※一部利用できない機能があります
| 1.
論文 |
論文
|
鳥居, 和之 ; 川村, 満紀 ; Torii, Kazuyuki ; Kawamura, Mitsunori
概要:
金沢大学理工研究域環境デザイン学系<br />Recently, chemical soil stabilization are actively adopted for the improvement of the soft ground
…
on which roads or buildings will be constructed. In addition to traditional stabilizers of Potland cement and lime, the industrial by-products such as fly ash and pulverized blastfurnace slag are also used for the purpose of increasing the effectiveness of cement and lime as a stabilizer and their effective utilization in soil stabilization. The objective of this study is to reval the mechanisms of strength development of the compacted stabilized soils from a microstructural view-point. The compressive strength, modulus of deformation and pulse velocity of various compacted soils stabilized with cement, lime and lime-fly ash (or pulverized blastfurnace slag) were measured. Their microstructures were also characterized by the SEM observation and pore size distributions obtained by the mercury intrusion porosimeter. The relationships between strength and changes in microstructure in compacted stabilized soils are discussed.
続きを見る
|
||||
| 2.
論文 |
論文
|
HA, Tuan Minh ; Fukada, Saiji ; Torii, Kazuyuki ; 深田, 宰史 ; 鳥居, 和之
概要:
金沢大学理工研究域環境デザイン学系<br />Structural responses have been used as inputs in the evaluation procedures of civil structures fo
…
r years. Apart from the degradation of a structure itself, changes in the environmental conditions affect its characteristics. For adequate maintenance, it is necessary to quantify the environment-induced changes and discriminate them from the effects due to damage. This study investigates the variation in the vibration responses of prestressed concrete (PC) girders, which were deteriorated because of the alkali-silica reaction (ASR), concerning ambient temperature and humidity. Three PC girders were exposed to outdoor weather conditions outside the laboratory, one of which had a selected amount of fly ash in its mixture to mitigate the ASR. The girders were periodically vibration tested for one and a half years. It was found that when the temperature and humidity increased, the frequencies and damping ratios decreased in proportion. No apparent variation in the mode shapes could be identified. A finite element model was proposed for numerical verification, the results of which were in good agreement with the measured changes in the natural frequencies. Moreover, the different dynamic performances of the three specimens indicated that the fly ash significantly affected the vibrations of the PC girders under ASR deterioration. © 2017 Tuan Minh Ha et al.
続きを見る
|
||||
| 3.
論文 |
論文
|
Ha, Tuan Minh ; Fukada, Saiji ; Torii, Kazuyuki ; 深田, 宰史 ; 鳥居, 和之
概要:
金沢大学理工研究域環境デザイン学系<br />In the Hokuriku region, alkali-silica reaction (ASR) caused severe degradations in many concrete
…
bridges. However, criteria for repair and replacement works of these structures are still unclear. For the development of damage evaluation procedure, it is necessary to investigate the load-carrying capacity of prestressed concrete (PC) girders affected by ASR-induced deterioration in actuality. This study constructed two full-size PC specimens from the high-early-strength Portland cement and reactive aggregates, and then exposed them to outdoor environmental conditions. One of them was specially mixed with a controlled amount of fly ash. After one and a half years of outdoor exposure, destructive loading tests were carried out to investigate the difference in loading capacity of the girders. From results of the long-term exposure and the tests, the flexural strength and the rigidity of the specimen with fly ash were not degraded while ASR was also effectively suppressed. In addition, cylindrical concrete cores were taken at different positions of both girders to analyze the relationship between mechanical properties of concrete such as compressive strength, static elastic modulus, and ultrasonic wave propagation speed. Results of the coring test showed that the mechanical properties of concrete cores varied according to their collecting positions and directions. © 2017 Japan Concrete Institute.<br />出版者照会(事後報告)
続きを見る
|
||||
| 4.
論文 |
論文
|
鳥居, 和之 ; 川村, 満紀 ; 枷場, 重正 ; 五十嵐, 心一 ; Torii, Kazuyuki ; Kawamura, Mitsunori ; Hasaba, Shigemasa ; Igarashi, Shinichi
概要:
金沢大学理工研究域環境デザイン学系<br />In the regions of the cold weather, the deterioration of the subbase in roads by freezing-thawing
…
action is often observed. Although the durability of stabilized soils is considered to be important, the evaluation of the resistibility of stabilized soils against freezing-thawing cycles has been little established in general. The purpose of this study is to evaluate the resistibility of the various stabilized soils against freezing-thawing cycles in terms of the compressive strength of the stabilized soils undergoing freezing-thawing cycles. The relationship between the resistibility against the freeezing-thawing cycles and the microstructure in the stabilized soils is discussed on the basis of the pore size distributions.
続きを見る
|
||||
| 5.
論文 |
論文
|
Torii, Kazuyuki ; Sannoh, Chikao ; Kanitani, Maki
|
||||
| 6.
