Protectosil^® Corrosion Control - How it Works

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Protectosil^® CIT penetrates concrete and provides an organofunctional molecule to inhibit the electrochemical corrosion process between the rebar and the chloride ions, oxygen and moisture present in the concrete.

The corrosion process in steel-reinforced concrete is spontaneous and similar to the process in a galvanic cell or battery. Water is only one aspect of corrosion. Water molecules bind electrostatically to concrete, forming the conductive medium for the chloride-ion induced corrosion process that dissolves the rebar. The electrochemical reactions can be described (see below).

The iron oxides (rust) formed in the corrosion process take up more volume than the original steel causing stress on the concrete. These stresses manifest themselves as cracks, spalls and delaminations in the concrete structure. But the main consequence of concrete corrosion is the loss of steel cross-section and the resulting loss of structural capacity. The three main factors affecting the corrosion rate are the concentration of chloride ions, moisture and oxygen. Other factors, such as temperature, also contribute to the speed of the corrosion process.

The proprietary organofunc-tional chemistry of Protectosil^® CIT greatly reduces corrosion currents. This is done chemically by interrupting the electrolytic current and causing a decrease in the corrosion process.

Protectosil^® CIT interrupts the corrosion mechanism

Water entering into building substrates is one of the most significant causes of damages. In challenging weather conditions, this may result in freeze-thaw or salt burst. But

water is only one reason for damaged steel-reinforced concrete.

The real cause of rust on steel-reinforcement bars and the consequent mechanical stress is chloride induced corrosion. Water molecules bind electrostatically to concrete, forming the conductive medium for the chloride induced corrosion process that dissolves the rebar.

Protectosil^® CIT efficiently counteracts both mechanisms. First, Protectosil^® CIT provides a deep barrier that blocks water, and thus chloride ions, from reaching the rebar. Second, Protectosil^® CIT’s organofunctional chemistry interrupts the electrolytic current, causing a substantial

reduction in corrosion current and the by-product rust. An independent study has proved that three other commercial corrosion inhibitors “did not show any benefit in

inhibiting the corrosion of chloride contaminated reinforced steel*“ while “Protectosil^® CIT by Degussa effectively reduced corrosion under the conditions of the ASTM G-109 procedure** “.

* J.E. Bennett, Consultants Inc. / Investigation of topically applied inhibitors to mitigate corrosion in reinforced concrete using modified ASTM G-109 procedure / Report Feb. 2004

** J.E. Bennett, Consultants Inc. / Investigation of Protectosil^® to mitigate corrosion in reinforced concrete using modified ASTM G-109 procedure / Report November 29th 2005