Reinforcement for concrete.
Most concrete structures contain reinforcing steel to carry the tensile forces and control crack development under load, at about 4% by volume of the concrete. In the UK, reinforcement is made from recycled steel.
For further information see Concrete and the Environment
, published in CONCRETE
in September 2001, pp39–46. Copies are available as a free download from the Members Area of the Concrete Society web site.