Post-tensioning enables the efficient construction of concrete structures, improving structural performance whilst reducing construction time, costs, materials and environmental impact. It is the best friend of developers, architects, engineers and contractors.
What is post-tensioning?
Post-tensioning is an active form of reinforcing that improves the ability of a concrete structure to handle tensile loads by inducing an external compressive load on the structure or element. High-strength steel tendons are positioned in ducts or sleeves before the concrete is placed. Once the concrete gains strength, tension is then applied, pulling the tendons and anchoring them against the outer edges of the concrete before service loads are applied.
Freyssinet’s founder, Eugene Freyssinet, successfully developed prestressed concrete in the 1930s, after recognising that placing concrete under compression maximises its structural performance. He led the first application of post-tensioning on a marine terminal in France in 1933 and now, nearly a century later, the Freyssinet group continues to be at the forefront of post-tensioning technology and innovation – making significant advances in its uses, performance and durability.
Benefits of post-tensioning
By applying post-tensioning, any combination of the following can be achieved:
- Increased spans compared to conventionally reinforced concrete.
- Reduction in concrete and reinforcement for equivalent structures.
- Increased control of deflection and cracking.
- Increased structural ductility; therefore, increased durability.
Post-tensioning is used extensively in bridges, floor slabs, silos and other forms of concrete construction.
In the building sector, Freyssinet has installed post-tensioning systems to a variety of structures, including:
- Residential structures.
- Commercial structures.
- Government infrastructure including hospitals and education facilities.
- Industrial establishments including warehouses, ports and distribution facilities.
|Long design life with low maintenance requirements||Flexibility in design, allowing for more complex shapes/designs||Increased safety of installation||Lighter structures, reduced foundation requirements|
|Improved structural performance||Allows for thinner slabs/longer spans||Fast and efficient construction schedule||Improved structural performance|
|Reduced materials and cost||Flexibility for remedial works or demolition||Economical/reduced cost||Thinner slabs/longer spans, extra floors for the same storey height|
|Increased speed of program||Reduction in materials||Less onsite storage requirement||Deflection control|
|Lower structures through reduced floor depths||Safety of method/system||Reduced materials||Reduction in materials and cost|
|Increased safety of installation||Complete coordinated design to exact standards and code requirements||Allows flexibility for remedial works or demolition|