Freyssinet, Inc., as principal contractor, undertakes installation, associated repair work, and application of coatings. Clients benefit by not having numerous relationships with a variety of inter-dependent sub-contactors, the responsibility for successful project implementation is clearly defined.
Reinforcement corrosion is the major cause of deterioration of concrete structures. Good quality concrete provides a highly alkaline surrounding to steel reinforcement. If this alkalinity reduces, the reinforcement becomes increasingly susceptible to corrosion. The expansive forces caused by corrosion and rust formation are sufficient to cause concrete to crack and spall, leading to a need for concrete repair. There are two main mechanisms that cause concrete deterioration: Carbonation and Chloride Attack. Carbonation is caused by atmospheric carbon dioxide, which dissolves in water to form carbonic acid. This acid progressively penetrates and reacts with concrete, reducing the pH value from 13 to 9; at the reinforcement layer, the steel is de-passivated, and begins to corrode. De-icing salts, seawater and marine aggregates are common sources of chlorides. Where chlorides are able to penetrate down to the reinforcement layer they will aggressively attack the steel, starting corrosion. The rate of both carbonation and chloride attack depend on concentration of carbon dioxide in the atmosphere / chlorides at the concrete surface, concrete permeability / density, and concrete moisture content. Cracked or poor quality concrete will deteriorate faster.
Conventional patch concrete repairs to damaged
concrete are unlikely to be successful where carbonation has progressed
behind the reinforcement layer, or where chlorides remain in sufficient
concentration in adjacent untreated concrete. Cathodic protection, which
works by passing a small electric current through the reinforcement layer,
has several significant advantages over other available techniques: it
is a continuous process that both stops existing corrosion and prevents
future attack, it is a permanent ongoing solution that does not require
reapplication, it is suitable for severely damaged concrete, it is effective
against both carbonation and chloride attack, its effectiveness can be
controlled and monitored, and it is more economic than complete replacement.
It is particularly suited to highway and marine structures where re-contamination
Foreva® solutions can be used to control the progression of corrosion of reinforcements in reinforced concrete structures at all of its stages of development by:
Foreva® GP Zinc