Research activity information

• Impacts of Fly-Ash-Shell-Blocks on pH and Nutrient Environments in Seawater
  Kento FUKASE; Takeshi YOSHIMURA; Hiroyuki MIZUTA; Yoshiko HIEI; Shigeo SUNAGA; Takeshi YAMAMOTO; Taku OTSUKA; Yuka MORINAGA; Takuya KOBAYASHI
  Journal of Japan Society on Water Environment, 48, 77, 87, Japan Society on Water Environment, 2025
  Scientific journal
• Delayed Absorption Superabsorbent Polymer for Strength Development in Concrete
  Yuka Morinaga; Yuya Akao; Daisuke Fukuda; Yogarajah Elakneswaran
  Materials, 15, 8, 2727, 2727, MDPI AG, 07 Apr. 2022
  Scientific journal, Superabsorbent polymers (SAPs) are used as internal curing agents in cementitious materials, which reduce autogenous shrinkage in concrete as they have a low water-to-cement ratios and improve the freeze–thaw resistance. However, the compressive strength of concrete may also be reduced due to additional voids in the hydrated cement matrix. In this study, we fabricated a delayed absorption type of SAP (I-SAP) composed of cross-linked modified acrylate and studied its absorption characteristics and effect on compressive strength after 28 days. Furthermore, the effect of curing conditions on the strength of concrete and hydrated cement paste with SAP were investigated. The absorption capacity of I-SAP in the synthetic pore solution and deionised water was examined and compared with that of a conventional SAP, and the former was absorbed more by I-SAP. The results revealed that the compressive strength of concrete increased with the addition of I-SAP, particularly with the curing condition of 60% RH. Although the compressive strength of hydrated cement paste with I-SAP reduced in water or sealed curing conditions, no loss of strength in the paste cured at 60% RH was seen. The cement matrix densification due to hydration of belite around the SAP surface is the main mechanism for strength development in concrete cured at sealed and 60% RH. However, the voids formed by SAP control the compressive strength of hydrated paste.
• Measurements of Small-angle X-ray Scattering for Cement Paste Samples with Light Water and Heavy Water
  Kaoru Y. Hara; Yuka Morinaga; Yuya Yoda; Masato Ohnuma
  2021 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC), IEEE, 16 Oct. 2021
  International conference proceedings
• Effects of a New Type of Shrinkage-Reducing Agent on Concrete Properties
  Mari Masanaga; Tsuyoshi Hirata; Hirokatsu Kawakami; Yuka Morinaga; Toyoharu Nawa; Yogarajah Elakneswaran
  Materials, 13, 13, 3018, 3018, MDPI AG, 06 Jul. 2020
  Scientific journal, Shrinkage-reducing agents have been developed to mitigate shrinkage and to control cracks in concrete. This study aims to evaluate the impact of a newly developed shrinkage-reducing agent (N-SRA) on concrete properties and to compare its properties with a conventional shrinkage-reducing agent (C-SRA). The hydration rate, compressive strength, splitting tensile strength, shrinkage, occurrence of cracking, and freezing and thawing were investigated. N-SRA showed higher surface tension than C-SRA and reduced shrinkage to the same degree as C-SRA with half the dosage of C-SRA. The addition of N-SRA or C-SRA did not influence the early compressive strength but slightly reduced splitting tensile strength at seven days. Concrete with N-SRA showed higher compressive strength at 28 days than those of concrete with C-SRA or without SRA. Furthermore, concrete with N-SRA extended the period for the occurrence of shrinkage cracking under restrained conditions. It was found that N-SRA provided excellent freezing and thawing resistance because of the formation of good air voids, while C-SRA demonstrated inefficient behaviour in such an environment.
