Surface Applied Corrosion Inhibitor

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Title: Surface Applied Corrosion Inhibitor

Author(s): T. A. Burge

Publication: Special Publication

Volume: 193

Issue:

Appears on pages(s): 381-398

Keywords: concrete; durability; corrosion inhibitor

Date: 8/1/2000

Abstract:
Durability limitations of steel reinforced concrete are well documented. Corrosive environments (e.g. the presence of chlorides), carbonation of concrete structures, poor workmanship and other factors can cause corrosion of the reinforcing steel. Normally, reinforcing steel embedded in concrete is protected because the concrete cover acts as a barrier and the high pH value of the pore fluid assures a passive state. Both the presence of chloride ions at concentrations above a given threshold level and carbonation can put reinforcing steel into an active state and result in corrosion rates that markedly decrease the expected service live of reinforced concrete structures. Aqueous surface-applied corrosion-inhibiting impregnations are featuring the ability to reduce the corrosion rate of corroded steel reinforcement embedded in hardened concrete due to their corrosion-inhibiting action and in the case of a carbonated concrete structures by realkalization. Additionally the corrosion rate is further reduced due to the water repellent action of organosilicone compounds. The careful selection of hydroxyalkylamino compounds as well as of inorganic-or organic acid compounds allows the formulation of corrosion-inhibiting impregnations with high buffer capacity. When applied on the surface of a concrete structure, said corrosion-inhibiting compositions are capable of penetrating into the concrete, and raising the pH value of the pore fluid in the vicinity of the reinforcing steel to a level, where the corrosion rate is markedly reduced. Laboratory tests and results from field applications are reported.