Researcher Database

KAWAAI, Keiyu

FacultyGraduate School of Science and Engineering Civil and Environmental Engineering
PositionSenior Assistant Professor
Last Updated :2020/05/12

Researcher Profile and Settings

Profile and Settings

Name

  • Name

    KAWAAI, Keiyu

Profile & Settings

  • アバター画像URI

    https://researchmap.jp/7000014939/avatar.jpg

Education, Etc.

Education

  • 2009/08 - 2013/09
  • 2004/04 - 2006/03
  • 2000/04 - 2004/03

Degree

  • PhD

その他基本情報

Association Memberships

  • RILEM
  • THE SOCIETY OF MATERIALS SCIENCE, JAPAN
  • JAPAN SOCIETY OF CIVIL ENGINEERS
  • JAPAN CONCRETE INSTITUTE

Committee Memberships

  • 2018/04 - Today
  • 2017/10 - Today
  • 2017/07 - Today
  • 2016/12 - 2018/04
  • 2016/04 - 2018/04
  • 2016/04 - 2018/04
  • 2015/04 - 2017/03
  • 2014/04 - 2016/03
  • 2013/11 - 2015/03

Academic & Professional Experience

  • 2019/04 - Today, Graduate School of Science and Engineering, Engineering for Production and Environment, Ehime University
  • 2016/10 - 2019/03
  • 2016/10 - 2019/03, Graduate School of Science and Engineering, Engineering for Production and Environment, Ehime University
  • 2013/10 - 2016/09, Graduate School of Science and Engineering, Engineering for Production and Environment, Ehime University
  • 2015/06 - 2015/12
  • 2013/07 - 2013/09
  • 2006/04 - 2009/07