論文 |
論文
|
Hashimoto, Tohru ; Torii, Kazuyuki
|
||||
| 7.
論文 |
論文
|
Hashimoto, Tohru ; Torii, Kazuyuki
概要:
In the Hokuriku district, the effort toward the production of highly durable concrete mixtures using classified fine fly ash has just started as a part of ongoing countermeasures for the chloride attack and the alkali silica reaction
…
(ASR). At a time when ASR deterioration phenomena are still progressing, the use of fly ash cement in concrete should be recommended and assertively be adopted as a regional approach for the mitigation of ASR problem especially in the Hokuriku District. In order to promote this mutual understanding and cooperation among the electric power companies, the national and local governments, the industrial association of ready-mixed concrete companies and the universities are indispensable. Accordingly, a joint-collaborative industry-academia-government research committee has been set up in January 2011. This paper focuses on the drawing from the current stage of ASR problem in the Hokuriku district and the development of highly durable fly ash concretes as its countermeasures.
続きを見る
|
||||
| 8.
論文 |
論文
|
Hashimoto, Tohru ; Torii, Kazuyuki
概要:
In the Hokuriku district, the effort toward the production of highly durable concrete mixtures using classified fine fly ash has just started as a part of ongoing countermeasures for the chloride attack and the alkali silica reaction
…
(ASR). At a time when ASR deterioration phenomena are still progressing, the use of fly ash cement in concrete should be recommended and assertively be adopted as a regional approach for the mitigation of ASR problem especially in the Hokuriku District. In order to promote this mutual understanding and cooperation among the electric power companies, the national and local governments, the industrial association of ready-mixed concrete companies and the universities are indispensable. Accordingly, a joint-collaborative industry-academia-government research committee has been set up in January 2011. This paper focuses on the drawing from the current stage of ASR problem in the Hokuriku district and the development of highly durable fly ash concretes as its countermeasures.
続きを見る
|
||||
| 9.
論文 |
論文
|
Torii, Kazuyuki ; Kubo, Tetsuji ; Sannoh, Chikao ; Kanitani, Maki
概要:
In the Hokuriku district in Japan, large numbers of concrete structures have been suffering from damage caused by alkali
…
silica reaction (ASR). Some huge volcanoes are located within this district, and the headwaters of main rivers prompt the outflow and spreading of volcanic rocks such as andesite, rhyolite and tuff stones, which are the main volcanic reactive stones causing the serious damage of ASR in the entire area. To solve this problem effective countermeasures such as repair and strengthening methods should be established. One intake tower in this area had deteriorated due to ASR, and deformation had occurred as a consequence of ASR ex-pansion of the concrete. Countermeasures were carefully considered by academic experts, and post-tensioned tendons were inserted into the intake tower concrete (vertically oriented) so that the power station can continue to operate safely in the future. This is thought to be the first challenge of its type anywhere in the world for which the deformation of a real structure caused by ASR expansion must be controlled. In this paper, the results obtained from laboratory tests using reactive aggregate and the overview of the investigation and the method of the reinforcement including the effect of the countermeasures will be discussed.<br />出版者照会済
続きを見る
|
||||
| 10.
その他 |
その他
|
馬場崎, 亮一 ; 鳥居, 和之 ; 嘉門, 雅史 ; 青木, 正雄 ; 吉田, 信夫 ; Torii, Kazuyuki ; Kamon, Masashi ; Aoki, Masao ; Yoshida, Nobuo
概要:
金沢大学理工研究域環境デザイン学系
|
||||
| 11.
論文 |
論文
|
Torii, Kazuyuki ; Kubo, Tetsuji ; Sannoh, Chikao ; Kanitani, Maki
概要:
In the Hokuriku district in Japan, large numbers of concrete structures have been suffering from damage caused by alkali silica reaction (ASR). Some huge volcanoes are located within this district, and the headwaters of main rivers
…
prompt the outflow and spreading of volcanic rocks such as andesite, rhyolite and tuff stones, which are the main volcanic reactive stones causing the serious damage of ASR in the entire area. To solve this problem effective countermeasures such as repair and strengthening methods should be established. One intake tower in this area had deteriorated due to ASR, and deformation had occurred as a consequence of ASR ex-pansion of the concrete. Countermeasures were carefully considered by academic experts, and post-tensioned tendons were inserted into the intake tower concrete (vertically oriented) so that the power station can continue to operate safely in the future. This is thought to be the first challenge of its type anywhere in the world for which the deformation of a real structure caused by ASR expansion must be controlled. In this paper, the results obtained from laboratory tests using reactive aggregate and the overview of the investigation and the method of the reinforcement including the effect of the countermeasures will be discussed.
続きを見る
|
||||
| 12.
その他 |
その他
|
千田, 昌平 ; 鳥居, 和之 ; 榎, 明潔 ; Torii, Kazuyuki
概要:
金沢大学理工研究域環境デザイン学系
|
||||
| 13.
