1997 Fiscal Year Final Research Report Summary
Mechanisms of Combined Effects of AAR and Reinforcement Corrosion on Concrete
| Project/Area Number |
08650530
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
土木材料・力学一般
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| Research Institution | KANAZAWA UNIVERSITY |
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Principal Investigator |
KAWAMURA Mitsunori KANAZAWA UNIVERSITY,Graduate school of Nat.Science & Tech PROFESSOR, 大学院・自然科学研究科, 教授 (20019730)
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| Co-Investigator(Kenkyū-buntansha) |
TORII Kazuyuki KANAZAWA UNIVERSITY,FACULTY OF ENGINEERING PROFESSOR, 工学部・土木建設工学科, 教授 (50115250)
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| Project Period (FY) |
1996 – 1997
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| Keywords | Sodium Nitrite / Calcium Nitrite / Ettringite / Corrosion / Steel Bar / ASR Gel / Interfacial Transiiton Zone / Sulfate Ion |
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| Research Abstract |
We could propose a new thought on the mechanisms of the promotion of ASR due to sodium chloride and sea water through detailed experiments concerning the effects of externally supplied sea water and sodium chloride solution on ASR and the process of ASR chemical reaction in mortars with and without NaCl. Furthermore, the changes in pore solution composition with time at various depths from the surfaces of specimens and their relation to the corrosion of reinforcement steel bars in the specimens were elucidated. Another important result was a finding on the relation between the effectiveness of nitrites and the pore solution composition in mortars containing the nitrites.
The major results obtained were summarized as follows ;
(1) The Cl-/OH- ratios in mortars in 0.51Mm NaCl solution were greater than in sea water at 360 daysafter, immersion. The formation of dense layrs aragonite and brucite might hinder the intrusion of the Cl- ions into mortar cylinders and the leakage of OH- ions from them.
(2) From a point of view of the pore solution composition, far greater corrosion degree in steel bars in reactive. aggregate-containing mortars was unexpected.
(3) Replacement of greater amounts of reactive aggregate for standerd sand in mortars resulted in less degree of corrosion in steel bars except one case. The depression of corrosion in reactive aggregate-containing mortars in sea water and NaCl solution appears to result from the formation of homogeneous ASR gel layrs surrounding the steel bars.
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