Research Activities

Book, papers, etc

Published Papers

  • 2020/09, [Refereed], 0950-0618, 10.1016/j.conbuildmat.2020.119265
  • Corrosion resistance of steel bars in mortar mixtures mixed with organic matter, microbial or other, K. Kawaai, T. Nishida, A. Saito, I. Ujike, S. Fujioka, Cement and Concrete Research, Cement and Concrete Research, 2019/10, 0008-8846, 10.1016/j.cemconres.2019.105822
  • 2019/07, [Refereed]
  • Corrosion Current Density of Macrocell of Horizontal Steel Bars in Reinforced Concrete Column Specimen, N. Sandra, K. Kawaai, I. Ujike, International Journal of Geomate, International Journal of Geomate, 2019, [Refereed]
  • Application of bio-based material for concrete repair: case study leakage on parallel concrete slab, Prima Yane Putri, Isao Ujike, Keiyu Kawaai, MATEC Web of Conferences 258:01013, MATEC Web of Conferences 258:01013, 2019/01, [Refereed]
  • Effects of bleeding on corrosion of horizontal steel bars in reinforced concrete column specimen, International Journal of Technology, 2019, [Refereed]
  • ALGINATE-BACILLUS SUBTILIS BASED REPAIR MATERIALS FOR SEALING CRACKS IN CONCRETE, Masahiko Ide, Keiyuu Kawaai, Isao Ujike, 2018/10, [Refereed]
  • EFFECT OF INITIAL CURING ON CORROSION BEHEAVIOR OF STEEL BARS IN FA CONCRETE UNDER DRY AND WET ACTIONS, Wakako Sugino, Keiyuu Kawaai, Isao Ujike, 2018/10, [Refereed]
  • CORROSION PROPERTIES OF HORIZONTAL STEEL BARS IN CONCRETE COLUMN SPECIMENS CAST WITH COPPER SLAG FINE AGGREGATE, N. Sandra, K. Kawaai, I. Ujike, 4th International Conference on Service Life Design for Infrastructures, 4th International Conference on Service Life Design for Infrastructures, 2018/08, [Refereed]
  • Influence of bleeding on modification of pore structure and carbonation-induced corrosion formation, Willick Nsama, Isao Ujike, Keiyu Kawaai, Yuto Kubo, Nevy Sandra, 4th International Conference on Service Life Design for Infrastructures, 4th International Conference on Service Life Design for Infrastructures, 2018/08, [Refereed]
  • APPLICABILITY OF BIO-BASED MATERIALS TO REPAIR WATER LEAKAGE OF CONCRETE, Prima Yane PUTRI, Isao UJIKE, Keiyu KAWAAI, 40th Japan Concrete Institute Annual Convention, 40th Japan Concrete Institute Annual Convention, 2018/07, [Refereed]
  • CATHODIC POLARIZATION PROPERTIES OF STEEL BARS IN CONCRETE MIXED WITH AEROBIC MICROORGANISM, K. Kawaai, I. Ujike, S. Fujioka, T. Nishida, A. Saito, Final Conference of RILEM TC 253-MCI, Final Conference of RILEM TC 253-MCI, 2018/06, [Refereed]
  • Restrained early age shrinkage at the vertical interface between fresh cementitious mixtures and hardened substrates Part-II, K. Kawaai, O.K.C. Gary, International Journal of Engineering Research and Applications, International Journal of Engineering Research and Applications, 2018, [Refereed]
  • Restrained early age shrinkage at the vertical interface between fresh cementitious mixtures and hardened substrates Part-I, K.Kawaai, O.K.C. Gary, International Journal of Engineering Research and Applications, International Journal of Engineering Research and Applications, 2018, [Refereed]
  • Abundance and size of microplastics in a coastal sea: Comparison among bottom sediment, beach sediment, and surface water, N. Sagawa, K. Kawaai, H. Hinata, Marine Pollution Bulletin, Marine Pollution Bulletin, 2018, [Refereed]
  • 2017/10, [Refereed]
  • 2017/08, [Refereed], 10.2472/jsms.66.601
  • 2017/08, [Refereed], 10.2472/jsms.66.615
  • 2017/08, [Refereed], 10.2472/jsms.66.608
  • INFLUENCE OF BLEEDING ON VARIATIONS OF PERMEABILITY IN CONCRETE COLUMN SPECIMENS, KAWAAI Keiyu, 2017/08, [Refereed]
  • 2017/07, [Refereed]
  • 2017/07, [Refereed], 10.2473/journalofmmij.133.132
  • 2017/07, [Refereed]
  • Influence of the type of dry yeast on precipitation rate of calcium carbonate in bio-based repair materials, ICBBM ECOGRAFI, 2017/06, [Refereed]
  • Alginate capsules encapsulating aerobic and anaerobic microorganism for repairing cracks in concrete, 6th International Conference on Self-Healing Materials, 6th International Conference on Self-Healing Materials, 2017/06, [Refereed]
