Why is reinforcing steel (rebar) used in concrete?

Reinforcing steel, commonly referred to as rebar, is incorporated into concrete structures primarily to improve their tensile and flexural strength. Concrete is excellent in compression but weak in tension; it can easily crack when subjected to forces that cause tension. By embedding rebar in the concrete, engineers are able to address this limitation.

The rebar provides additional tensile strength, allowing the concrete to withstand bending forces (flexure) and stretching forces (tension) without cracking. This combination results in a composite material that is significantly stronger and more durable than concrete alone. The use of rebar is crucial in applications such as beams, slabs, and columns where enhanced structural integrity is necessary to support loads and resist bending or breaking under stress.

The other options do not accurately capture the primary purpose of rebar in concrete. Reducing weight is not a characteristic of adding rebar, as it increases the overall weight of the structure. Curing time is related to the hydration process of the concrete mix and does not change with the presence of rebar. Aesthetics may be a consideration in design but do not relate to the fundamental structural benefits that rebar provides.