Abstract: Corrosion protection of steel in concrete is provided by locating an anode assembly including both a sacrificial anode and an impressed current anode in contact with the concrete and providing an impressed current from a power supply to the anode. The impressed current anode forms a perforated sleeve surrounding a rod of the sacrificial anode material with an activated ionically-conductive filler material between. The system can be used without the power supply in sacrificial mode or when the power supply is connected, the impressed current anode can be powered to provide an impressed current system and/or to recharge the sacrificial anode from sacrificial anode corrosion products.

Abstract: In a method of corrosion protection of rebar in concrete the sacrificial anode is held in place by wrapping a first wire around a first rebar portion and a second wire at second rebar portion and twisting together the first and second free ends to tension the wrappings. This can be used either on two separate rebars which are parallel or at right angles or can be used at longitudinally spaced positions on a single rebar where the rebar roughening prevents the two wrappings from sliding as the wires are tensioned by the twisting. In many cases a covering material such as a porous mortar is cast onto the outer surface of the anode and in this case the mortar and the wire are located such that the wire exits from the sacrificial anode at a position separate from the layer of covering material.

Abstract: Cathodic protection of steel in concrete is provided by locating an anode assembly including both a sacrificial anode and an impressed current anode in contact with the concrete and providing an impressed current from a power supply to the anode. The impressed current anode forms a perforated sleeve surrounding a rod of the sacrificial anode material with an activated ionically-conductive filler material between. The system can be used without the power supply in sacrificial mode or when the power supply is connected, the impressed current anode can be powered to provide an impressed current system and/or to recharge the sacrificial anode from sacrificial anode corrosion products.

Abstract: Cathodic protection of steel in concrete is provided by locating an anode assembly including both a sacrificial anode and an impressed current anode in contact with the concrete and providing an impressed current from a power supply to the anode. The impressed current anode forms a perforated sleeve surrounding a rod of the sacrificial anode material with an activated ionically-conductive filler material between. The system can be used without the power supply in sacrificial mode or when the power supply is connected, the impressed current anode can be powered to provide an impressed current system and/or to recharge the sacrificial anode from sacrificial anode corrosion products.

Abstract: A sacrificial anode assembly for cathodically protecting and/or passivating a metal section, comprising: (a) a cell, which has an anode and a cathode arranged so as to not be in electronic contact with each other but so as to be in ionic contact with each other such that current can flow between the anode and the cathode; (b) a connector attached to the anode of the cell for electrically connecting the anode to the metal section to be cathodically protected; and (c) a sacrificial anode electrically connected in series with the cathode of the cell; wherein the cell is otherwise isolated from the environment such that current can only flow into and out of the cell via the sacrificial anode and the connector. The invention also provides a method of cathodically protecting metal in which such a sacrificial anode assembly is cathodically attached to the metal via the connector of the assembly, and a reinforced concrete structure wherein some or all of the reinforcement is cathodically protected by such a method.

Abstract: Cathodic protection of steel in a building or other concrete or similar structure is provided by locating an anode in a suitable location adjacent to the steel and providing an impressed current from a power supply to the anode. The anode is formed from a material which is more electro-negative than the steel so that in the event that the power supply falls below the galvanic potential therebetween, current flows under galvanic action to replace the impressed current. A diode in the circuit prevents flow of current across the power supply but allows the galvanic current when the power supply fails open circuit. An additional diode can be provided in the event the power supply fails closed circuit to prevent reverse current flow.

Abstract: Cathodic protection of steel in a building or other concrete or similar structure is provided by locating an anode in a suitable location adjacent to the steel and providing an impressed current from a power supply to the anode. The anode is formed from a material which is more electro-negative than the steel so that in the event that the power supply falls below the galvanic potential therebetween, current flows under galvanic action to replace the impressed current. A diode in the circuit prevents flow of current across the power supply but allows the galvanic current when the power supply fails open circuit. An additional diode can be provided in the event the power supply fails closed circuit to prevent reverse current flow.

Abstract: A sacrificial anode assembly for cathodically protecting and/or passivating a metal section, comprising: (a) a cell, which has an anode and a cathode arranged so as to not be in electronic contact with each other but so as to be in ionic contact with each other such that current can flow between the anode and the cathode; (b) a connector attached to the anode of the cell for electrically connecting the anode to the metal section to be cathodically protected; and (c) a sacrificial anode electrically connected in series with the cathode of the cell; wherein the cell is otherwise isolated from the environment such that current can only flow into and out of the cell via the sacrificial anode and the connector. The invention also provides a method of cathodically protecting metal in which such a sacrificial anode assembly is cathodically attached to the metal via the connector of the assembly, and a reinforced concrete structure wherein some or all of the reinforcement is cathodically protected by such a method.

Abstract: Corrosion protection of steel in concrete is provided by locating an anode assembly including both a sacrificial anode and an impressed current anode in contact with the concrete and providing an impressed current from a power supply to the anode. The impressed current anode forms a perforated sleeve surrounding a rod of the sacrificial anode material with an activated ionically-conductive filler material between. The system can be used without the power supply in sacrificial mode or when the power supply is connected, the impressed current anode can be powered to provide an impressed current system and/or to recharge the sacrificial anode from sacrificial anode corrosion products.