Bonded Post-Tensioning Slab System consists of fully encapsulated, bonded multi-strand (two to five strands) tendons contained in flat ducts filled with a high-performance cementitious grout that bonds the strands to the surrounding concrete.
Intermediate anchorages provide continuous encapsulation at construction joints. Tendons are protected by both duct and grout.
These bonded multi-strand post-tensioning systems have been successfully applied to commercial building, healthcare and parking structure construction by Trans Fast Post Tension & Prestressed Concrete.
Benefits include enhanced crack and deflection control and a reduction in reinforcing steel. That allows for thin post-tensioning slab design— reducing overall building height which lowers costs for foundation, frame and facade/cladding components. Because bonded tendons may be cut with only localized loss of capacity, another significant advantage of bonded PT is the ease of future building modifications. Design advantages include increased span lengths and load-carrying capacities.
Additionally, the reduction of mild reinforcing steel minimizes the primary sources of corrosion and significantly reduces life cycle maintenance costs.
Bonded post-tensioned concrete is the descriptive term for a method of applying compression after pouring concrete and the curing process.
The concrete is cast around plastic, steel, or aluminium curved duct, to follow the area where otherwise tension would occur in the concrete element.
A set of tendons are fished through the duct and the concrete is poured. Once the concrete has hardened, the tendons are tensioned by hydraulic jacks.
When the tendons have stretched sufficiently, according to the design specifications they are wedged in position and maintain tension after the jacks are removed, transferring pressure to the concrete.
The duct is then grouted to protect the tendons from corrosion.
