The epoxy coating is the best protective layer for reinforced concrete

China Paint Online News
the main reason for the corrosion damage of reinforced concrete is that the concrete lost its passivation protection effect on the rebar, making the rebar oxidized and rusty, the volume expanded by 3 to 5 times, so that the concrete cracked, accelerated the corrosion of the rebar, so that the concrete structure was destroyed, and eventually led to the collapse of concrete structures and pipes.CO2, CO32-, HCO3-infiltration into concrete in water and soil, so that concrete carbonization, loss of alkaline passivation protection of rebar, water and soil CL-, SO42-plasma penetration into the surface of rebar, accelerate the corrosion of rebar.in coastal areas, water and soil CL-, SO42-CO32- and other harmful chemicals are very large, reinforced concrete bridges, pipe damage is the main cause. Organic coatings such as epoxy, polyurethane, rubber oxide, acrylic, etc. can prevent the penetration of these ions.In foreign countries, through polyurethane, epoxy resin, acrylic, silicone, fluoroethylene, unsaturated polyester and other synthetic resins made of coatings on the concrete layer has been systematic penetration test, water vapor absorption test, concrete carbonization test, the best result is epoxy coating, it has a certain penetration capacity on the concrete, can penetrate into the concrete interior, form a coating can reduce the absorption of water vapor, and slow down the carbonation reaction.epoxy resin coating is highly alkaline and can be attached to alkaline concrete surfaces for long periods of time without soaping and other reactions. Langfang Donghua anti-corrosion company has painted epoxy coal asphalt paint on concrete test blocks, soaked in saturated salt water, has been 26 years, still bright, firmly bonded, the coating as hard as before (see photo 1). And alkyd paint, petroleum asphalt paint in the alkaline effect of concrete will be white, the appearance of saponification, coating off, loss of corrosion, waterproofing effect.university in the United Kingdom measured epoxy-painted concrete, its penetration coefficient of O2, CO2 fell to less than 1% of unpainted epoxy-painted concrete. The effect of chloride penetration is also very good, epoxy coating antichloride permeability is equivalent to a thickness of 134 cm of concrete layer.Ministry of Communications JTJ275-2000 "Harbour Engineering Concrete Structure Corrosion Prevention Technical Specification" Article 7.1.2 stipulates the paint quality and coating performance should meet the requirements, including: anti-corrosion coatings should have good alkaline, attachment and corrosion resistance, the underlying coating should have good permeability, surface coatings should be resistant to aging, coating should be resistant to wear, impact and other properties.with the progress of science and technology, concrete-specific coatings have appeared, which can be divided into bottom coatings and surface coatings. Performance has a division of labor, so that anti-corrosion, waterproof layer more scientific, systematic, complete.(1) the bottomthe bottom coating must have three major characteristics, 1, good alkaline resistance. Newly poured concrete is very alkaline, PH value of more than 13, only epoxy paint can withstand its alkalinity.2, strong penetration ability. It can penetrate the inside of concrete up to 3 to 5mm, close the cracks and pores of concrete, form a special protective layer, can effectively prevent the entry of corrosive media, protect reinforced concrete.3, high bonding force and mechanical strength. With the concrete and surface coating have a good affinity, play a role in carrying up and down.Eastern Chemical Company's GH606 concrete special primer is a permeable coating, the use of low-molecular epoxy resin and low molecular weight curing agent, the paint does not contain any fillers, penetration is very strong, after painting will soon penetrate into the concrete interior, filling cracks, pores, so that loose concrete surface enhancement, into a solid foundation.(ii) surface coating 1, GH101-104 epoxy ceramic coatingepoxy ceramic coating (Ceramic EpoxyCoating) is a liquid epoxy coating (LiquidEpoxyCoating), a new anti-corrosion coating that has been widely used in developed countries, is patented by Donghua Anti-corrosion Company (Chinese patent number ZL02155418.8).Eastern Chemical Company epoxy ceramics for a series of products, including solvent-free GH101 type black epoxy ceramic coating and GH102 type white epoxy ceramic coating, the former coal-containing asphalt is called black pottery, mainly used in contact with sewage and water occasions, the latter does not contain coal asphalt, titanium white powder, called white pottery, is non-toxic, approved by the Ministry of Health can be used in contact with drinking water occasions. GH102 white epoxy ceramic coatings can also be added to pigments can also be made into colored epoxy ceramic coatings for applying the colored requirements of epoxy flooring, concrete pools, grooves, ditches, structures and the inside and outside surfaces of concrete pipes. Construction of solvent-free epoxy ceramic coatings should be developed with Donghua company's two-component special sprayer mechanical spraying construction.East Chemical Company epoxy ceramic GH103 and GH104 is a thick slurry-type coating, suitable for spraying or manual brushing construction, a coating can be applied with a thickness of more than 100 m, normal temperature and self-drying, many applications can get a thickness of 0.4 to 0.8mm coating. Epoxy ceramic coating dense and tough, wear-resistant, water-resistant, chemical-resistant medium corrosion and electrical insulation are very good, good corrosion resistance, because of a large number of high-purity quartz powder, has a unique wear resistance, suitable for the transport of liquid pipes containing sediment. The coating surface is smooth, the coefficient of grinding resistance is lower than that of cast iron pipe, which can increase the transmission volume or reduce the pipe diameter and save electricity. White epoxy ceramic coatings have been approved by the Ministry of Health for domestic licensing of products related to drinking water hygiene and safety (Wei Shui word 2006 No. 0026), approved for use in drinking water. 2, GH202 type thick slurry-type epoxy coal asphalt paint epoxy coal asphalt paint is an excellent concrete surface waterproof, anti-corrosion paint, paint contains the best water resistance of coal coking asphalt, coal asphalt absorption rate is low, anti-microorganisms, resistant to plant root puncture. Epoxy resin bonding force is large, mechanical strength is high, can be at room temperature construction. Epoxy coal asphalt coating is a low-cost, high-efficiency waterproof, anti-corrosion coating, used in concrete and steel anti-corrosion at home and abroad for nearly 60 years of history, enduring. East Chemical Company is the earliest and longest-term production of epoxy coal asphalt anti-corrosion paint production enterprises, the company's general manager Zhang Refining the first to obtain China's epoxy coal asphalt patent (patent number: ZL93221420.7). Now the Company produced a total of five types of epoxy coal asphalt: two solvent-free, no benzene organic solvents in the coating, solid content of more than 98%, can be brushed and mechanized spraying, coating dense, no pinholes, added coagulant can be sprayed up to 300 microns at a time without hanging; Two thick slurry types, the solid content of the coating as high as 85%, can be manual and mechanical spraying; A solvent-based, less viscosity, easy to paint construction. China Resources Power this sea water access project using PCP pipes, the transport of seawater, buried in the beach, especially salt farms and shrimp farms. The anti-corrosion in the tube should choose the epoxy ceramic lining, the minimum thickness of 500 m, the anti-corrosion outside the tube should choose the solvent-free epoxy coal asphalt coating, the thickness should be >800 m.
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