Benefits
Since it was patented in 1928, post-tensioning has gradually evolved into a multi-faceted and sophisticated engineering technique. In traditional pre-tensioning the steel cable or strand is stressed before the concrete is poured around it: in post-tensioning, the strand is housed in ducts and is not tensioned untill the concrete has been poured and has hardened. In both systems, the steel is positioned to carry the structural tensile stresses, leaving the concrete to carry compressive loads.
The benefits gained using post tensioning in structures are;
1. Larger spans.
2. Thinner slabs and beams.
3. Larger pours
4. Reduced floor to floor heights.
5. Reduced conventional reinforcement.
6. Reduced number of columns.
7. Reduced weight of the structure, therefore smaller and fewer footings.
8. Early formwork stripping, therefore faster construction.
9. Reduced crane time since the components are fewer and lighter.
10. Improved deflection control.
11. Overall reduced construction costs.
Post Tensioned Slab systems offer more environmentally sustainable construction with reduced concrete/cement aggregates consumption, reduced total steel content and the associated reduction in production energy consumption. When demolition is required recycling is easier as the concrete is readily separated due to the reduced steel content.