ABSTRACT
Constructions of concrete and steel, in which the materials are so disposed as to bring into action the highest stress-resisting properties of each, are known as reinforced concrete, sometimes as ferro-concrete or armoured concrete. The ad vantages of this method of construction consists in its great measure of lire-resistance, as instanced by several examples where structures of this character have resisted fierce fires with little injury ; its economy in construction. The adhesive value of the concrete to the steel varies from 250 to 570 lbs. per inch ; the value for properly prepared concrete on a clean steel bar covered with a Portland cement wash may be taken as 500 lbs. per square inch. The value of reinforced concrete depends entirely upon the prudent selection and careful mixing and disposition of the concrete. The best aggregates are shingle or broken sandstone—limestone must be rigorously excluded on account of its change under the action of heat.
