Pre-stressed concrete is the type of concrete in which internal stresses are intentionally induced in a planned manner such that the stresses resulting from the superimposed loads get counteracted to a desired degree.

Pre-stressed concrete is a specialized type of concrete that is used in a wide range of construction applications, including bridges, buildings, and other structures. It is designed to improve the strength and durability of concrete by introducing compressive stresses before the concrete is subjected to loads.

Pre-stressed concrete is achieved through the use of high-strength steel reinforcement, often in the form of tensioned steel cables or bars, which are placed within the concrete before it is cast. These steel reinforcements are tensioned, or pre-stressed, to a predetermined level using hydraulic jacks. Once the concrete has hardened and gained sufficient strength, the jacks are released, allowing the steel to transfer its pre-stress to the concrete.

The pre-stressing of the concrete creates internal compressive stresses, which counteract the tensile stresses that are induced when the structure is subjected to external loads. This provides several advantages over traditional reinforced concrete:

1. Increased Load-Carrying Capacity: Pre-stressed concrete can carry larger loads and span greater distances than traditional reinforced concrete. The pre-stressing effectively reduces the tensile stresses that would be present in the concrete under load, allowing the structure to support heavier loads without failure.

2. Crack Control: The pre-stressing of the concrete helps to control cracking, as the compressive stresses counteract the tensile stresses that would normally cause cracking. This improves the durability and longevity of the structure.

3. Flexibility in Design: Pre-stressed concrete allows for more flexibility in design, as the pre-stressing can be tailored to meet specific design requirements. This allows for the creation of complex and innovative structures that would not be possible with traditional reinforced concrete.

In conclusion, pre-stressed concrete is a type of concrete in which internal stresses are intentionally induced to counteract the stresses resulting from superimposed loads. It offers increased load-carrying capacity, crack control, and flexibility in design, making it a preferred choice for a wide range of construction applications.