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Figueira da Foz Bridge
Rehabilitation of the Figueira da Foz bridge and its accesses. Repair of the pylons in the north and south towers.
The pylons of the tower foundations of the Figueira da Foz bridge showed signs of expansive reactions. The crack patterns found on the head (starting from the concrete joints approximately 1 m from the top) showed evidence of fractures in volume resulting from alkaliaggregate reaction.
The upper section of the pylons showed advanced signs of corrosion of the reinforcement with peeling of the concrete coating, undoubtedly due to the high level of chloride and depassivation of the reinforcements via carbonation of the concrete.
Assuming that the permanently submerged area did not exhibit any signs of reinforcement corrosion due to lack of available oxygen, the following methodology was adopted.
- Deep, complete repair of a strip measuring approximately 1 m in height across the entire periphery of the top of the eight pylons, by replacing a thickness of some 8 cm of the concrete coating with structural shotcrete applied dry with dual-chamber machines.
- Deep, complete repair of a strip measuring approximately 4m in height across the entire periphery of the top of the eight pylons, by replacing a thickness of some 8 cm of the concrete cover with structural shotcrete applied dry with dual-chamber machines.
- Superficial repair, pitting some 2 cm and correcting the reinforcement coating to 5 cm in the other areas exposed during low water, not subject to deep repair.
- Coating of the North pillar pylons starting from the central section during minimum low-water depth, with the APE composite encapsulation system.
- Carbon fibre laminates measuring 60 x 1.4 mm, low module – 200GPa, were applied for structural reinforcement, with a 1.5 cm thick layer of mortar sprayed on to increase the mechanical protection of the fibres.
- Coating of the repaired tidal strip by applying an epoxy coating of the TRIECOPRIMER type.
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State of deterioration of the pylons before the repair work – North Tower Pylons.
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Demolition of deteriorated concrete and reconstruction of reinforcements.