  • 2017, [Refereed]
  • Enhancement of corrosion resistance in mortar using aerobic bacillus subtilis, K. Kawaai, I. Ujike, P.Y. Putri, HealCon, HealCon, 2016/11, [Refereed]
  • 2016/10, [Refereed]
  • 2016/10
  • Influence of Bleeding on Durability of Horizontal Steel Bars in RC Column Specimen, K. Kawaai, I. Ujike, Fifth International Symposium on Life-Cycle Civil Engineering, Fifth International Symposium on Life-Cycle Civil Engineering, 2016/10, [Refereed]
  • A study on the factors affecting electro-migration characteristic of chloride ion in concrete, ASEA SEC, International Conference, 2016/09, [Refereed]
  • 2016/07, [Refereed]
  • 2016/07, [Refereed]
  • A Novel Method in Enhancing Corrosion Resistance in Concrete Using Aerobic Bacillus Subtilis, K. Kawaai, T. Nishida, A. Saito, I. Ujike, International Symposium on Concrete and Structures for Next Generation: Ikeda & Otsuki Symposium (IOS 2016), International Symposium on Concrete and Structures for Next Generation: Ikeda & Otsuki Symposium (IOS 2016), 2016/05, [Refereed]
  • Effect of Temperature on Precipitation Rate of Calcium Carbonate Produced Through Microbial Metabolic Process of Bio Materials, Prima, Y. P, Kawaai, K, Ujike, I, Journal of Civil Engineering Science and Application, Journal of Civil Engineering Science and Application, 2016, [Refereed]
  • 2016, [Refereed]
  • Effects of Internal Cracking and Drying Shrinkage on Corrosion Processes of RC Beam Specimen, K. Kawaai, I. Ujike, I. Nakai, CONCREEP 10, doi: 10.1061/9780784479346.057, CONCREEP 10, doi: 10.1061/9780784479346.057, 2015/09, [Refereed], 10.1061/9780784479346.057
  • ESTIMATION METHOD FOR DURABILITY PERFORMANCES IN COVER CONCRETE BY IN-SITU AIR PERMEABILITY TESTS, K. Kawaai, I. Ujike, The Fifth International Conference on Construction Materials: Performance, Innovations and Structural Implications, The Fifth International Conference on Construction Materials: Performance, Innovations and Structural Implications, 2015/08, [Refereed]
  • CARBONATION AT VERTICAL INTERFACES FORMED BETWEEN FRESHLY CAST CEMENTITIOUS MIXTURES AND HARDENED CONCRETE SUBSTRATES, K. Kawaai, A. Annapareddy, K.C.G. Ong, C.T. Tam, 40th Conference on Our World Concrete & Structures, 40th Conference on Our World Concrete & Structures, 2015/08, [Refereed]
  • 炭酸カルシウムの析出速度及び析出量に及ぼす諸要因に関する研究, 山本沙也, 久保郁貴, 河合慶有, 氏家勲, コンクリート工学年次論文集(CD-ROM), コンクリート工学年次論文集(CD-ROM), 2015/06, [Refereed], 1347-4111
  • 銅スラグ細骨材とフライアッシュを使用した乾燥収縮ひび割れ抑制コンクリートの開発, 仲井一平, 高本直樹, 河合慶有, 氏家勲, コンクリート工学年次論文集(CD-ROM), コンクリート工学年次論文集(CD-ROM), 2015/06, [Refereed], 1347-4111
  • 乾湿繰り返し作用を受けるフライアッシュコンクリートの鉄筋腐食性状に及ぼす初期養生および水結合材比の影響, 門屋朱里, 春日翔平, 河合慶有, 氏家勲, コンクリート工学年次論文集(CD-ROM), コンクリート工学年次論文集(CD-ROM), 2015/06, [Refereed], 1347-4111
  • Effect of curing condition on air permeability coefficient measured by in-situ test method, K. Kawaai, I. Ujike, S. Kunikata, S. Okazaki, Life-Cycle of Structural Systems Design, Assessment, Maintenance and Management, CRC press, Life-Cycle of Structural Systems Design, Assessment, Maintenance and Management, CRC press, 2014/10, [Refereed]
  • SHORT-TERM AND LONG-TERM SOLUTIONS USING FLY ASH FOR SUSTAINABLE DEVELOPMENT IN CONCRETE CONSTRUCTION INDUSTRY, K. Kawaai, I. Ujike, S. Kasuga, H. Miyake, Proceedings of Workshop on Utilization of Waste Materials, Manila, Proceedings of Workshop on Utilization of Waste Materials, Manila, 2014/08, [Refereed]
  • 2014/07, [Refereed]
  • 2014/07, [Refereed]
  • 2014, [Refereed]
  • DURABILITY DESIGN OF TYPICAL DFD (DESIGN FOR DISASSEMBLY) COMPONENTS FOR A TROPICAL ENVIRONMENT, KEIYU KAWAAI, National University of Singapore, National University of Singapore, 2013/09, [Refereed]
  • SIZE-EFFECT OF EARLY AGE SHRINKAGE AT THE INTERFACE BETWEEN FRESH CEMENTITIOUS MIXTURES AND HARDENED CONCRETE SUBSTRATE, K.C.G. Ong, K. Kawaai, C.T. Tam, Sze-Dai Pang, 37rd Our World in Concrete and Structures, 37rd Our World in Concrete and Structures, 2013/08, [Refereed]
  • 2008/08, [Refereed]
  • 2006/08, [Refereed]
  • 2004

