effective anti-corrosion measures.
Causing failure of reinforced concrete is many reasons, resulting in deterioration of concrete reasons for failure were steel corrosion, freezing and thawing, alkali – aggregate reaction and sulfate attack and so on. Swelling and cracking in the concrete deterioration plays a decisive role. Because hydration steel surface passivation film formed alkaline, complete passivation film plays a continuous protective effect. Concrete is a porous material, giving the surface coating to isolate or limit its contact with aggressive media and the occurrence of alkali- aggregate reaction, which can improve the durability of concrete and the steel in concrete from corrosion, in addition to decoration and beautifying effect. Overbased for concrete, water and porosity characteristics, the coating should have alkali resistance, water resistance, weather resistance and good impregnating properties. A rigid outer coating of concrete surface coatings ( such as cement -based capillary crystalline coating, polymer cement mortar coating ) with a flexible coating ( such as silane coated with acrylic resin coating ) two species, can be to some extent, prevent water and aggressive media in contact with concrete, durability of concrete protection plays a positive role in promoting.
Currently the new coating material durability of concrete structures can be divided into multi-function spray polyurea, penetrating protective solution ( water repellent, water repellent ) and fiber type of protection increased material From the principle analysis, polyurea and fiber reinforced concrete surface protection materials can be formed in high flexibility, high intensity continuous protective layer, thereby serve to prevent structural cracking, corrosion and enhance the role of structural durability; while only permeable protective solution form a dense protective layer can not be improved brittleness of concrete, it is difficult to prevent cracking of the structure. From the construction of technical analysis, polyurea technology using special spraying equipment construction, increase efficiency than fiber-type protective material has greatly improved.
Epoxy coating does not react with the acid, with a high chemical stability, as well as dry out, the characteristics of large ductility, with the metal surface has excellent adhesion. While effectively isolate the steel surface, cutting chloride ion channel, is produced on the surface of the metal film is an ideal material for corrosion. However, the use of coated steel and concrete will also cause some bonding properties adversely affected by increasing the thickness of the protective layer, appropriate to extend the length of anchoring and binding measures to be addressed. Reinforced concrete structures in multi- threaded rebar corrosion epoxy coating. Epoxy resin and liquid epoxy resins in powder two, the main raw materials include epoxy resins, plasticizers, curing agents and alkali materials. A liquid epoxy resin paint coating method, spray coating method and the dipping method epoxy powder electrostatic spray coating method, powder electrostatic powder bath and bath. Electrostatic spraying method is first heated steel and then sprayed on the steel surface liquid epoxy, epoxy when heated to melt the plastic will increase a lot, will solidify after cooling, the steel surface to form a dense continuous coating. Powder coating is based on the principle of electrostatic induction of the question, the gun and the workpiece to form the electrostatic field , the powder in the dual role of static electricity and compressed air uniformly adsorbed onto the workpiece.
Post time: Sep-11-2019