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Abstract

A process and system for rehabilitating mature concrete structures, which have become carbonated and/or infused with chlorides and thus represent a corrosive environment for internal reinforcing steel. The surface of the concrete is first repaired with a special mortar having resistivity and capillarity consistent with the parent concrete and the process requirements. An elongated, flat, flexible, ribbon-like electrode element is supported in spaced relation over the surface of a concrete area to be treated, being threaded back and forth and oriented in edgewise fashion to the concrete surface. Thereafter a self-adherent, cohesive mixture of delignified cellulose pulp fibers and a liquid electrolyte solution is sprayed onto the surface of the concrete, to a level to cover and embed the ribbon-like electrode element, forming an electrolytic medium associated with the electrode element. A DC voltage is impressed between the internal reinforcement and the embedded electrode element to effect electro-chemical chloride removal and/or realkalization of the concrete in a procedure of finite time duration. Preferably, the electrode strip is passed about conductive supports at one side of the treating area, so that the voltage is connected to the electrode strip at a plurality of locations. Flame and smoulder retardants are mixed with the dry cellulose fibers in advance of being applied to the concrete, by spraying through the previously mounted electrode structure.

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First Claim