• Characteristics of Ferrite-Rich Portland Cement: Comparison With Ordinary Portland Cement
  Yogarajah Elakneswaran; Natsumi Noguchi; Kazuki Matumoto; Yuka Morinaga; Takashi Chabayashi; Hiroyoshi Kato; Toyoharu Nawa
  Frontiers in Materials, 6, Frontiers Media SA, 01 May 2019
  Scientific journal
• THE EFFECT OF SEEDING OF SYNTHETIC C-S-H WITH DIFFERENT C/S ON EARLY HYDRATION REACTION OF ALITE
  Yumetoki ABE; Yuka MORINAGA; Satoshi YOSHIDA; Toyoharu NAWA
  Cement Science and Concrete Technology, 72, 1, 10, 17, Japan Cement Association, 29 Mar. 2019
  Scientific journal
• Sulphate attack in slag-blended cementitious materials hydrated with sodium sulphate
  Li Chuang; Tomohiro Kajio; Eiji Owaki; Yuka Morinaga; Yogarajah Elakeswaran; Toyoharu Nawa
  Sustainable Construction Materials and Technologies, 2, International Committee of the SCMT conferences, 2019
  English, International conference proceedings
• The effect of seeding of synthesized C-S-H with different C/S on early hydration reaction of alite
  Yumetoki Abe; Yuka Morinaga; Toyoharu Nawa; Yogarajah Elakneswaran
  Sustainable Construction Materials and Technologies, 2, International Committee of the SCMT conferences, 2019
  English, International conference proceedings
• Influence of portlandite on Pyrex glass dissolution and the formation of alkali‐silica chemical reaction products
  Natsumi Noguchi; Yuka Morinaga; Tomohiro Kajio; Elakneswaran Yogarajah; Toyoharu Nawa
  Journal of the American Ceramic Society, 101, 10, 4549, 4559, Wiley, 02 May 2018
  Scientific journal
• Impact of portlandite on alkali-silica reaction of pyrex glass and blastfurnace slag aggregate
  N. Noguchi; T. Kajio; Y. Morinaga; Y. Elakneswaran; T. Nawa; T. Ayan
  6th International Conference on Durability of Concrete Structures, ICDCS 2018, 267, 272, 2018
  International conference proceedings
• Comparison of alkali-silica chemical reaction of reactive glass and chert aggregate
  Y. Morinaga; E. Yogarajah; T. Nawa; Lalita Yongchaitrakul; E. Iwatsuki
  6th International Conference on Durability of Concrete Structures, ICDCS 2018, 248, 255, 2018, [Peer-reviewed], [Lead author]
  International conference proceedings
• U-Phase[(CaO)x (Al2O3) (SO3)y(Na2O)z:nH2O] in Hydrating Cement with Sodium Sulfate
  Yuka Morinaga; Tomohiro Kajio; Elakneswaran Yogarajah; Toyoharu Nawa; Eiji Owaki
  International Con ference on Advances in Construction Materials and Systems, 3, 547, 556, Sep. 2017, [Peer-reviewed], [Lead author]
  International conference proceedings
• THE ROLE OF PORTLANDITE ON THE HYDRATION OF C₃A
  Tomohiro KAJIO; Yuka MORINAGA; Yogarajah ELAKNESWARAN; Toyoharu NAWA
  Cement Science and Concrete Technology, 71, 1, 40, 47, Japan Cement Association, 2017
  Scientific journal
• IMPACT OF BFS ADDITION ON EXPANSION AND SHIRINKAGE OF SLAG BLENDED CEMENT PASTE DURING FREEZING AND MELTING PROCESSES
  Yuka MORINAGA; Ryo HORIE; Toyoharu NAWA
  Cement Science and Concrete Technology, 71, 1, 331, 338, Japan Cement Association, 2017
  Scientific journal
• THE INFLUENCE OF CALCIUM CHLORIDE IN EARLY HYDRATION REACTION OF ALITE
  Yumetoki ABE; Tatsuya OYAMA; Yuka MORINAGA; Toyoharu NAWA
  Cement Science and Concrete Technology, 71, 1, 2, 9, Japan Cement Association, 2017
