Long-term Performance of Repairs to Reinforced Concrete Exposed to Coastal Conditions

Abstract

Reinforced concrete (RC) specimens were treated using different combinations of surface coating and/or patch repair methods and materials, left in a coastal region with frost damage risk, and their properties characterized after 25 years of exposure. Specimens were prepared by chipping away concrete from one section of concrete block with embedded reinforcement bars to expose the bars, followed by patch repair and then surface coating. Four types of material were used for patch repair: cement mortar, styrene-butadiene rubber (SBR) polymer cement mortar, rust-resistant SBR polymer cement mortar, and lightweight epoxy mortar. Two types of material were used for surface coating: multi-layer textured and thin textured coating. Following exposure, cracks were visible only on the surfaces of untreated specimens, apparently due to rebar corrosion; they were absent from all specimens that had undergone surface coating and/or patch repair. In addition, the corrosion resistance of these methods and materials was investigated by measuring and comparing the surface areas of corroded rebar between three segments: the repaired part, the unrepaired part, and the boundary between them. Concrete carbonation and rebar corrosion were greatly dependent on surface coating material, with the multilayer-textured coating especially effective at blocking chloride penetration. In addition, rebar corrosion was more effectively prevented by patch repair with the SBR polymer cement mortar than with the lightweight epoxy mortar.

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