Rebar

Rebar is steel reinforcement embedded in concrete to help it resist tension. Its bond with concrete lets both materials act together under load.

Reinforced concrete: Composite construction material in which concrete and embedded reinforcement work together to carry loads. Rebar supplies tensile capacity to this composite while concrete carries much of the compression.
Concrete: A composite material made from cement, water, and aggregates that hardens into a stone-like mass. Concrete’s low tensile strength is the reason embedded steel reinforcement is needed.
Reinforced concrete beam: A concrete structural member designed primarily to resist bending and shear. Longitudinal rebar resists tensile bending stresses, while stirrups commonly resist shear.
Prestressed concrete: Concrete in which tensioned tendons introduce compression to counteract service-load tensile stresses. Unlike ordinary rebar reinforcement, prestressing actively compresses concrete before service loads act.
Reinforcement corrosion: The deterioration of steel reinforcement through electrochemical reactions in concrete. Corroding rebar expands, cracks surrounding concrete, and can reduce structural capacity.
Bond (mechanics): The transfer of force across the interface between two materials in contact. Bond transfers stress between concrete and rebar so they deform together.
Structural steel: Steel made and specified for load-bearing construction components. Rebar is a specialized structural steel product shaped for embedment in concrete.
Reinforced concrete column: A vertical concrete structural member that carries axial force, often with bending. Longitudinal bars and transverse ties help columns carry loads and restrain buckling.
Post-tensioned concrete: Concrete construction in which tendons are tensioned after the concrete has hardened. Post-tensioning uses stressed tendons rather than relying only on passive rebar.
Carbonation (concrete): A reaction in which atmospheric carbon dioxide lowers the alkalinity of concrete. Carbonation can remove the alkaline protection that normally limits rebar corrosion.

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