The structure subject to this intervention is the runway head of Madeira International Airport, which supports the embankment beneath the runway and, by extension, the regional expressway that borders it. The original design of this runway head was developed by Prof. Dr. Edgar Cardoso, who conceived a special reinforced concrete structure composed of 10 vaults, each approximately 45 cm thick, supported by 11 buttresses on the seafront.

Intervention goal

The vaults and buttresses exhibited visible signs of degradation caused by high concentrations of chlorides in the concrete, which were measured well above the critical threshold for the onset of reinforcement corrosion. At the time of the structural inspection, more than 50% of the surface area of the buttresses and 10% of the vault surfaces showed concrete delamination. The solution adopted to address the pathological condition involved the replacement of contaminated concrete and reinforcement in the buttresses, and the application of an active cathodic protection system with impressed current using activated titanium anodes (Ti/MMO) on the vaults.

Intervention stages and techniques

The intervention in the vaults followed the following methodology:

– Repair of concrete delamination areas;

– Marking and opening in concrete of horizontal and vertical swirls for the placement of anode and current distribution tapes and windows for the installation of anodic, cathodic and monitoring sensors;

– Close of swirls and windows with pre-dosed mortar;

– Performing current injection tests in independent electrical zones

– Installation of the electrical wiring and its connection to the power units;

– Calibration and maintenance of the cathodic protection monitoring system.

Results

After one year of monitoring, the data show compliance with depolarisation of all protected zones and that the potential recorded in all electrodes indicates that the reinforcements are in a passive state in accordance with EN ISO 12696:2022.

Additional information

This structure is considered critical to the operation of Madeira International Airport, the only airport on the island, and is located in a marine environment. Together with the reconstruction of the buttresses and the complete repainting of the structure, the cathodic protection of the vaults is vital to ensuring the durability of the runway head and the continued operation of the airport.

Technique applied

Cathodic protection system with impressed current using Ti/MMO anodes applied across the entire surface of the vaults

Technical Team