External tendons for bridges
VSL’s external tendons are designed for long-term performance, ease of inspection, and fast installation. With individually protected strands and no need for grouting, they provide robust corrosion protection, simplify maintenance, and adapt to both new bridges and retrofit applications.
Why choose VSL external tendons system
VSL has reimagined external post-tensioning by introducing a new generation of tendons designed for performance, safety, and maintainability.
VSL’s external tendons include:
- Individually protected strands with no need for grouting
- Advanced corrosion protection meeting exceeding requirement of highest standards and recommendations
- Full inspectability and strand replaceability throughout the tendon’s life
- Compatibility with both new construction and structural strengthening
- Proven performance through full-scale testing and international validation
- Integration-ready for Smart PT monitoring and condition-based asset management
Compare the VSL System with Market Solutions Protected by Cement Grout
| Conventional Systems protected by cement grout | VSL XT-series | |
|---|---|---|
| Stress Redistribution | Strand failure increases stress on adjacent strands. | Each strand is isolated—no force redistribution. |
| Tension Monitoring | Tension remains unchanged despite strand loss; no alert triggered. | Tension changes are detectable and triggers an alert. |
| Visual Inspection | Geometry unchanged; no visible sign of damage. | Sag increases visibly—damage is easy to spot. |
| Operational Impact | Sudden failure leads to emergency repairs and traffic restrictions. | Damage is detected early; repairs can be planned without disruption. |
Key features
Applications
VSL’s external tendons are used in:
- Cast-in-place and precast box girder bridges
- Extradosed bridges and hybrid PT–cable systems
- Composite bridges (steel–concrete)
- Bridge strengthening and re-tensionable systems
- Geometrically complex layouts or structures with limited internal space
Design and Performance
The VSL external tendon system includes:
• Individually protected strands in HDPE sheaths
• GC casting or E-plate: compact, fatigue-resistant, EIT-ready for railway bridges
• XT-deviator assembly with post-installed pads for optimal guidance and durability
• Flexible PE duct and guide supports: smooth curvature, low friction
• Enhanced corrosion protection: compliant with long-term exposure standards
• Maintained parallel strand geometry: consistent load distribution and easy monitoring
Accessories
- EIT anchorages for railway projects
- Deviator supports and sealing collars to prevent strand damage
- VSL XT-pads to guide and protect strands in deviator zones
- Vacuum injection of anchor blocks for long-term durability
- Can be installed with additional grouted pipe for fire & mechanical protection when required.
End-to-End Services
- Strands inserted post-concreting, using pulling or pushing techniques
- No grouting operations required for corrosion protection, reducing installation time
- Compact site equipment and fewer wet works
- Ideal for bridges with limited access, tight curvature, or retrofit constraints
- Safe de-tensioning and replacement operations possible, using VSL-patented techniques
Carbon Impact
VSL’s external tendon system supports sustainable infrastructure through:
- Lower material volumes and simplified detailing
- No grout usage, reducing cement-related emissions
- Reusable anchor zones and long design life with minimal intervention
- EPD-certified components, including GC anchorage (2.24 kg CO₂e/kg)
Key benefits
- No grouting required for corrosion protection, saving time and reducing complexity
- Tendon full protection from installation: no temporary protection required
- Strands remain parallel and accessible from anchorage to anchorage
- No risk of full tendon failure with individual strand loss
Frequently asked questions ABOUT VSL EXTERNAL TENDONS
They allow for visual inspection, strand replacement, and are faster to install—with no grouting step.
Each strand is individually sheathed in HDPE from end to end, meeting highest protection levels as applicable for stay cables.
Yes. The system is designed for easy de-tensioning and single or full strand replacement, if needed.
Absolutely. These tendons are used for both new construction and retrofits, including full bridge upgrades.
Yes. It meets or exceeds major post-tensioning and corrosion protection codes, including EIT configuration.