Concrete is essentially a simulacrum of stone: it is derived from it and is similar in appearance, composition, and properties. Concrete reinforced with steel is fundamentally different: there is no naturally occurring material like it. When concrete reinforced with steel comes under bending stresses, the inner skeleton of steel soaks up the stress and protects it from the formation of large cracks. It is two materials in one, and it transforms concrete from a specialist material to the most multipurpose building material of all time.
