Concrete is the most widely used building material. Steel is often used to increase the strength of the concrete. Under pressure load, reinforced concrete performance, under tensile load, but it has the drawbacks of brittle. Concrete curing tensile stress leads to the crack, crack will allow water to enter, which causes corrosion.
Fibre-reinforced plastics (FRP) long ago was thought to be a way to improve the performance of concrete materials. United States concrete Institute (ACD for short) and the Japan Society of civil engineers and other groups has been committed to the development of FRP reinforcement-specifications and test methods, many of which have been applied in the concrete structure. In 1990, the ACI 440 Committee was set up, designed for engineers and design staff provides information and guidance on FRP reinforcement.
FRP reinforcement, glass fiber reinforced plastic bars (hereinafter referred to as glass and steel) was developed earlier, is now relatively mature technologies. Over the past more than 10 years, glass and steel from the sample into a practical product, has been effectively in place of steel in many projects. Especially with the rising price of steel, its growing application. United States well-known reinforcement manufacturer Hughes Brothers company, glass and steel are used, this is a very competitive market, industry awareness of this reinforcement is much stronger than before.
Due to the corrosion of glass and steel, it is particularly suitable for needs salt, antifreeze concrete structures, offshore concrete structures and underground engineering. For some special facilities, such as magnetic resonance imaging in hospital room or using radio frequency technology to identify a pre-paid toll station channel, FRP tendons are the best choice. In these places do not use steel because steel interference electromagnetic signals, and glass and steel with excellent electromagnetic wave permeability. In addition, the glass and steel light weight (about reinforcement of 1/4) and insulation also makes it popular.
Glass and steel is usually made with e-glass fibers and vinyl ester resins. Also use instances of ECR glass fibers. According to another report, France glass manufacturer Saint-Gobain company uses its arcotex alkali-resistant glass fiber glass reinforced, high chloride and alkali environment shows excellent resistance to corrosion. The basic resin glass and steel, except for vinyl ester, a polyester, epoxy and phenolic resin.
Glass reinforced pultrusion molding is often used. Mainly longitudinal reinforced. Fiber volume content of 50%~65%. In North America, the diameters of the glass and steel 6mm~32mm (#2~#10 bar).
Due to the different mechanical properties of FRP and steel, ACI specifically developed a guidance document, the FRP bars reinforced concrete design and construction guidelines. This guide focuses on the FRP rebars in concrete cutting, bending, creep, and fatigue, and usability. Although glass and steel could not bend at the construction site to accommodate unforeseen circumstances, but manufacturers say that's not a problem. Epoxy resin coated steel bar cannot be bent, bent will make the coating damage. Glass and steel at the time of manufacture in accordance with the engineering design of the Prebend. Methods of test for FRP bars reinforced concrete was released, owner and designer of this concrete performance is assured.