Books etc

  • 2018/10

Conference Activities & Talks

  • 2018/07, 招待有り
  • 2017/07, 招待有り
  • 2017/05
  • 2017/05
  • 2016/10, 招待有り
  • 2016/06, 招待有り
  • 2016/05
  • 2016/05
  • 2016/05
  • 2016/05
  • 2016/05
  • 2016/05
  • 2015/05
  • 2015/05
  • 2015/05
  • 2015/05
  • 2015/05
  • 2015/05
  • 2015/05
  • 2015/05
  • コンクリートの初期養生及び材齢が電気泳動試験に及ぼす影響, 河合慶有, 氏家勲, 國方翔太, 土木学会年次学術講演会講演概要集(CD-ROM), 2014/08
  • 2014/05
  • 2014/05
  • 2014/05
  • 2014/05
  • 2014/05
  • 電着工法におけるひび割れ深部での電着物析出阻害の機構解明およびその改善, 鈴木一平, 大即信明, 西田孝弘, 河合慶有, セメント技術大会講演要旨, 2006/05
  • 鉄筋コンクリートに対する適切な電気防食回路の設計に関する基礎的研究, 河合慶有, 大即信明, 西田孝弘, 鄭仁沢, セメント技術大会講演要旨, 2004/04

Misc

  • Effects of bleeding on the corrosion of horizontal steel bars in reinforced concrete column specimens, Nevy Sandra, Keiyu Kawaai, Isao Ujike, Ippei Nakai, Willick Nsama, International Journal of Technology, International Journal of Technology, 10, 741, 752, 2019/07, 2086-9614, 10.14716/ijtech.v10i4.2503, https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85070020017&origin=inward, © IJTech 2019. The durability of reinforced concrete has proven to be predominantly influenced by its resistance against the ingress of harmful substances such as chloride ions, carbon dioxide and moisture. The corrosion of steel bars which occurs especially in marine environments is likely to be severe, depending on the availability of oxygen and the moisture consumed by cathodic reactions. This study aims to investigate the effects of bleeding on the corrosion of horizontal steel bars placed in reinforced concrete column specimens. The issue was examined through electro-chemical tests, including half-cell potential, polarization resistance and corrosion current density, conducted using specimens in which corrosion was induced via dry and wet (NaCl 10%) cycles. The presence or absence of copper slag fine aggregate and fly ash replacement was employed as an experimental parameter. The results suggest that the corrosion of horizontal steel bars in the upper part of the column concrete specimens was adversely affected, even in the case of OPC specimens with relatively lower bleeding water. This was attributed to lower resistance against the ingress of corrosive substances, especially in such locations. In the case of fly ash mixtures, resistance to corrosion was significantly improved owing to lower oxygen permeability of less than 1.0×10-11mol/cm2/sec, measured via the cathodic polarization technique. The replacement of fly ash is effective in facilitating more uniform quality in the column specimens due to a lower level of bleeding water and higher resistance to segregation and pozzolanic reactions.
  • Electrical Resistance Tomography for Assessing Water Movement in Cracked Cementitious Mixtures, Keiyu Kawaai, Isao Ujike, MATEC Web of Conferences, MATEC Web of Conferences, 199, 2018/10, 10.1051/matecconf/201819911016, https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85056623881&origin=inward, © 2018 The Authors, published by EDP Sciences. Electrical resistance tomography (ERT) has been studied for visualizing variations of conductivity in concrete specimens. In recent years, unsaturated water flow through pores formed in concrete has been intensively examined though ERT systems to visualize the permeation front that gradually changes with elapsed time. This study examines water movement through internal cracks which are typically not observed on the surface of mortar or concrete specimens via ERT systems. The results indicate the gradual increase of saturated region owing to the ingress of water through cracked surface up to 120 hours. And, the region with higher conductivity estimated in uncracked parts is evidently in good agreement with higher moisture content measured by moisture meter on the split surface. In addition, the presence of crack in concrete specimen subjected to water ingress is clearly visualized via ERT images owing to rapid water movement in cracked zones. This study has provided the important insight that the ingress and the movement of water through pores and cracks formed in cementitious mixtures could be assessed via electrical measurements.
  • Influence of bleeding on durability of horizontal steel bars in RC column specimen, K. Kawaai, I. Ujike, Life-Cycle of Engineering Systems: Emphasis on Sustainable Civil Infrastructure - 5th International Symposium on Life-Cycle Engineering, IALCCE 2016, Life-Cycle of Engineering Systems: Emphasis on Sustainable Civil Infrastructure - 5th International Symposium on Life-Cycle Engineering, IALCCE 2016, 839, 846, 2017/01, https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85018635755&origin=inward, © 2017 Taylor & Francis Group, London. This study reports on the influence of bleeding on the durability of reinforced concrete, especially horizontally placed steel bars in RC column specimens. This was examined through the use of insitu air permeability tests and electro-chemical tests. The results showed that air permeability coefficients measured in the upper parts of column specimen were relatively higher when the specimens were dried under room conditions, which was dependent on bleeding rate. Although the durability of horizontal steel bars was aggravated by bleeding in a form of segregation, which was confirmed by larger corrosion current density caused by chloride attack through dry and wet cycles, the adverse effect on the durability of horizontal steel bars was less prominent in fly ash mixtures tested in this study.
