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 post-tensioning systems 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 for post-tensioning systems

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.
RIYADH, SAUDI ARABIA, Kingdom of Saudi Arabia
2015 – 2018
KRAKOW, Poland

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