Protection of reinforced concrete structure by means of migratory corrosion inhibitors, Estel Building, Barcelona.

Introduction.

As part of the work to change the use of the building, the concrete structure has been protected using Corrosion Migratory Inhibitors, located in the Eixample district of Barcelona, in the block bounded by Avinguda Roma and the streets Calàbria, Viladomat and Mallorca, adding more than 50,000 square metres of offices and services.

Making repairs to structures more corrosion resistant and therefore more durable will result in fewer repairs, greater structural integrity and a longer service life, which will also result in greater sustainability of the building.

Intervention.

In the case in question, this is an intervention where in a first phase, carried out in 2018, the concrete structure was repaired by applying concrete repair mortars.

The current intervention consists of protecting the structure from the marine environment of Barcelona. By applying Molins CORTEC MCI 2021, a surface sealant that uses a mixture of reactive silicates, surface activating agents and migratory corrosion inhibitors to protect the reinforced concrete against corrosion, to the pillars and slabs of the floor slabs on all floors.

CORTEC MCI 2021 is applied to the dry, clean and free of impurities surface on the elements to be protected. The application is carried out by spraying, until saturation of the support, between 1 and 3 coats, depending on the porosity of the concrete.

This protective layer reaches and adheres to the surface of the reinforcement, providing much more effective protection against moisture than that provided by the passivation layer of the steel in alkaline pH. It also more than doubles the chloride threshold required for attack, as well as reducing the rate of corrosion of the reinforcement once it starts. The use of corrosion inhibitors provides a very significant increase in the durability of the structure.

Technical note

The phenomenon of corrosion can be defined as a process of electrochemical destruction or deterioration of a metal by action and reaction of the metal with the surrounding medium (simultaneous oxidation and reduction reactions).

In order for electrochemical corrosion to start, a galvanic battery must be formed, therefore, there must be an anode, a cathode, an electrolyte (wet concrete) and oxygen; in this electrochemical system, the armature acts as anode and cathode, allowing the connection between both electrodes and, consequently, the passage of electrons between them.