  • Study on detection method of defects in coveredconcrete using electrical resistivity measurement, Keiyu Kawaai, Isao Ujike, Hiroshi Okuno, ISEC 2017 - 9th International Structural Engineering and Construction Conference: Resilient Structures and Sustainable Construction, ISEC 2017 - 9th International Structural Engineering and Construction Conference: Resilient Structures and Sustainable Construction, 2017/01, https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85027878487&origin=inward, Copyright © 2017 ISEC Press. This study reports on a fundamental study on the investigation of electrical resistivity measurements for detecting internal defects or damages, which aims at developing Electrical Resistance Tomography techniques based on electrical resistivity distribution measured via Wenner method. In particular, this study examined the changes of resistivity upon the presence of damages in the bottom of concrete specimens which mirror internal cracking not visually observed on the concrete surface in typical reinforced concrete structure. For the experimental investigation, ten electrodes comprising stainless steel and electric conductive epoxy were partially embedded on the surface of prism concrete specimen. Then, electrical resistivity was measured via Wenner method using four electrodes selected among the electrodes placed 20 mm apart each other. In addition, analytical investigation simulating the influence of internal damages on current flow and measured voltage or potential was carried out by FEM analysis. As a result, electrical resistivity increased depending on the depth of slits with 1 mm width, which was sawed at the bottom of the specimen. This could be attributed to the influence of the damages on the current flow and equipotential planes, thus suggesting that there is a good possibility that internal damages can be detected based on the changes and the distributions of the electrical resistivity.
  • Influence of different concentration of tris buffer solution on calcium carbonate precipitation in bio-based repair materials, Prima Yane Putri, Keiyu Kawaai, Isao Ujike, Hiroshi Okuno, International Journal on Advanced Science, Engineering and Information Technology, International Journal on Advanced Science, Engineering and Information Technology, 7, 1879, 1885, 2017/01, 2088-5334, 10.18517/ijaseit.7.5.3452, https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85032692032&origin=inward, This research examined differences in the concentration of Tris buffer solution on calcium carbonate precipitation in biobased repair materials. Four concentrations of Tris buffer solution were chosen based on previous research with initial pH 8.0 and 9.0. Initial experiments demonstrated that the concentration and pH of Tris buffer solution had an influence on the amount of precipitation of calcium carbonate. X-Ray Diffraction (XRD) analysis elucidated the morphological and structural differences of the calcium carbonate crystal, including calcite and vaterite. They are the prominent forms of CaCO3 detected based on results obtained by according to FT-IR analysis. The result further explains the effectiveness of Tris buffer concentration.
  • 571, 578, 2016, https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85015053426&origin=inward
  • Effect of curing condition on air permeability coefficient measured by in-situ test method, K. Kawaai, I. Ujike, S. Kunikata, S. Okazaki, Life-Cycle of Structural Systems: Design, Assessment, Maintenance and Management - Proceedings of the 4th International Symposium on Life-Cycle Civil Engineering, IALCCE 2014, Life-Cycle of Structural Systems: Design, Assessment, Maintenance and Management - Proceedings of the 4th International Symposium on Life-Cycle Civil Engineering, IALCCE 2014, 1207, 1214, 2015/01, https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84941243257&origin=inward, © 2015 Taylor & Francis Group, London. This paper presents the investigation on an in-situ assessment technique for durability performances of cover concrete based on the relationship between air permeability coefficients and moisture content. First, an assessment technique for the quality of cover concrete using insitu air permeability tests in conjunction with moisture content measurements was examined. Durability performances of concrete specimens subjected to different curing conditions at an early age were subsequently studied via accelerated tests. Finally, this study exemplified the application of the assessment technique to existing RC structure.

