SEDL / STP / STP691-EB / STP36059S

Concrete Overlays for the Protection of Reinforced Concrete Against Corrosion

Manning, DG
Research officer and concrete testing engineer, Ministry of Transportation and Communication, Downsview, Ont.

Chojnacki, B
Research officer and concrete testing engineer, Ministry of Transportation and Communication, Downsview, Ont.

Pages: 13    Published: Jan 1980

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Abstract

Portland cement and modified portland cement concrete overlays were placed on reinforced concrete base slabs containing differing quantities of added chlorides. The specimens were ponded intermittently with sodium chloride solution. Concrete overlays were effective in retarding the penetration of chloride ions. Resistance to chloride penetration was improved by decreasing the water/cement ratio of the concrete and by the use of a latex modifier or internally sealing with wax. Initially high concentrations of chloride ions within the base concrete were redistributed within the base and the overlay. The concrete overlays caused a decrease in corrosion activity of reinforcing steel embedded in concrete containing more chloride than the chloride content corrosion threshold. Cracks accelerated the onset of corrosion of intercepted reinforcing bars.