VSL designs, manufactures and installs durable, state-of-the-art post-tensioning systems that comply with international standards and approval guidelines for both new and existing structures.

In the early fifties, post-tensioning systems for the pre-stressing of concrete was developed by specialists, such as VSL in Switzerland.

This technique consists in introducing an internal stress state into a concrete element, with the installation and stressing of post-tensioning tendons. This comes to counteract stresses due to external loading, and results in reduced deformation and cracking of concrete.

Post-tensioning has revolutionized the design and construction of concrete structures, in particular bridges: It has permitted to extend the application of concrete for larger spans, and has enabled the development of new construction methods, making construction simpler and faster.

Solutions for any application

VSL post-tensioning technology includes several systems that are specifically designed for different applications and requirements. The choice of a suitable system can be made by considering three key criteria:

  1. Type of structural element: the depth of the structural element influences the type of system to be used:
    • Multistrand tendons are usually used for structural elements with medium to large depths (bridge girders, beams in buildings…)
    • Slab tendons with flat ducts are generally used for thin structural elements (slabs)
  2. Structural design: taking account of structural design requirements
    • An internal or external post-tensioning system, or a combination of both, is adopted for multistrand tendons
    • For slab tendons, a bonded or unbonded post-tensioning system may be chosen
  3. Required Protection Level (PL) to protect the tendon from corrosion attacks: the tendon encapsulation is chosen depending on the required protection level – PL1, PL2, PL3 as defined by the FIB Bulletin 33.
Working procedures – key for quality

As an experienced specialist contractor, VSL carries out high quality installation using trained personnel and reliable equipment, in accordance with well-proven procedures.

One of the key procedures is about grouting, which comes to protect the tendon from corrosion attacks.

Structural monitoring

VSL offers various accessories and services for structural monitoring such as:

  • Grout Void sensors and monitoring guarantee that the tendon has been properly filled with grout and confirm the grout properties,
  • Electrically Isolated Tendons (EIT) allow for long-term monitoring of tendon encapsulation and detection of the exact location of any possible defect,
  • In-service monitoring for special structures such as nuclear power plants.


Discover our Case Studies

Here is a selection of our references.
DUBAI, United Arab Emirates

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