Value in terms of application
In today's rapid economic and social development, reinforced concrete structure buildings have long been all over all aspects of our production and life, with the continuous development of reinforced concrete structure technology, coupled with the need for energy conservation and emission reduction and sustainable development, building safety and environmental protection has become an important reference for design and construction. However, due to the influence of concrete carbonization, chloride erosion and other factors, the rust of steel bars in concrete seriously affects the safety and service life of the structure, in order to change this phenomenon, epoxy coated steel bars have been more widely used.
Epoxy coated rebar is a kind of coated rebar produced by using electrostatic spraying method under factory production conditions, and the melt combined epoxy coating is sprayed in powder form on the surface of ordinary ribbed rebar and ordinary optical circular rebar. After curing, a complete, continuous, epoxy film protective layer covering the entire surface of the steel bar is formed, and the protective coating contains thermoset epoxy resin, curing agent, pigment and other additives.
Epoxy coated steel bars have good corrosion resistance and are suitable for reinforced concrete structures in industrial and civil houses, roads, bridges, offshore buildings, garages, sewage treatment tanks, ports, docks and general structures in humid environments or aggressive media.
Strict quality control is key
Compared with ordinary steel bars, the quality control of epoxy coated steel bars involves more aspects, not only the quality of the steel bars themselves must meet the requirements of relevant standards and specifications, but also the quality of the epoxy powder used and the finished coating quality is a control link that cannot be ignored. Due to the presence of the reinforcement coating, the bonding strength of the concrete is significantly reduced, and if the coating cannot play its due role, the role of epoxy coated steel reinforcement will not be able to talk about.
According to relevant tests and engineering practices, if the coating of epoxy coated steel bars is incomplete, there are defects such as holes, punctures or too thin film layers, in the corrosive environment, the steel bars in the structure will still rust, especially in the damaged coating, and the development of local rust is often faster than that of uncoated steel bars, so it is necessary to strengthen the inspection and testing of epoxy coated steel bars to ensure the quality of its products.
In addition to not having holes, voids, cracks and other visually visible defects, but also to ensure the thickness of the coating, some products although the coating continuity and integrity of no problems, but the coating thickness is insufficient, applied to the actual engineering project, will still lead to a lot of quality problems.
According to the requirements of the relevant specifications, the recorded value of the cured coating thickness should be at least 95% more than 180μm ~ 300μm, and the single record value should not be less than 140μm. Moreover, for different use environments, its thickness requirements are also different. In environments with high requirements such as corrosion resistance, the recorded value of the cured coating thickness should be at least 95% more than 220μm~400μm, and the single recording value should not be less than 180μm. It can be seen that the coating thickness is a very important technical indicator of epoxy coated steel reinforcement, and it also has a more direct impact on its corrosion resistance.
The specific testing items and technical requirements of epoxy coated steel reinforcement should also fully consider the structural characteristics of reinforced concrete, and ensure that the technical indicators of bendability, coating adhesion and bond strength of epoxy coated steel reinforcement coating meet the requirements, so as to achieve the safety and stability of the overall structure and truly play the advantages of epoxy coated steel reinforcement.
Pay attention to the patching process
The requirements for epoxy coated rebar, although strict, do not allow the presence of any flaws. For the coating damage that is visually visible within the allowable range, a certain method can be used to repair according to the instructions for use of the repair material, but the choice of materials used for repair must be cautious, and the repair material should be compatible with the molten combined epoxy coating and have inertia in concrete. Chemical resistance should also be used to detect and evaluate the foaming resistance and corrosion resistance of the repair material under exposure to the atmospheric environment, and the salt spray test should be used to evaluate the resistance of the repair material to corrosion in the humid and hot environment.
In order to ensure the quality of repair, before the coating repair, all the rust in the damaged part should also be removed by appropriate methods, so that the repair quality can meet the relevant technical requirements, and when repairing the damage of the coating, it is necessary to pay attention not to apply too much of the repair material to the intact coating.
Due to the different sizes of reinforced concrete structures, if the epoxy coated steel bars are cut, the cutting site should be sealed with the same repair material, and the quality control of production, transportation, storage and use should be done.