1992 Fiscal Year Final Research Report Summary
Basic Study on Cathodic Protection for Repairing of Prestressed-Concrete Structures Damaged by Chloride Corrosion of Reinforcement
| Project/Area Number |
03650394
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
コンクリート工学・土木材料・施工
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| Research Institution | Kagoshima University |
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Principal Investigator |
TAKEWAKA Koji Kagoshima Univ., Faculty of Eng., Associate Prof., 工学部, 助教授 (10155054)
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| Project Period (FY) |
1991 – 1992
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| Keywords | Prestressed-Concrete Structures / Cathodic Protection / Corrosion of Reinforcement / Repairing Method / 100mV Shifting Criterion / Over-Protection Problem / Field Examination of Repairing / Permanent Form with Anode |
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| Research Abstract |
Cathodic protection is expected to be a practical corrosion protection system for newly and repaired concrete structures in marine environment. In this study, some laboratory and field examinations were carried out for the establishment of high reliability on the cathodic protection for repairing prestressed-concrete structures. The following results were obtained :
(1) -100mV shifting criterion for cathodic protection can not be accomplished satisfactorily for corrosion protection of reinforcements in concrete. 150-200mV depolarization may be necessary to stop the corrosion in severe corrosion environment such as atmospheric dry and wet cyclic condition in marine environment.
(2) In the case of cathodic protection on prestressed-concrete structures, the possibility of reduction of strength of prestressed-concrete strand is found at over-protection-level current density, and cracking of concrete may also occur at that current density level, due to the high pressure of hydrogen evolution. Therefore, it is necessary that cathodic protection should not be over-protected absolutely on pretension type prestressed-concrete structures, regardless of condition of concrete and surrounding atmosphere.
(3) From the field examination of repairing the reinforced-concrete garage by the cathodic protection, it is confirmed that the cathodic protection can be useful on concrete structures affected by drying for relatively long time. And even polish condition of reinforcement is influenced by the repairing effect of cathodic protection of corroded concrete structures.
(4) The permanent form with anode of cathodic protection on concrete structures is developed, as the anode system construction is simplified and its durability is enhanced.
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