Improving the strength characteristics of foundations and concrete wall panels is impossible without the use of high-quality reinforcing bars - steel rods or wire, which are laid in the concrete mass before it sets. The correct choice of reinforcement profile is the key to ensuring the durability of buildings. Unfortunately, or fortunately, rolled metal in modern construction is indispensable.
Classification of types of building reinforcement
In accordance with the norms provided for by the current GOST 10922, steel reinforcing bars are distinguished by the following parameters:
- According to the assortment of cross-section - smooth round, with ribbed notches along a helical line, with transverse protrusions of the “herringbone” type.
- According to the grades of used steels - ordinary quality GOST 380, high-quality structural GOST 1050, construction steels GOST 5058, structural alloyed GOST 4543.
- As of delivery - hot or cold rolled steel.
- By the length and dimensions of the cross-section of the original blanks - rods or wire.
Smooth steel reinforcement made from steels of ordinary quality (steel grade St.3kp is more often used) is used at low loads on the bases. Such fittings can withstand pressures of no more than 160 ... 180 MPa, and belong to class A-I.
Armature of class A-II is accepted at a design level of permissible pressures of 240 ... 250 MPa. It is made from steel St.5, or (with a complex and uneven distribution of operating loads) from steels of grades 10GT, 12GS, 18G2S.
Class A-III fittings are used in the construction of multi-storey buildings. It is made of low-alloy steels of grades 25G2S or 30GS.
In especially difficult operating conditions (multi-storey buildings with possible vibration loads), the use of class A-IV fittings is provided. For its production, structural steels are used, which include chromium, for example, 30HG2S.
How to decide on the range of building reinforcement
Based on the optimal cross-sectional dimensions (up to 12 mm in diameter - a bar or wire, after 12 mm - only a bar), a bar profile is predominantly used. With alligator or manual reinforcing scissors, it is pre-cut into measuring rods. However, if the foundation has an increased width, it is advisable to provide a twisted wire in accordance with GOST 2591. A reinforcing mesh is formed from such wire, the edges of which are welded together.
To select building fittings, take into account:
- Reinforcement class. On the