論文 |
論文
|
Sugiyama, A. ; Torii, Kazuyuki ; Sakai, K. ; Shimizu, K. ; Sato, Y.
概要:
金沢大学理工研究域環境デザイン学系<br />A large number of bridge piers on the Noto highway are now suffering from serious damages caused
…
by alkali-silica reaction (ASR). The Kashima Bridge with a 2-span steel girder structure was constructed in 1978. However, in the inspection carried out in 2004, it was found that half of stirrup steel bars in the pillow beam fractured at the bending corner of steel bar due to the excessive ASR expansion of concrete. For this reason, the pillow beam of the Kashima Bridge was completely reconstructed by removing all the concrete in 2005. In the first part of the paper, the execution procedure of reconstruction of pillow beam and the strengthening of column in ASR-affected RC pier were introduced. In the second part of the paper, in order to recycle concrete rubbles from the Kashima Bridge, the possibility of recycled aggregates for residual ASR reactivity and its some countermeasures were also discussed. © 2008 Taylor & Francis Group.全文公開200909
続きを見る
|
||||
| 14.
論文 |
論文
|
Kobayashi, Jun ; Kizu, Ryoichi ; Torii, Kazuyuki
概要:
金沢大学大学院自然科学研究科環境創成<br />金沢大学薬学部<br />In recent years, there have been many attempts to reuse molten slag. Molten slag is
…
obtained through further treatment of incinerated ash produced in the disposal process of garbage or sewage sludge and is used in building materials, such as brick. To establish the safety of such slag, its physical properties and metal contents were investigated in this study. After examining the physical and chemical characteristics of 13 forms of slag made using different methods, no differences were observed and it was judged that reuse is possible. There was little elution of toxic metals in the elution test when water was used as a solvent. On the other hand, when acid and alkali were used, the elution of toxic metals tended to become greater. © 2004 The Pharmaceutical Society of Japan.
続きを見る
|
||||
| 15.
その他 |
その他
|
参納, 千夏男 ; 鳥居, 和之 ; Sanno, Chikao ; Torii, Kazuyuki
概要:
[研究概要]
|
||||
| 16.
その他 |
その他
|
野村, 昌弘 ; 鳥居, 和之 ; Nomura, Masahiro ; Torii, Kazuyuki
概要:
[研究概要]
|
||||
| 17.
その他 |
その他
|
三原, 守弘 ; 鳥居, 和之 ; Mihara, Morihiro ; Torii, Kazuyuki
概要:
[研究概要]
|
||||
| 18.
論文 |
論文
|
鳥居, 和之 ; Torii, Kazuyuki
概要:
金沢大学理工研究域環境デザイン学系<br />コンクリート電柱や枕木などのコンクリート製品では，蒸気養生やオートクレーブ養生を実施しており，アルカリシリカ反応（ASR）とともに遅延型エトリンガイト生成 (DEF)によるひび割れ発生の危険性が
…
高まることが知られている。そこで本研究では，北陸地方で製造されたコンクリート電柱のASRおよびDEFによる劣化現象の実態調査結果に基づき，コンクリート製品工場でのフライアッシュコンクリートによる防止対策と標準化を目指すことにした。<br />In the electrical concrete poles and concrete railway sleepers, which the steam curing or autoclaved curing have been normally conducted in the process of production, the deterioration due to Alkali-silica Reaction (ASR) and/or Delayed Ettringite Formation (DEF) may be occurred, which leading to a serious cracking of precast concrete products. Therefore, in the research work of this study, firstly, the actual deterioration cases due to ASR and/or DEF in electrical concrete poles were collected all over the Hokuriku district. Based on the results of this survey, both the effective use of fly ash concretes in the mitigating ASR and/or DEF and the standardization of fly ash concretes in all precast concrete factories of electrical concrete poles were successfully proposed.<br />研究課題/領域番号:15K06163, 研究期間(年度):2015-04-01 – 2018-03-31
続きを見る
|
||||
| 19.
論文 |
論文
|
鳥居, 和之 ; Torii, Kazuyuki
概要:
金沢大学理工研究域環境デザイン学系<br />北陸地方では、塩害やASRによるコンクリート構造物の劣化が顕在化しており、新しく建設する社会インフラである橋梁やトンネルには高い耐久性が求められている。一方、同地方では、近年、フライアッシュの品
…
質管理の手法が確立され、フライアッシュを使用したコンクリートは塩害やASRに対する抵抗性が優れていることが判明した。この成果より、実際のPC橋梁やプレキャスト製品（PC杭、PC電柱）におけるフライアッシュコンクリートの実用化が成功した。<br />In the Hokuriku district, a higher durability performance of infrastructures such as bridges and tunnels, which are newly constructed, is now required because the deterioration of concrete structures due to chloride attack and/or ASR becomes very sever and significant. On the other hand, in this district, at present, the production and quality control system of high-quality fly ashes is established, and the fly ash concrete is very superior to the durability against chloride attack and ASR. Based on the results of research work, the practical use of fly ash concrete for PC bridges and PCa products such as piles and concrete poles has been successfully carried out.<br />研究課題/領域番号:24360169, 研究期間(年度):2012-04-01 – 2015-03-31
続きを見る
|
||||
| 20.
