Why is concrete strong in compression but weak in tension?

Concrete is an artificial stone, and like natural stone, it possesses high compressive strength but is inherently weak in tension.1

Its strength in compression arises from its composition as a dense, hard material capable of resisting crushing forces. However, because it is a brittle material, it does not easily withstand tensile or bending stresses caused by forces such as wind, vibrations, or earthquakes. Without reinforcement, these tensile stresses can cause the material to rupture.234

To overcome this limitation in engineering, builders use reinforced concrete, which embeds steel rods or mesh within the concrete. The steel provides the necessary tensile strength that the concrete lacks, allowing the combined structure to sustain heavy loads over large spans. Another method, prestressed concrete, uses tensioned steel cables to place the concrete under permanent compression, effectively neutralizing the tensile forces that would otherwise cause the material to crack.214