Reinforced Cement Concrete (RCC) is concrete with steel reinforcement bars (rebar) embedded in it. Plain concrete is strong in compression but weak in tension — it cracks easily when bent or stretched. Steel is excellent in tension, so combining the two produces a composite that handles both: the concrete carries compression, the steel carries tension.
This is why almost every structural element in a modern house — slabs, beams, columns, footings, lintels — is made of RCC rather than plain concrete. The steel is positioned where tensile stresses occur (for example, the bottom of a simply-supported beam), and the concrete around it also protects the steel from corrosion and fire.
RCC design balances the concrete grade, the amount and placement of steel, and the cover (the concrete thickness over the bars). Estimating an RCC element means calculating both the concrete volume and the steel weight — the latter from a bar bending schedule using the d²/162 unit-weight rule.