The fibreglass reinforcement (also called glass-fibre reinforced plastic or composite reinforcement) has replaced conventional reinforcement. It has a rather complicated structure. The basis is a bundle of ultra-strong glass or basalt fibres, which are formed in the reinforcing bar. Synthetic resins are used as a binder for fibres. They perform two functions at once: protect the fibres from mechanical effects and from the harmful effects of the environment during the manufacture of the product and during its operation, as well as ensure their joint work.
The fibreglass reinforcement manufacturing process of consists of several main stages. First, fibreglass in the form of continuous strands is impregnated in a special container with a polymer resin, which contains a curing composition, as a result of which the so-called roving is obtained. Then, when the fibreglass is completely soaked, the roving is fed into the forming die to obtain a bar of a given diameter. Without waiting for the bar to harden, the source material is pulled through the polymerization chamber, heated to a certain temperature. Finally, the stock is wound and secured to create a ribbed surface. The bar with the rib wound onto it enters the drying chamber, where the resin is polymerized. After polymerization, the finished reinforcement enters the cooling unit, and then the reinforcement is cut into sections of a predetermined length or wound into coils.
Two main components are used in the production: reinforcing material itself (roving) and binder (epoxy or polyester resin). The ratio of these components is about 80/20. In the finished reinforcement, the roving perceives mechanical loads, and the resin acts as a matrix, uniformly distributing the load along the entire length of the bar and protecting the reinforcement from the external environment.
There are special requirements imposed on the production facility. Its length shall be at least 50 meters (recommended length is 70 meters), ceiling height shall be at least 2.5 meters (recommended height is at least 3 meters), the height difference in the equipment location area shall be not more than 4-5 cm, ventilation with air outflow of at least 200-250 litres per minute shall be provided. Indoor air temperature shall be at least 16-18 °С.