Patent EA-005014-B1 (EA)
Title: Corrosion-protected concrete structure, method of constructing and system
Inventor: LYUBLINSKI EFIM YA
IPC: G01N17/02
Filed: 2001-09-19
Abstract: 1. A method of constructing a concrete structure reinforced with steel rebars in which said rebars are embedded in concrete having a pH in the range of about 9 to about 13, characterized in that said bars have a coating of essentially pure aluminum in the range from about 0.25 mm to 2.0 mm thick upon which coating is an oxide layer in the range from about 0.1 mum to about 100 mum thick and comprising aluminum oxide and/or hydrated aluminum oxide in a combined aluminum oxide layer which is in direct contact with said concrete, wherein a corrosion potential sensing means of essentially pure aluminum is embedded into said structure, and the corrosion potential is continuously measured at the surface of said corrosion potential sensing member relative to a reference electrode until the value stabilizes at a measured stable potential without measuring the corrosion potential at said rebars, said source of potential is connected anodically to an anode proximately disposed relative to said rebars, and said rebars are connected cathodically to a source of potential which is sufficiently electronegative with respect to measures stable potential to repress the cathodic potential of said rebars to within a predetermined range correlatable with a corrosion potential measured at said corrosion potential sensing member, and the current from said source of electronegative potential is maintained continuously at a potential in the range of about 150 mV to less than 300 mV lower than the corrosion potential of said corrosion potential sensing means. 2. The method of Claim 1, characterized in that said bars is connected to said source of potential to provide an impressed current at a potential in the range from about -0.9 V to about -1.5 V relative to a HRE. 3. The method of Claim 2, characterized in that the rebars used comprise the coating of essentially pure aluminum and the combined aluminum oxide layer in the range from greater than 0.2 mm thick to about 1 mm thick. 4. A system for the maintenance of a concrete structure reinforced with steel rebars essentially free from corrosion of said rebars, said structure comprising a mass of concrete having a pH of about 9 to about 13, wherein said rebars are electrically interconnected in a grid, said rebars having a coating of essentially pure aluminum in the range from about 0.25 mm to 2.0 mm thick upon which coating is an oxide layer in the range from about 0.1 mum to about 100 mum thick, said oxide layer comprising aluminum oxide and hydrated aluminum oxide, characterized in that it comprises a corrosion potential sensing means, an external power source responsive to programmable control means to which data is transmitted from a comparator means, connected in serial relationship, said programmable control means being responsive to both said external power source and said comparator means, measuring means in said comparator means to continuously measure the corrosion potential at the surface of said corrosion potential sensing means relative to a reference electrode until the value stabilizes at a measured stable potential, means for anodically connecting said external power source of potential to an anode proximately disposed relative to said rebars, means for cathodically connecting said rebars to said external power source which is sufficiently electronegative with respect to said measured stable potential to repress the cathodic potential of said rebars to within a predetermined range, and means for maintaining current from said source of electronegative potential at a potential range of about 150 mV to less than 300 mV lower than the corrosion potential of said corrosion potential sensing means. 5. A corrosion protected structure comprising a mass of concrete having a pH of about 9 to about 13, in which steel rebars coated with aluminium are disposed, characterized in that it comprises a corrosion potential sensing means of essentially pure aluminum embedded within said structure, means to continuously measure the corrosion potential at the surface of said corrosion potential sensing means relative to a reference electrode until the value stabilizes at a measured stable potential, means for anodically connecting an external power source of potential to an anode proximately disposed relative to said rebars, means for cathodically connecting said rebars to said source of potential which is sufficiently electronegative with respect to said measured stable potential to repress the cathodic potential of said rebars to within a predetermined range, and means for continuously maintaining current from said source of electronegative potential at a potential in the range of about 150 mV to less than 300 mV lower than the corrosion potential of said corrosion potential sensing means, wherein said rebars have a coating of essentially pure aluminum in the range of about 0.25 mm to 2.0 mm thick upon which coating is an oxide layer in the range of 0.1 mum to 100 mum thick, said oxide layer comprising aluminum oxide and hydrated aluminum oxide, and a portion of said mass of concrete in a zone within a radius of 10 mm from the surface of said rebars has a pH in the range from 6 to about 9. 