論文 |
論文
|
鳥居, 和之 ; Torii, Kazuyuki
概要:
放射性廃棄物からの高濃度アルカリ塩によるコンクリートのアルカリシリカ反応(ASR)とその防止対策を、各種ナトリウム塩に浸漬したモルタルバーの膨張挙動より実験的に検討した。その結果,外部から浸透するナトリウム塩の種類により,モルタルバーの膨張
…
量が相違することや、高濃度のナトリウム塩の浸透によるモルタルのASR発生機構を解明できた。さらに,ポゾラン材料(フライアッシュおよび高炉スラグ微粉末)を多量に混和することがその防止対策として有効であった。<br />In this research, the mechanisms of alkali-silica reaction(ASR) in concrete induced by high concentration solutions of sodium salts were investigated. For this purpose, the expansion behavior of mortar bars immersed in various sodium salts was experimentally compared. In sodium nitrate and sodium sulfate solutions, the process of formation of complex compound hydrates and thereby the rise in the concentration of hydroxide ion was the main reason of ASR. Furthermore, the addition of large amounts of fly ash and blast-furnace slag was very effective in controlling the expansion of mortar bars.<br />研究課題/領域番号:21560483, 研究期間(年度):2009-2011
続きを見る
|
||||
| 21.
論文 |
論文
|
鳥居, 和之 ; Torii, Kazuyuki
概要:
本研究の成果は以下の3つの項目に分けることができる。まず, (1)再生骨材からのアルカリ溶出がASRに及ぼす影響を検討した結果, 再生骨材中のASRゲルから溶出するアルカリによってASRが促進することが明らかになった. 次に, (2)再生骨
…
材を使用したコンクリートのASRによる膨張性状を検討した結果, コンクリートのアルカリの種類(NaCl添加またはNaOH添加)とその添加量を種々に変化させたコンクリートバーの膨張試験の結果に基づいて, 再生骨材を使用したコンクリートのASRの発生条件の特徴とぺシマム混合率との関係を明らかにした. さらに, (3)原骨材のASRの程度が再生骨材コンクリートの膨張性状に及ぼす影響を検討した結果, 建設後約30年が経過したASR劣化構造物から製造した能登産の安山岩砕石を原骨材とする再生骨材は反応領域が骨材界面から1~2mm程度に限定されていたのに対して, 常願寺川産の川砂利から製造した再生骨材は安山岩粒子の内部まで反応が激しく進行していた. このため, 再生骨材のASR試験及び再生骨材コンクリートの膨張試験の結果より, 再生骨材のアルカリシリカ反応性は原骨材の種類とその反応性(能登産の安山岩砕石および常願寺川産の川砂利)により相違し, それらは促進養生条件下での再生骨材コンクリートの膨張性状に大きな影響を及ぼすことが判明した.<br />研究課題/領域番号:19560458, 研究期間(年度):2007-2008<br />出典：「再生骨材におけるASRに関連した問題解決のための基礎研究」研究成果報告書 課題番号19560458（KAKEN：科学研究費助成事業データベース（国立情報学研究所））（https://kaken.nii.ac.jp/report/KAKENHI-PROJECT-19560458/19560458seika/)を加工して作成
続きを見る
|
||||
| 22.