  Scientific journal
• Mesoscopic model of volume changes due to moisture changes in hardend cement paste
  Yuka Morinaga; Toyoharu Nawa
  Sustainable Construction Materials and Technologies, 2016-, International Committee of the SCMT conferences, 2016
  English, International conference proceedings
• IMPACT OF Ca/Si AND Al ADDITION RATIO ON STRUCTURE AND SURFACE CHARGE OF CALCIUM-（ALUMINO）SILICATE-HYDRATE
  Hajime KOBAYASHI; Satoshi YOSHIDA; Yuka MORINAGA; Toyoharu NAWA
  Cement Science and Concrete Technology, 70, 1, 77, 84, Japan Cement Association, 2016
  Scientific journal
• IMPACT OF W/C ON THE INTERNAL STRESS IN HARDENED CEMENT PASTE DURING FREEZING AND THAWING
  Ryo HORIE; Yuka MORINAGA; Toyoharu NAWA
  Cement Science and Concrete Technology, 70, 1, 16, 23, Japan Cement Association, 2016
  Scientific journal
• CLARIFICATION OF ADSORPTION AND SORPTION MECHANISM OF POLYCARBOXYLATE ACID BY CALCIUM-ALUMINIUM LAYERED DOUBLE HYDROXIDES
  Masaaki MORI; Takato YAMAMOTO; Yuka MORINAGA; Toyoharu NAWA
  Cement Science and Concrete Technology, 70, 1, 47, 53, Japan Cement Association, 2016
  Scientific journal
• ANALYSIS OF C3A HYDRATION IN C3A-Gypsum-Ca（OH）2 SYSTEM BY COMBINING XRD/RIETVELD AND 27Al MAS-NMR ANALYSIS
  Tomohiro KAJIO; Kohei UEDA; Toyoharu NAWA; Yuka Morinaga
  Cement Science and Concrete Technology, 70, 1, 111, 118, Japan Cement Association, 2016
  Scientific journal
• THE EFFECT OF SUCROSE ON THE HYDRATION OF ALITE AND INVESTIGATION OF HYDRATION MECHANISM
  Tatsuya OYAMA; Toyoharu NAWA; Yuka MORINAGA; Junbum PARK
  Cement Science and Concrete Technology, 70, 1, 24, 31, Japan Cement Association, 2016
  Scientific journal
• ANALYSIS OF C₃A HYDRATION WITH APPLICATION OF SURFACE COMPLEXATION MODEL
  Kohei UEDA; Yuka MORINAGA; Toyoharu NAWA; Aoi HATAKEYAMA
  Cement Science and Concrete Technology, 69, 1, 29, 36, Japan Cement Association, 2015
  Scientific journal
• QUANTITATIVE HYDRATED SILICATE MONOMER IN HYDRATION OF ALITE AND CONSIDERATION OF CEMENT HYDRATION MECHANISM
  Toyoharu NAWA; Tomotaka AWAMURA; Junbum PARK; Yuka MORINAGA
  Cement Science and Concrete Technology, 69, 1, 2, 9, Japan Cement Association, 2015
  Scientific journal
• STUDY ON INFLUENCE OF RELATIVE HUMDITY ON C₃S IN WHITE CEMENT BASED ON THERMODYNAMIC CONCEPT
  Yuka MORINAGA; Tomotaka AWAMURA; Aoi HATAKEYAMA; Toyoharu NAWA
  Cement Science and Concrete Technology, 68, 1, 22, 29, Japan Cement Association, 2014
  Scientific journal

• 原子力発電で発生する混合廃棄物の安全性評価指標の構築に向けた基礎的研究
  科学研究費助成事業
  01 Apr. 2023 - 31 Mar. 2026
  渡辺 直子; 森永 祐加; 植松 慎一郎; 小崎 完; 湊 大輔
  商用原子力発電所の廃止措置の進展に伴い、解体廃棄物に加えて、発電所に保管されている運転廃棄物の処理・処分が必要となる。これらの廃棄物には、放射性核種に加えて、鉛、六価クロムなどの重金属、PCB、アスベスト、高濃度の塩など環境影響物質が混在する混合廃棄物が含まれるが、現状では混合廃棄物の処理・処分のルートは確定していない。本研究では、放射性廃棄物全体の中での各環境影響物質の潜在的危険度を把握した上で、優先順位の高い代表的な環境汚染物質を抽出してセメントによる固定化やバリア材による保持など、相互作用のメカニズムに関する基礎研究を行う。
  令和5年度には、高濃度の塩を含むセメント固化体に着目し、放射性核種のセメントによる固定可能を評価する手法を確立した。その手法を用いて、高濃度の硫酸ナトリウムを含有するセメント固化体からのCs-137の脱離挙動を評価し、セメントの微細構造との関係正から検討した。その結果、Cs-137を未水和のセメントと混錬しセメントの水和反応が進行する過程にCs-137が共存することで、水和後のセメントに収着させる場合よりも収着分配係数が一桁大きくなること、Cs-137の収着における硫酸ナトリウムによる影響は顕著ではないことがわかった。
  今後は、核種及び有害物質の種類を増やし、セメントによる核種、有害物の固定化のメカニズムについて評価するとともに、合理的・効果的な安全性評価指標について検討する。
  日本学術振興会, 基盤研究(C), 北海道大学, 23K04626