In untreated concrete, the process of carbonation is nearly impossible to avoid once exposed to the elements. Carbon dioxide slowly penetrates the surface of the concrete reacting to moisture and calcium hydroxide which is found in concrete. This forms calcium carbonate which initially hardens the concrete raising the compressive strength.
Alkalinity then reduces in the concrete and it starts to breakdown. Depending on the permeability, concrete carbonation may advance at a rate of 1 –5mm per year. As carbon dioxide travels deeper into the concrete it reaches the steel reinforcement embedded in the structure.
As the concrete around the steel is broken down by carbonation the corrosive effects of the air and water rust the steel causing it to expand, spall and crack. This in turn causes a high rate of failure to the surrounding area.
The concrete repairs contractor would cutout the area around the spalled steel, removing concrete back to sound substrate. The exposed steel would then be cleaned and prepared back to bright steel before treatment to protect it in the future.
The concrete repair mortar of choice is used to fill out the repair area. The surface area of the concrete structure can then be prepared by abrasive or water blasting and a fairing coat applied to bring the structure back to its original depth. Finally, a waterproof coating is applied.
DWI (Drinking Water Inspectorate) approved products are also available. These systems can be supplied and installed by our fully qualified and experienced operatives.
Our teams all have CSCS Cards, EUSR Water Cards and Confined Space Certificates.
Technique provide refurbishment services, concrete repairs and protective coatings