FERROCONCRETE. Ferro-concrete or reinforced con crete is a combination of fine concrete with embedded steel bars adapted to structural purposes. The concrete element is an arti ficial stone-like material of excellent durability which offers great resistance to crushing or compressive stress, but has relatively small tensile strength. Mild steel bars, on the other hand, have great tensile strength and when provided in suitable quantity and correct location can be utilized to make good the deficiency of the concrete in that respect. Construction in ferro-concrete is there fore based on the combination of the two materials according to scientific principles whereby they co-operate in sustaining safely the loads and stresses to which the structure is exposed.
The first operation in the execution of a ferro-concrete struc ture consists in the forming and supporting in correct position of a set of external moulds of timber or sheet metal which repro duce the form of the members or parts to be constructed. The next step is the placing and fixing of the system of steel reinforc ing bars within or on the moulds, which are then filled with soft concrete newly mixed. The steel reinforcement thus becomes em bedded in the concrete which gradually hardens and forms the general binding material of the system. After the lapse of a set ting period of a few days or weeks the moulds are removed and the finished concrete is exposed. Such construction is adapted to an infinite variety of purposes in engineering and building con struction and is now preferred for many purposes for which wood and steel were formerly considered appropriate. It has great ad vantages over wood in respect of strength and durability and is much superior in fire-resisting qualities to both wood and bare steelwork. In most circumstances, too, the steel bars in ferro concrete are efficiently protected by the cement against corrosion. See CONCRETE. (J. WI.)