Prestressed Concrete Types

There are two types of prestressed concrete based on the construction method:

I. Prestressed Concrete 

II. Post-tensioned concrete that is bonded. 

III. Post-tensioned concrete without bonding

Concrete that is pre-tensioned

This process involves first tensioning wires or tendons, and then pouring concrete. It improves the bonding strength between the concrete and tendon. Tensions are passed directly and the tendons are shielded from corrosion as a result. When the concrete hardens, the tension in the anchored and stretched tendon is transferred to the material. The tendon then attempts to return to its initial length, but the concrete's bond resists it; as a result, compressive force is induced in it.

Concrete with Bonded Post-tensioning

Comparable to pre-stressing, except that tendons are tensioned after concrete is poured. After the member's tendon is positioned appropriately, casting is completed. The tendons are tensioned against the concrete by hydraulic jacks once the concrete hardens. Tendons are set in place when they are suitably tensioned in accordance with design. Tension continues when the jacks are removed, applying pressure to the concrete. This technique is frequently employed to make monolithic slabs for large-scale home building projects, where problems with expanding soil can occasionally arise. In addition, post-tensioned concrete is utilized in bridge construction.

Post-tensioned Concrete Without Bond

Compared to bonded post-tensioned concrete, it differs slightly. It permits unrestricted cable movement. Each tendon is encased in plastic and lubricated for this purpose. Through anchors, the cables distribute stress to the concrete. This has several benefits, such as: a. The capacity to strain tendons before attempting repairs.

b. The capability to modify cables separately

There are also drawbacks, such as the possibility of one or more cables distressing themselves and bursting out of the slab in the event of damage.  

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