Steel, the most versatile, strong and durable material for reinforcing concrete for constructing buildings. No doubt, it is the only material so far that has proven successful to bond with concrete for reinforcement. The main reasons are, One, steel has high tensile strength and is able to withstand the tensile forces in a structure which the concrete lacks. Second, the thermal coefficient of expansion of steel is similar to that of concrete.
The construction of a building is virtually incomplete without reinforcement. In construction, Steel is the primary alloy used for reinforcement. There is a reason for that because as we know that concrete is used for the construction of the building, even though it provides the compressive strength, it has weak tensile strength for withstanding induced forces. Therefore by combining reinforced bars, it provides the tensile strength for concrete to withstand induced forces. Also, The properties of thermal expansion for both steel and concrete are approximately the same which is why steel is used as reinforcement.