論文 |
論文
|
鳥居, 和之 ; Torii, Kazuyuki
概要:
本研究の成果は以下の4つの項目に分類することができる.(1)鉄筋破断による劣化事例調査---石川県内では,平成18年の時点で,せん断補強筋および帯鉄筋に関しては,橋脚の枕梁6基,柱部2基,フーチング4基で,橋台の本体4基,フーチング4基で,
…
鉄筋破断が確認された.主鉄筋に関しては,橋脚の枕梁3基で圧接部のはずれ(破断面は平滑であり,施工不良が原因と推察される)を確認した.橋脚以外では,鉄筋コンクリート堤体2基,トンネル坑口1基で,同様な鉄筋破断を確認した.(2)鉄筋破断のメカニズム解明---破断した鉄筋は鉄筋の径がD16からD32の範囲の電炉鉄筋であった.鉄筋の曲げ加工部の破断面は,絞りがなく,脆性的であった.鉄筋破断面は3つの破壊過程(1次亀裂,2次亀裂および3次亀裂の形成とそれらの進展過程)に分類することができ,ASRによる鉄筋破断のメカニズムを提案した.(3)ASR劣化橋梁のアセットマネージメント---橋梁のアセットマネージメントには,橋梁の劣化度,補修・補強の要否,費用の算定などを記載したデータベースの作成が不可欠となる.能登有料道路以外の,能登地方の橋梁(昭和61年以前のものを対象)のASR発生状況を詳細に調べた結果,奥能登では橋梁数347の内の166のもの(48%),中能登では橋梁数263の内のもの(23%),加賀では橋梁数417の内の64のもの(15%)に,ASRによる劣化の兆候があることが判明した.(4)ASR劣化橋脚の補強およびモニタリングの技術開発---ASR劣化橋脚では,鉄筋破断が発生した枕梁を鋼製支保工で仮受けした後に,打替えることに決めた.ASR劣化橋脚の補強技術は未確立であるので,モニタリングを同時に実施し,その計測結果を今後の補強設計に反映させた.現在も,能登有料道路では打替えを実施した橋脚や補強したフーチング,供用中のトンネルなどで自動計測によるモニタリングを実施している.<br />Research results obtained in this study are summarized as follows ;(1)Investigation on fracture of steel bars in ASR-affected structuresResearch works revealed that the embrittle fracture of steel bars at the bending corner of stirrup or bent-up steel bars, due to excessive expansion of concrete due to ASR, occurred in the pillow beam or footing of piers and the abutment in bridges located in Ishikawa Prefecture, leading to the significant loss of structural integrity of concrete elements.(2)Mechanisms of fracture of steel bar due to ASRIn the pillow beam or foundation of bridge pier, a lot of stirrup steel bars fractured at the bending corners, without any elongation of steel bar. The fracture surface of steel bar seemed to be very flat and smooth, which indicated the typical embrittlement fracture of steel bar. Whether or not the fracture of steel bars may be associated with the stress corrosion cracking and/or the hydrogen embrittlement fracture was discussed.(3)Asset management for ASR-deteriorated bridgesFor all bridge piers located in Ishikawa prefecture, which is considered to be the most serious ASR case in Japan, the degree of deterioration of bridge pier due to ASR was investigated by the visual inspection of cracking. Corresponding to the classification of ASR deterioration level of each bridge pier, the repair/strengthening method and maintenance procedure were proposed.(4)Strengthening and monitoring of ASR-deteriorated bridge piersIn the case study of the pillow beam of Kashima Bridge and the foundation of Tokuda No.2 Bridge in Ishikawa Prefecture, the degree of deterioration of bridge pier due to ASR was also investigated by the non-destructive inspection. Based on the classification of ASR deterioration level of each element, the most appropriate strengthening methods were adopted for them. In the maintenance of these bridges, the monitoring using crack sensors was successfully applied in order to ensure the daily safety of these bridges.<br />研究課題/領域番号:16360218, 研究期間(年度):2004-2006<br />出典：「鉄筋破断が発生したASR劣化橋脚の調査診断及び補強技術の実用化のための研究開発」研究成果報告書 課題番号16360218 (KAKEN：科学研究費助成事業データベース（国立情報学研究所）) 本文データは著者版報告書より作成
続きを見る
|
||||
| 23.
論文 |
論文
|
鳥居, 和之 ; Torii, Kazuyuki
概要:
「泰平橋」(平成12年8月撤去)の解体では,PC・T桁の一般図及び配筋図(PC鋼線,スターラップ筋,横締め構造など)を完成するとともに「泰平橋」で使用したコンクリート及びPC鋼線(直径5nmのピアノ線)の品質を調べた.その後,平成12年10
…
月に(株)ピー・エス七尾工場(現(株)ピーエス三菱)にて,PC桁の曲げ及びせん断載荷試験を公開試験として実施し,50年が経過したPC・T桁の耐荷力及び変形性能を明らかにした.次に「長生橋」(平成13年8月撤去)の解体では,「泰平橋」と同様にPCスラブ桁の一般図および配筋図を完成するとともに,「長生橋」で使用したコンクリート及びPC鋼線(直径3mmのピアノ線)の品質を「泰平橋」と比較検討した.その後,'平成13年10月に(株)ピーエス七尾工場(現(株)ピーエス三菱)にて,PC桁本体及び合成桁の曲げ及びせん断載荷試験を公開試験として実施した.「長生橋」は移設検討委員会(座長:金沢大学工学部川村満紀教授)が設置され,復元の方法および移設の場所が検討された,移設検討委員会の方針に従って,平成14年4月に建設当時の欄干や電気灯などを復元し,「長生橋」は七尾市の希望の丘公園に移設された.また,「泰平橋」,「長生橋」に関する調査資料を整理し,歴史的価値の高い両橋梁の記録を冊子としてまとめるとともに,平成14年11月に特別講演会「コンクリートは本当に丈夫で長持ちか」を主催し,「泰平橋」,「長生橋」の調査結果を多くの土木関係者に報告した.さらに,解体調査の記録を2本のビデオ(金沢大学工学部編集,(株)ピーエス三菱編集)にまとめた.<br />The Chousei bridge and the Taihei bridge are the first prestressed concrete bridges (PC) in Japan, which were constructed in 1953 and 1954 across the Misogi river in Nanao city in Ishikawa Prefecture. After symbolizing the birth of PC bridge in Japan for 50 years, the bridge was earmarked for relocation as part of an urban development project. They were dismantled in August 2000 and in September 2001. Following its removal, some of the girders were subjected to examination and load testing to determine both the physical and chemical properties of old concrete and the load-bearing capacity of old bridge. The water to cement ratio of the concrete was found to be as low as 33 % and it texture was also very dense. This proves that the concrete mixed for bridge is very durable, which results in no carbonation of concrete and little corrosion of stee bars and PC wires in concrete. The bending and shearing load capacity of girders of the gbridge was also found to be satisfactory for the requirements of specifications of road bridges. After the test, the Chousei bridge was relocated to the memorial park on the outskirts of Nanao city.<br />研究課題/領域番号:13650503, 研究期間(年度):2001-2002<br />出典：「我が国で最初のプレストレストコンクリート橋(長生橋,泰平橋)の解体調査」研究成果報告書 課題番号13650503 (KAKEN：科学研究費助成事業データベース（国立情報学研究所）) 本文データは著者版報告書より作成
続きを見る
|
||||
| 24.
