Steel Reinforcement

Since, concrete is relatively weak in tension, reinforcement

consisting of steel bars, strands or wires is required to absorb

tensile, shearing and sometimes the compressive stresses

in a concrete member or structure. Steel reinforcement is

also required to tie vertical and horizontal elements, reinforce

the edges around openings, minimize shrinkage cracking and

control thermal expansion and contraction. All reinforcement

should be designed by a suitably qualified engineer.

      Reinforcing bars are steel sections hot-rolled with ribs

or other deformations for better mechanical bonding

to concrete. The bar number refers to its diameter in

millimeters – for example, a 6 bar is 6 mm in diameter.

     The welded-wire fabric consists of a grid of steel wires or bars welded together at all points of intersection. The fabric

is designated by the size of the grid in mm followed by a number indicating the wire size.

     Reinforcing steel must be protected by the

surrounding concrete against corrosion and fire.

Minimum requirements for cover and spacing

are specified by the by-laws. Design of Concrete

Structures according to the concrete’s exposure

and the size of the coarse aggregate and steel

used.