Method for electrochemical treatment of porous building materials,

Abstract

An electro-osmotic dewatering procedure is disclosed for removing water from saturated, porous building materials, such as concrete, brick and the like. A controlled, cyclical voltage is applied to an electrode system, to effect osmotic migration of water from an anode electrode, located within the structure or in contact with it, to a cathode electrode, typically spaced from the structure but in electrical circuit with it. The cycle of operations includes a first energy pulse in a direction to effect osmotic migration, followed by a substantially shorter but definite pulse of reverse polarity to prevent or minimize formation of insulating gas films and/or corrosion products. Transition from the primary pulse to the reverse pulse, and from the reverse pulse to the subsequent primary pulse, is at a controlled rate to permit discharge of stored voltage, as a function of inherent capacitance of the system, and to avoid generation of RFI radiations. For treating reinforced concrete, cycling is preferably controlled automatically, as a function of the monitored passivity or non-passivity of the internal reinforcement, so as to avoid creation of corrosion products. Certain aspects of the invention are applicable to other treatments of reinforced concrete, such as realkalization.