論文 |
論文
|
鳥居, 和之 ; Torii, Kazuyuki
概要:
1.エコセメントの鉄筋腐食に及ぼす高炉スラグ微粉末の効果塩水噴霧環境下にてエコセメントを使用したモルタル中の鉄筋腐食を自然電位,分極抵抗および交流インピーダンスによる電気化学的モニタリングと鉄筋の腐食減量および腐食面積率の測定により実施した
…
。その結果,エコセメントの一部を高炉スラグ微粉末で置き換えることにより、塩化物イオンのモルタルへの浸透性が大きく低下するので、鉄筋腐食の開始時期が遅れる。しかし、鉄筋の腐食限界値以上の塩化物イオンが浸透した場合には、高炉スラグ微粉末の置換率が大きくなると鉄筋を保護する水酸化カルシウムが存在しないので、それ以後の鉄筋腐食が急激に進行することが判明した。2.エコセメントの鉄筋腐食に及ぼす含有塩化物の影響近年、エコセメントの塩化物を低減するように製造工程が改良され、低塩化物形のエコセメントが開発されている。1の試験概要と同様な手法で、高塩化物形および低塩化物形のエコセメントを使用したモルタル中の鉄筋腐食を比較検討した。その結果,塩水噴霧環境下であっても、低塩化物形のものは高塩化物形のものと比較してモルタル中の鉄筋腐食性状が改善される。高炉スラグ微粉末による改善効果は高塩化物形のものと低塩化物形のもので大きな相違が見られない。また、電気化学的測定は、鉄筋腐食の推定に有効であり、とくにAPインピーダンスの軌跡より鉄筋腐食の開始時期が正確に判定できることが判明した。<br />Ecocement is a new type of hydraulic cement produced from incinerator ash. However. the incinerator ash contains large amounts of chloride, which, if not removed during the production process, is expected to accelerate the corrosion of steel bars when ecocement is used in reinforced concrete structures. The chlorides can be removed in the production process but at a high cost. Two types of ecocement have been produced, a high chloride type (type I) and a low chloride (type II). This paper investigates the corrosive behavior of steel bars embedded in the mortars containing both types of ecocement, cured under and exposed to wetting and drying cycles. Corrosion of the mild steel bars was monitored by halfcell potential, polarization resistance, and AC impedance measurements. The relative performance of the two types of ecocements with respect to the corrosive behavior of the embedded steel bars was discussed.From the results, the following conclusions could be drawn.(1) Steel bars embedded in mortars of high-chloride type ecocement is more susceptible to corrosion than that of low-chloride type one.(2) Carbonation accelerates corrosion of steel bars embedded in the mortars of both ecocements, although the effect is higher in high-chloride type than in low-chloride type.(3) Electrical measurement yields a good result in the monitoring of corrosion of steel bars embedded in cement mortars.(4) In both types of ecocement, the extent and severity of the corrsion of the embedded steel bars depend on the water to cement ratio, the higher the water to cement ratio, the greater the severity of corrosion.<br />研究課題/領域番号:11650465, 研究期間(年度):1999-2000<br />出典：「都市ゴミ焼却灰より作製したセメントのキャラクタリゼーションと鉄筋腐食性状」研究成果報告書 課題番号11650465(KAKEN：科学研究費助成事業データベース（国立情報学研究所）) 本文データは著者版報告書より作成
続きを見る
|
||||
| 25.
