UHPC Ductal overlay
After 45 years of service, the Chillon viaducts (Switzerland) received a concrete overlay to extend their life and meet current seismic codes. These viaducts were opened in 1969, and began to deteriorate from water infiltration and corrosion.
Reinforced and sealed with Lafarges ultra-high performance concrete (UHPC) Ductal, the bridges, the jewels of the Swiss motorway network, will continue to connect cities for a long time, between France and Switzerland. The UHPC was applied in a 4.5 cm thick layer. It was batched on site with a mix that allowed for it to be placed on a slope of up to 10%.
Benefits of UHPC overlay
- Improve structural behavior of the deck (rigidity) and resistance
- Increases strength of existing superstructure when composite action is provided
- Increases longitudinal rigidity at a fraction of the thickness of traditional reinforced concrete
- Densely packed fine particles stop the ingress of water that could trigger Alkali Aggregate Reactions (AAR), while rendering the overlay weatherproof
- Steel fibers give tensile strength hardening which prevent cracking, spalling, and scaling, even under heavy stress from road traffic and deicing chemicals
- Reduces load on existing structures (by using low quantities of UHPC), contributing to their overall integrity and longevity
- Can also be used to rehabilitate a deck instead of a full deck replacementy
- Quick to implement
- Highly cost effective: job time reduced, structure lifetime extended and lower maintenance costs
Potential UHPC overlay uses
Deck repair | Suspended slabs
UHPC ductal can be used to waterproof new and existing residential and commercial decks.
UHPC ductal can be used over wood substrates without membranes as it has such a high flexural strength.
Pedestrian and road traffic bridge decks can be re surfaced therefore greatly extending service life.