Other Research Activities

Patents

  • 特願2016-087837, 特開2017-197393

Awards & Honors

  • 2018/03
  • 2013/11
  • 2009/08

Research Grants & Projects

  • Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B), Evaluation techniques on corrosion resistance based on oxygen permeability
  • Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (A), Effect of self-healing in concrete and an assessment technique based on corrosion resistance
  • Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B), Study on practical application of repair method of concrete crack using microbial metabolism, Ujike Isao, The filler made of calcium carbonate precipitated by the reaction of carbon dioxide with a calcium source due to the metabolism of microorganisms is called bio-grout. For practical application of repair method by bio-grout, the purpose of this research is to find out the conditions of high precipitation rate of calcium carbonate and to study the method of filling in the places where cracks and water leaks. Although the precipitation rate of calcium carbonate changes depending on the composition of bio-grout and its concentration and temperature, It became clear that that calcium carbonate can maintain a high precipitation rate when the pH of bio-grout does not fall below 7.5 after 24 hours by properly adjusting the alkaline buffer action. Moreover, water leakage can be stopped by injecting bio-grout repeatedly into a crack.
  • Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B), Estimation method for durability performance in cover concrete adversely affected by segregation, Kawaai Keiyu, This study examined the effect of heterogeneity of cover concrete caused by segregation on the resistance against ingress of substances. Air permeability coefficients tended to increase in upper parts of column specimens cast with OPC mixture with typical bleeding water. Based on the results of air permeability and moisture content obtained up to the age of 180 days of monitoring, this study showed that the durability estimation technique based on the relationship between two variables can be applied to assess the heterogeneity such as porous structures formed owing to bleeding water in a form of segregation in column specimen. On the other hand, the ingress of chloride ions tended to increase in those regions affected by bleeding water, which partly contribute to higher microcell corrosion current density. It should be noted that total corrosion current density was likely to increase with higher rate of oxygen permeability measured via cathodic polarization in this study.

Activity track record

Educational activities

Course in charge

  • 2019, the first semester, under graduate, 物理学入門
  • 2019, the first semester, under graduate, 物理学入門
  • 2019, the first semester, under graduate, 建設倫理
  • 2019, the first semester, under graduate, 構造力学Ⅰ及び同演習
  • 2019, the first semester, under graduate, 建設材料学

論文指導(B07)

  • 2017, 4, 3, 1, 2


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