Reinforced concrete reinforcement is a variety of elements made of steel, as well as ready-made frames that are placed inside the concrete mass. They are mainly used in places of structures that must be subject to tensile forces. Rebar is the most important part in reinforced concrete. It must reliably serve together with concrete at all stages of the structure's operation. Metal trading companies that sale of reinforcement and rolled metal usually provide a wide range of metal products. To save money, they can use high-strength low-alloy steel, as well as reinforcing steel that has been heat treated and mechanically sealed in advance.
The steel reinforcement is compacted by drawing and twisting. In the case of drawing, the rod is passed through the tapered holes and crimped. For stretching of the reinforcement, forces are applied above the value of the yield strength of the steel. In this case, the armature may lengthen. The best way to strengthen the reinforcement from a technical and economic point of view is to twist it around the longitudinal axis in a cold state. Mechanical compaction changes the structure of the metal, increasing the yield strength of steel by about 30 percent.
Another way is heat treatment. It is done in the following ways:
- high frequency current
- isothermal hardening
This method makes it possible to increase the strength of reinforcement by 30-60 percent for steel 35HG2S, for steel St5, 25G2S and 35GS by 100 percent. The yield strength of steel increases by 65-130 percent and 150 percent, respectively. This saves up to 35 to 40 percent of the reinforcement, respectively.
Steel reinforcement is classified according to the profile of the bar, its application and the manufacturing method. According to the manufacturing method, the rebar is divided into rod and wire cold-rolled. Rod reinforcement is divided into hot-rolled, thermally hardened or drawn. In the latter case, it is cold drawn after rolling. According to the profile of the bar, the reinforcement is subdivided into smooth and periodic profiles.
Wire reinforcement is subdivided into reinforcing wire products and simply reinforcing wire. The latter is divided into 2 types: cold-drawn class Bp-I, it is also called low-carbon, and class Br-P, carbonaceous. Low carbon wire rod is designed for stress-free reinforcement. Carbonaceous is intended for prestressed reinforcement.
