Vasco da Gama Bridge

The protection consists of applying fibreglass plates and then injecting an epoxy grout with high adherence in damp conditions between the casing and the pillar, a system marketed as A-P-E™.

Themain factor in this job was the difficult access to the work areas. Personnel, materials, and equipment gained access via the river using vessels and platforms, subject to the River Tejo's conditions in terms of wind, swell, and tide (see photo 2).

Two working teams were created to install the A-P-E™ system. On land, one team prepared the 42 casings to be installed, and the other team installed the system on the pillars.

All concrete surfaces where the fibreglass casings were to be applied were first prepared with high pressure fresh water to remove all marine organisms and loose materials from the outer layer.

The A-P-E™ concrete surface protection system comprises a translucent fibreglass-reinforced polyester covering applied 12 mm from the concrete surface, with the gap filled by an injection of epoxy and fine silica aggregate grout. The installation of this system on the south viaduct pillars of the Vasco da Gama bridge was monitored by a technician from the American company Madcon, Bruce Trader, with wide experience in applying the system.

Each pillar's encapsulation (with a circumference of approximately 6.5 m) consisted of three sections, spliced, according to the manufacturer's specifications, by bonding with epoxy resin and riveting with stainless steel rivets.

After arriving at each pillar, the fibreglass casings were sealed and bound to avoid deformation during injection (photo 3). The bottom part was sealed using Stapox AS epoxy grout, since it was possible to work on this area in dry conditions at low tide.

Finally, the A-P-E™ Pile Grout was injected, thus filling the "coffered" gap formed by the FGRP casing (photos 4 and 5). The epoxy grout was injected using a constant flow dual component injection pump.

This encasing system, used for the first time in Portugal for this job, makes it possible to solve complex problems at water level or underwater, like expansive alkali-aggregate reactions and those caused by sulfates, or just to treat degraded surfaces of underwater structures (dams, bridges, quays).