What is added to concrete in order to increase tensile strength?

• A. Cement
• B. Water
• C. Gravel
• D. Rebar

Answer: (D)

Concrete handles compression well but resists tension poorly. To boost tensile strength, you introduce reinforcement—most commonly steel bars (rebar)—inside the concrete. The steel has high tensile strength and, when cast with concrete, forms a bonded composite that carries tensile stresses as the structure bends or is loaded in tension. The concrete itself still resists compression, while the rebar takes the tensile forces, effectively improving the overall strength of the member. Cement, water, and gravel are essential parts of the concrete mix for binding, hydration, and dimensional stability, but on their own they do not provide the added tensile capacity that rebar does.