Cathodic Protection of Steel in Concrete

Book Cover......Page 1
Half-Title......Page 2
Title......Page 4
Copyright......Page 5
Contents......Page 6
List of Contributors......Page 15
1.1 INTRODUCTION......Page 16
1.2 ELECTROCHEMICAL CORROSION......Page 18
1.3 CORROSION OF STEEL......Page 19
1.4 STEEL IN CONCRETE......Page 21
1.4.1 Mechanisms......Page 25
1.4.1.1 Alkalinity and chloride concentrations......Page 27
1.4.1.3 Cement type......Page 30
REFERENCES......Page 31
2.1 INTRODUCTION......Page 33
2.2.2.2 Chloride contamination......Page 34
2.3.3 Detailed investigation......Page 35
2.3.4.1 Delamination and visual surveys......Page 36
2.3.4.3 Half-cell potential survey......Page 37
2.3.4.4 Chloride ion content......Page 38
2.3.4.5 Carbonation depth measurements......Page 39
2.3.4.6 Measurement of corrosion rates......Page 40
2.3.5 Assessment of results of investigation......Page 41
2.4.1 Introduction......Page 42
2.4.2 Structural considerations......Page 43
2.4.3.1 Patch repairs......Page 44
2.5.1 General......Page 45
2.5.2 Effectiveness of cathodic protection......Page 46
2.5.4 Adverse side effects......Page 47
2.6 NEED FOR AND LIMITATIONS ON PATCH REPAIRS IN CASES WHERE CATHODIC PROTECTION IS TO BE USED......Page 48
2.7.3 Embedded metals and fixings......Page 49
REFERENCES......Page 50
APPENDIX 2.1 CATHODIC PROTECTION OF REINFORCED CONCRETE......Page 51
3.2 SYSTEM DESIGN......Page 53
3.2.2 Current density requirement......Page 54
3.2.3 Current distribution......Page 55
3.2.4 Trials and testing......Page 57
3.2.5 Zones......Page 58
3.2.7 Cabling......Page 59
3.2.8 Reference electrodes and other measuring devices......Page 61
3.2.10 Continuity and negative connections......Page 64
3.3.1 Introduction......Page 66
3.3.3 Support columns......Page 67
3.3.4 Beams......Page 69
3.3.5 Radial bents......Page 70
REFERENCE......Page 73
4.1 INTRODUCTION......Page 74
4.2 APPLICATION OF IMPRESSED CURRENT CATHODIC PROTECTION......Page 75
4.3.1 Aesthetics......Page 76
4.3.2 Physical attributes......Page 77
4.3.4 Performance characteristics......Page 78
4.4 IMPRESSED CURRENT CATHODIC PROTECTION ANODES CURRENTLY AVAILABLE......Page 80
4.4.1 Materials......Page 84
4.4.2.2 Platinized, mixed metal-oxide-coated titanium and brass or stainless-steel plates......Page 86
4.4.2.4 Carbon-fibre tapes......Page 87
4.4.3.1 Conductive coatings......Page 88
4.4.3.3 Metal spray coatings......Page 91
4.4.3.4 Other surface-mounted anode systems......Page 92
4.4.4 Discrete anodes......Page 93
4.4.4.1 Platinized titanium wire/graphite paste systems......Page 94
4.4.5 Embeddable surface-mounted anodes......Page 95
4.4.5.1 Mixed metal-oxide-coated titanium mesh systems......Page 96
4.4.5.3 Metal-oxide-coated titanium ribbons......Page 97
4.4.5.5 Cementitious overlay materials......Page 98
4.4.6 Anodes for submerged and buried structures......Page 99
4.4.6.2 Consumable anodes......Page 100
4.4.6.4 Sacrificial anodes......Page 101
4.4.7.1 Technical considerations......Page 102
4.4.7.2 Economic considerations......Page 104
4.5 THE FUTURE......Page 105
REFERENCES......Page 106
ACKNOWLEDGEMENTS......Page 107
5.1 GENERAL......Page 108
5.2.1 Manual tap transformer plus rectifier......Page 109
5.2.2 Transformer plus rectifier plus smoothing circuit......Page 110
5.2.4 Linear......Page 111
5.3.1 Protection against transients and lightning......Page 113
5.3.1.2 Transient protection diodes......Page 114
5.3.2 Cabinet selection......Page 115
5.3.3 Reading output currents, voltages and potentials......Page 118
5.3.4 Galvanic separation of power supplies......Page 119
5.3.5 Power supply layout......Page 120
5.3.7 Efficiency......Page 121
5.4 AUTOMATIC SYSTEMS......Page 122
6.1 INTRODUCTION......Page 128
6.2 BASIS OF CATHODIC PROTECTION......Page 129
6.3 CATHODIC PROTECTION OF STEEL IN CONCRETE......Page 133
6.4 ELECTRICAL CRITERIA......Page 134
6.4.1.1 Basis of criterion......Page 135
6.4.2.1 Basis of polarization curves......Page 137
6.4.2.2 The measurement of polarization curves......Page 138
6.4.3.1 Basis of depolarization criterion......Page 139
6.4.4 Other criteria......Page 141
6.4.4.3 Macrocell probes......Page 142
6.4.4.4 Electrical resistance probes......Page 143
6.5 DISCUSSION OF POSSIBLE ELECTRICAL CRITERIA......Page 144
BIBLIOGRAPHY......Page 148
7.1 INTRODUCTION......Page 149
7.2 UPGRADING AND MAINTAINING DURABILITY......Page 150
7.3 ALTERNATIVE TECHNOLOGIES TO CP......Page 152
7.4 CP USING MMO ANODES......Page 154
7.5 DESIGN CONSIDERATIONS......Page 156
7.6 EXAMPLES OF NEW STRUCTURE CP......Page 161
7.7 OPERATION AND MAINTENANCE......Page 164
REFERENCES......Page 167
8.1.1 Overview......Page 169
8.1.2 Description of electro-osmosis......Page 170
8.1.3 Initial survey of structure......Page 171
8.1.6 Anode mesh......Page 172
8.1.9 Electrolyte reservoir......Page 173
8.1.12 Coffer tanks......Page 174
8.1.14 Performance monitoring......Page 175
8.1.18 Comparison with other methods of treating carbonated concrete......Page 176
8.2.1 Overview......Page 177
8.2.4 Testing......Page 178
8.2.6 Comparison with other methods of treating chloride contaminated concrete......Page 179
8.2.7 Possible detrimental side effects of realkalization and desalination......Page 180
8.2.9 Bond strength......Page 181
8.2.11 Microcracking......Page 182
8.3 ELECTROCHEMICAL INHIBITORINJECTION......Page 183
REFERENCES......Page 184
9.1 HYDROGEN EMBRITTLEMENT OF PRESTRESSING WIRES......Page 185
9.2 CORROSION INTERACTION......Page 188
9.3 REDUCTION IN BOND STRENGTH AND ALKALISILICA REACTION......Page 189
REFERENCES......Page 190
10.1 INTRODUCTION......Page 192
10.3.1 Direct costs......Page 193
10.3.3 Maintenance costs......Page 195
10.4 COST IMPLICATIONS OF ANODE TYPE......Page 196
10.6 CATHODIC PREVENTION......Page 197
10.7 PROTECTING THE INVESTMENT......Page 199
REFERENCES......Page 200
Index......Page 201