Corrosion inhibitors
A surface-applied corrosion inhibitor (SACI) treatment generally consists of the application of a low-viscosity, colourless liquid with concentrated corrosion inhibitors to the concrete’s surface.
This fluid migrates through the porosity of the concrete to the reinforcing steel, stopping corrosion from progressing there, thereby preventing the development of future damage.
The inhibitor migrates through the concrete capillary structure, first by liquid diffusion via the moisture that is normally present in concrete, then by its high vapour pressure, and finally by following hairlines and microcracks.
The diffusion process requires time to reach the rebar’s surface and to form a protective layer.
It is crucial to determine whether corrosion is present and its level to properly dose and apply these preventative treatments.
Corrosion of reinforced concrete is a chemical process that evolves.
Prior to causing visible damage to a structure, it undergoes an invisible process that can last from a few months to several years before the effects of the corrosion reaction become apparent.
Through the use of portable in situ nondestructive devices, it is possible to detect corrosion in its early stages, before visible damage has occurred.
Both new and old concrete can be treated with organic corrosion inhibitors.
These agents are suitable for carbonated concrete or concrete with chloride ion content up to 2% of the cement weight.
For SACI application, the concrete surface must be clean, dry, and free of grease, coatings, soot, dust, moss, saltpetre, efflorescence, or, in general, any substance that may impede product penetration.
Moreover, it is necessary to remove delaminated or deteriorated concrete before application.
Surface-applied corrosion inhibitors can be applied before performing patch repairs with repair mortars or after the mortar has been placed.
Migrating corrosion inhibitors can also be admixed into repair mortar to introduce the inhibitor directly into the patch.
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