論文 |
論文
|
鳥居, 和之 ; Torii, Kazuyuki
概要:
ASR損傷コンクリート橋脚の補修・補強対策を確立する目的で、樹脂塗装表面処理工法、鋼板巻き立て工法およびPC鋼材巻き立て工法により補修・補強したモデル柱試験体を使用した屋外暴露試験および圧縮載荷試験を実施した後に、実際に、ASR損傷コンクリ
…
ート橋脚のPC鋼材巻き立て工法による補強が行なわれた。今回の一連の研究で得られた成果をよとめると次のようである。モデル試験体の圧縮載荷試験の結果より、(1)PC鋼材によりプレストレスを与えると、ASRひび割れの進展が抑制される、(2)PC鋼材がコンクリートの軸方向応カと軸方向歪みの関係に与える影響はASRによる損傷を受けたコンクリートに対しても受けていない健全なコンクリートと同様である、(3)PC鋼材で巻き立てることにより、コンクリートの強度および靭性を大きく改善できる、ことが確認された。モデル試験体の屋外暴露試験の結果より、(1)ASRの進行は日射や降雨などの局所的環境の影響を大きく受けるが、表面被覆材による塗装のASR抑制効果は小さい、(2)鋼板巻き立て工法およびPC鋼材巻き立て工法により補強した試験体では長期にわたってASRによる膨脹の抑制およびひび割れの拘束効果が認められる、(3)鋼板巻き立て工法では温度による影響のため試験体に発生する歪みに南北方向の相違が見られる、ことが確認された。上記の研究成果を受けて、平成8年度および平成9年度に能登有料道路のASR損傷コンクリート橋脚のPC鋼材巻き立て工法による補強工事が実施された。両橋脚では、補強前よりASRによる損傷のモニタリングが行なわれており、ASR損傷橋脚の調査、施工および補強設計の記録が付録の資料としてまとめられている。<br />A new strengthening method with prestressing steel wires, which is named the PC confined method, has been developed especially for ASR damaged RC piers. Reinforced concrete columns, 300 mm in diameter and 900 mm high, were prepared in order to examine the effects of the prestressing force around the concrete column on the confinement of the cracks of concrete due to alkali-silica reaction and on the improvement of load-carrying capacity and ductility of damaged concrete columns.From the experimental results, it was concluded that the prestressing force given around the concrete column could effectively confine the cracks due to ASR and decrease the expansion of concrete. Thus, it was found that both the strength and ductility of damaged RC column was much improved by PC confined method. Based on the results of the laboratory test, the PC confined method was successfully adopted in the strengthening for ASR damaged RC piers of the Toyokawa bridge and the Kumakigawa bridge in Noto peninsula in Ishikawa prefecture in 1997 and 1998, respectively. The measurements on changes with time in the stress and strain of concrete in the piers of the Toyokawa bridge after strengthening by PC confined method are now monitored.<br />研究課題/領域番号:09650504, 研究期間(年度):1997-1998<br />出典：「PCコンファインド工法によるASR損傷鉄筋コンクリート橋脚の補強に関する研究」研究成果報告書 課題番号09650504 (KAKEN：科学研究費助成事業データベース（国立情報学研究所）) 本文データは著者版報告書より作成
続きを見る
|
||||
| 26.
論文 |
論文
|
鳥居, 和之 ; Torii, Kazuyuki
概要:
コンクリート構造物のアルカリシリカ反応に及ぼす電気防食の影響を検討することを目的として、反応性骨材を含有するコンクリート梁試験体を対象として約3年間屋外にて電気防食試験を実施した。その結果、電気防食の実施によりASRによるひび割れが促進され
…
、梁の耐荷力も低下することから、今後橋梁などで電気防食を実施する際には事前調査として使用されている骨材の反応性の有無を確認することが重要であることが明らかになった。今回の一連の研究の成果をまとめると次のようである。電気防食を実施した梁試験体の屋外暴露試験より、(1)電気防食の実施によりアルカリの総量規制値(3kg/m^3)を下回るものにもASRによるひび割れが発生する、(2)梁試験体のASRによる膨脹は温度依存性があり、季節変動を反映した階段状の膨脹挙動を示す、(2)エポキシ樹脂.塗装による水分の遮断はASRの抑制効果は小さい、(3)電気防食のASRに及ぼす影響はコンクリートのコンクリートの配合(水セメント比および単位セメント量)によって相違する、ことが明らかになった。屋外暴露終了後の梁試験体の曲げ載荷試験より、(1)電気防食の実施によりカソード鉄筋付近でASRによるひび割れが増大する、(2)電気防食を実施しない試験体ではASRによる損傷の程度には関係なく曲げ載荷時の耐荷力は低下しない、(3)電気防食を実施した試験体ではカソード鉄筋の周囲でASRが局部的に進行し、鉄筋とコンクリートの付着強度が低下する、(4)電気防食を実籐した試験体では鉄筋の付着強度の低下により曲げ載荷時の耐荷力が低下する、ことが確認された。<br />Reinforced concrete beams with different water : cement ratios, 0.2 m by 0.3 m by 2 m, were made from the non-reactive river sand and the reactive andesitic coarse aggregate. After 28 days of the curing time, reinforced concrete beams were exposed outdoors, and the cathodic protection current of 50 mA/m^2 was applied to the steel reinforcement of RC beams. The expansion and cracking were monitored for about 3 years in order to investigate whether or not the cathodic protection may really accelerate the alkali-silica reaction of concrete around the steel cathode. After 3 years of the exposure time, the flexural loading test was carried out for ASR damaged RC beams.The main results obtained in this study are as follows ;(1) The concrete cylinders deteriorated due to the occurrence of ASR cracks in spite of the total alkali content of less than 3 kg/m^3 when they were exposed to a natural environment.(2) The cathodic protection current significantly increased the expansion and cracking of the RC beams containing alkali-reactive aggregates.(3) The surface treatment by the epoxy-type coating was not effective in controlling the expansion due to ASR especially when the cathodic protection was applied.(4) The load-bearing capacity in bending of the RC beams did not change independently of the degree of deterioration due to ASR cracks when the cathodic protection was not applied.(5) The load-bearing capacity in bending of the RC beams was 10 to 20 % lower due to the decrease in the bond strength around the steel cathode when the cathodic protection was applied for a long period.<br />研究課題/領域番号:09555134, 研究期間(年度):1997-1998<br />出典：「直流電流作用下のRC構造物におけるアルカリ骨材反応の促進機構に関する実証的研究」研究成果報告書 課題番号09555134 (KAKEN：科学研究費助成事業データベース（国立情報学研究所）) 本文データは著者版報告書より作成
続きを見る
|
||||
| 27.
