Dr Antonio Nanni said: “We have completely replaced the steel reinforcement, the issue of corrosion has totally disappeared.”
Where FRP composites were used and why: The project showcased a number of FRP products, among them was basalt FRP from Galen (manufacturing partner to DEVCO). The presence of noncorrosive reinforcement allowed the use of seawater instead of freshwater in the production of the concrete mix.
SPECIFIC DESIGN DETAILS:
The concrete dock was constructed using precast elements of piles, pile caps and slabs. This structure was designed to withstand wind and wave loads of a category five hurricane.
TYPE OF COMPOSITE USED:
The piles and pile caps were reinforced with FRP rebar in place of steel rebar. The slabs were reinforced with basalt fibre reinforced polymer bars and mesh.
PERFORMANCE IN SERVICE:
Basalt FRP reinforcement is unaffected by chlorides and is highly resistant to acids and alkalis meaning that there is no problem using seawater in the concrete mix.
In addition, recycled aggregates can be added to the new concrete mix, previously this had not been an option due to the fact that there could have been chlorides present within the old concrete which would have attacked the structural steel.
Seawater concrete could help limit water usage freshwater usage and increase the longevity of concrete structures. Currently construction codes prohibit see water-based concrete, but the viability of fibre reinforced polymer as a replacement for steel will open up the industry to a more sustainable and cost-effective alternative.
The use of seawater within the production of concrete would enable concrete production on site eliminating the requirement to transport freshwater.
Bridges are built with a projected ‘50 year’ lifespan, but new designs using composite materials have an expected lifespan of over 100 years. A recent study found that corrosion is responsible for three quarters of maintenance costs on bridges; using FRP instead of steel would greatly reduce these maintenance costs.