Steel Reinforcing Rebar is used in concrete to provide additional strength, as concrete is weak in tension, while steel is strong in both tension and compression. Steel and concrete have similar coefficients of thermal expansion, so a concrete structural member reinforced with steel will experience minimal stress as the temperature changes. Rebar is used in bridges, roads, driveways, buildings, skyscrapers, homes, warehouses, concrete curbs, slabs, foundations and retaining walls to increase the strength of a concrete structure.