Reinforced concrete
Reinforced concrete casts steel into concrete so the steel carries the tension the concrete cannot, the basis of footings, slabs, beams and walls under AS 3600.
Ask Chalkline about this →Reinforced concrete is concrete cast around steel reinforcement so the steel carries the tension that concrete cannot. It is the basis of footings, slabs, beams, columns, and walls, designed under AS 3600 (and, for residential slabs and footings, AS 2870).
The principle is that the two materials cover each other’s weakness. Concrete is strong in compression but weak in tension: it cracks and fails when pulled or bent. Steel is strong in tension. By placing steel (reinforcing bar or mesh) where the element is in tension, the steel takes the tension while the concrete takes the compression, and the two bond and act as one. That is why a beam has bottom steel (tension at the bottom under load), a cantilever has top steel, and a slab has mesh.
Three things make reinforced concrete actually work:
- Bar position: steel must sit where the tension is. Top steel walked down to the bottom, or bottom steel sitting on the ground, defeats the design.
- Cover: the concrete cover over the steel protects it from corrosion and fire, and is specified for the exposure. Too little cover and the steel rusts, spalling the concrete.
- Continuity: bars lap and connect (including starter bars between pours) so tension carries across the whole element.
For a builder the practical points are to keep the reinforcement in its designed position on chairs and spacers (cover and position are the most common site failures), to maintain the specified cover top and bottom, to lap and tie bars per the drawings, and to keep it clean and supported during the pour. Reinforced concrete only delivers its design strength if the steel ends up where the engineer drew it.
Also known as: RC, ferro-concrete (loosely), steel-reinforced concrete.
Category: Materials / Concrete.
Related
See also
References
- AS 3600 Concrete structures, Standards Australia (verified 2026-06-04)
Last updated: 2026-06-04. Verified: 2026-06-04. Quarterly review for currency.