6. A corrosion protected structure reinforced with steel rebars, said structure comprising a mass of concrete having a pH in the range of about 9 to about 13, characterized in that it comprises a sacrificial anode in galvanic connection with said rebars and proximally disposed relative to said rebars, wherein said rebars have a coating of essentially pure aluminum in the range of about 0.25 mm to 2.0 mm thick upon which coating is an oxide layer in the range of about 0.1 mum to about 100 mum thick, said oxide layer comprising aluminum oxide and hydrated aluminum oxide. 7. A method of constructing a concrete structure reinforced with steel rebars in which said rebars are embedded in concrete, characterized in that said rebars have a coating of aluminum in the range of about 0.25 mm to about 2.0 mm thick upon which coating is an oxide layer in the range of about 0.1 mum to about 100 mum thick, said oxide layer comprising aluminum oxide and/or hydrated aluminum oxide in a combined aluminum oxide layer which is in direct contact with said concrete, then a corrosion potential sensing means of aluminum is embedded into said structure, and the corrosion potential is measured at the surface of said corrosion potential sensing member relative to a reference electrode until the value stabilizes at a measured stable potential without measuring the corrosion potential at said rebars, said source of potential is connected anodically to an anode proximately disposed relative to said rebars, and said rebars are connected cathodically to a source of potential which is sufficiently electronegative with respect to measures stable potential to repress the cathodic potential of said rebars to within a predetermined range correlatable with a corrosion potential measured at said corrosion potential sensing means, and the current from said source of electronegative potential is maintained continuously at a potential lower than the corrosion potential of said corrosion potential sensing means. 8. The method of Claim 7, characterized in that the rebars used comprise the coating of aluminum and the combined aluminum oxide layer in the range from about 0.2 mm thick to about 1 mm thick. 9. The method of Claim 7, characterized in that the rebars are connected to said source of potential to provide an impressed current at a potential from about -0.6 V to about -1.3 B relative to a HRE. 10. The method of Claim 9, characterized in that the rebars used comprise the coating of aluminum and the combined aluminum oxide layer in the range from about 0.2 mm thick to about 1 mm thick. 11. A system for the maintenance of a concrete structure reinforced with steel rebars, said structure comprising a mass of concrete to receive said steel rebars that are electrically interconnected in a grid, said rebars having a coating of aluminum in the range of about 0.25 mm to about 2.0 mm thick upon which coating is an oxide layer in the range of about 0.1 mum to about 100 mum thick, said oxide layer comprising aluminum oxide and hydrated aluminum oxide, characterized in that it comprises a corrosion potential sensing means, an external power source responsive to programmable control means to which data is transmitted from a comparator means, connected in serial relationship, said programmable control means being responsive to both said external power source and said comparator means, measuring means in said comparator means to continuously measure the corrosion potential at the surface of said corrosion potential sensing means relative to a reference electrode until the value stabilizes at a measured stable potential, means for anodically connecting said external power source of potential to an anode proximately disposed relative to said rebars, means for cathodically connecting said rebars to said external power source which is sufficiently electronegative with respect to said measured stable potential to repress the cathodic potential of said rebars to within a predetermined range, and means for maintaining current from said source of electronegative potential at a potential lower than the corrosion potential of said corrosion potential sensing means. 12. The system of Claim 11, characterized in that the coating of aluminum and the combined aluminum oxide layer is in the range from about 0.2 mm thick to about 1 mm thick. 13. A corrosion protected structure reinforced with steel rebars, said structure comprising a mass of concrete to receive said steel rebars, characterized in that it comprises a corrosion potential sensing means of aluminum embedded within said structure, means to continuously measure the corrosion potential at the surface of said corrosion potential sensing means relative to a reference electrode until the value stabilizes at a measure