論文 |
論文
|
鳥居, 和之 ; Torii, Kazuyuki
概要:
鉄筋コンクリート構造物の早期劣化の問題が指摘されて久しいが、厳しい塩分腐食環境下におかれた鉄筋コンクリート構造物では比較的短い期間に何らかの形で鉄筋腐食に伴う劣化・変状が現われてくるのが通常である。鉄筋コンクリート構造物の維持管理や補修法を
…
決定するための検査法には、コンクリート中の鉄筋とかぶりコンクリートの状況を現場にてリアルタイムに把握できることが重要であり、また将来にわたる鉄筋腐食の進行を初期段階にて精度良く予測するには、かぶりコンクリートの塩化物イオン、酸素の透過性および鉄筋に対する保護機能を総合的に判断できる検査法が望まれている。このような観点より、(1)海洋環境下に暴露した鉄筋埋設コンクリート試験体の腐食状況および塩分浸透量を調べることにより、かぶりコンクリートの塩化物イオン透過性と内部鉄筋の腐食との関係について明らかにした。(2)交流インピーダンス法より求めたコンクリートの電気伝導率(比抵抗)と細孔構造との関係を詳細に調べることにより、コンクリートの電気伝導率(比抵抗)から塩化物イオンの透過性や鉄筋に対する保護機能などの性質を推定する方法の有効性について検証した。(3)急速塩化物イオン透過性試験(AASHTO T-227)はかぶりコンクリートの品質や補修材料の性能などの評価が迅速かつ簡単にできるのが特徴であるが。本試験法によるかぶりコンクリートの鉄筋腐食に対する防食性能の評価基準は適用するコンクリートの種類によって相違すると考えられるので、各種コンクリートに対して急速塩化物イオン透過性試験と交流インビーダンス法による電気伝導率(比抵抗)の測定を実施し、両者の関係について明らかにした。以上の結果をふまえて、かぶりコンクリートの鉄筋腐食に対する腐食機能の評価法および急速塩化物イオン透過試験の適用性についての提言を行った。<br />From the results of 5-year exposure test under a marine environment, it was confirmed that the fly ash 30% concrete and the silica fume 10% concrete performed better in corrosive behavior of the steel bar in concrete compared with the normal Portland cement concrete and the blast-furface slag 50% concrete, and that the results of the Rapid Chloride Permeability Test (RCPT,AASHTO T277) gave a reasonable estimate of chloride ion permeability of normal Portland cement concrete in service although the AASHTO T277 test was primarily a conductivity measurement. With the regard to the chloride ion permeability of concretes incorporating mineral admixtures, the results of the RCPT showed that both the surface and the interior of the concretes with mineral admixtures were much less permeable to chloride ions than the corresponding normal Portland cement concrete under all curing and environmental conditions. Furthermore, it was found that there was a good correlation between the charge passed in the RCPT,the initial direct current and the electrical resistance, which also correlated well with the chloride ion penetration depth into the concrete after the RCPT.With the regard to the diffusion coefficient for chloride ions calculated according to the Ficks second law, the coulomb values obtained from the RCPT also correlated well with both the diffusion coefficient for chloride ions and the depth of chloride ion penetration after the exposure to a marine environment.<br />研究課題/領域番号:07650526, 研究期間(年度):1995-1996<br />出典：「交流インピーダンス法によるコンクリートの鉄筋腐食の新しい検査法の開発」研究成果報告書 課題番号07650526(KAKEN：科学研究費助成事業データベース（国立情報学研究所）) 本文データは著者版報告書より作成
続きを見る
|
