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How does prestressed concrete resist forces that would crack ordinary concrete?

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Cement The cement-making process, from crushing and grinding of raw materials, through roasting of the ground and mixed ingredients, to final cooling and storing of the finished product.

Prestressed concrete resists the tensile forces that typically crack ordinary concrete by placing the material into a state of permanent compression. While ordinary concrete has high compressive strength, it is weak in tension and prone to cracking under bending forces.123

To overcome this, prestressed concrete utilizes steel wires or cables that are stretched to create a "live force" within the structural member. This is achieved through two primary methods:3

Pretensioning: Steel cables are stretched in a mold before the concrete is poured. Once the concrete sets, the cables are released; as they attempt to shrink back to their original length, they compress the surrounding concrete.12
Posttensioning: After the concrete has hardened, steel is run through internal ducts, anchored to the exterior, and then stretched using a mechanical force.12

By pre-compressing the concrete, the material can counteract the tensile bending stresses of an applied load. Essentially, the member acts like a spring, ensuring that no tension is experienced until the initial compressive force is fully overcome. This allows the structure to carry greater loads and span longer distances than ordinary concrete.132