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C filler; Surfactant-driven interfacial and microstructural controlNiu, X.*; Elakneswaran, Y.*; Kikuchi, Ryosuke*; Li, A.*; Seralathan, S.*; Hiraki, Yoshihisa; Sato, Junya; Osugi, Takeshi; Kamiyama, Takashi*; Walkley, B.*
Cement and Concrete Research, 200, p.108096_1 - 108096_17, 2026/02
Times Cited Count：2 Percentile：23.63(Construction & Building Technology)Chaerun, R. I.; Sato, Junya; Hiraki, Yoshihisa; Yoshida, Yukihiko; Sato, Tsutomu*; Osugi, Takeshi
Construction and Building Materials, 500, p.144270_1 - 144270_10, 2025/11
Times Cited Count：1 Percentile：0.00(Construction & Building Technology)Alkali-activated materials (AAMs), particularly those derived from metakaolin, have gained significant attention as sustainable binders for hazardous waste immobilisation, owing to their dense microstructure and chemical durability. Their amorphous aluminosilicate framework enables effective encapsulation of hazardous materials and reduces environmental risks. However, maintaining the stability of this amorphous network is challenging, particularly when sodium (Na
)-rich precursors are used, as excess Na) promotes crystallisation and compromises matrix integrity. This study systematically investigates the influence of Na) concentration on the structural stability of metakaolin-based AAMs activated primarily with potassium (K)). The objective is to identify the threshold Na incorporation level that preserves the amorphous structure and maintains chemical stability. Transmission electron microscopy (TEM), Raman spectroscopy, and thermodynamic modelling were employed to examine the structural evolution of K-AAMs across a range of Na:K molar ratios. The results reveal that higher Na:K ratios induce nanopore formation and early crystallisation of Na-rich zeolitic phases, which can reduce matrix stability. In contrast, an optimal Na:K ratio was identified that maintains the amorphous network and preserves the aluminosilicate framework. These findings provide valuable insights into optimising K-AAMs for advanced, durable waste encapsulation technologies.
Niu, X.*; Elakneswaran, Y.*; Li, A.*; Seralathan, S.*; Kikuchi, Ryosuke*; Hiraki, Yoshihisa; Sato, Junya; Osugi, Takeshi; Walkley, B.*
Cement and Concrete Research, 190, p.107814_1 - 107814_17, 2025/04
Times Cited Count：11 Percentile：90.65(Construction & Building Technology)Taniguchi, Takumi; Matsumoto, Saori; Hiraki, Yoshihisa; Sato, Junya; Fujita, Hideki*; Kaneda, Yoshihisa*; Kuroki, Ryoichiro; Osugi, Takeshi
JAEA-Review 2024-059, 20 Pages, 2025/03
JAEA-Review-2024-059.pdf:1.0MB
The basic performance required for solidifying waste into cement, such as fluidity before curing and strength after curing, is expected to be affected by the chemical effects of substances and components contained in the waste. The fluidity before curing and the strength properties after curing are greatly influenced by the curing speed of the cement. We investigated existing knowledge with a focus on chemical substances that affect the curing speed of cement. In this report, chemical substances that affect fluidity are broadly classified into inorganic substances such as (1) anion species, (2) metal elements such as heavy metals, (3) inorganic compounds as cement admixtures, and (4) organic compounds as cement admixtures. Based on the investigation, we actually added chemicals and measured the setting time. As a result, it was found that there are multiple mechanisms contributing to accelerated hardening. We investigated chemical substances that inhibit the curing reaction of cement, and were able to compile information to consider ingredients that are contraindicated in cement curing.
Hiraki, Yoshihisa; Enomoto, Mayu*; Terasawa, Toshiharu*; Imaizumi, Ken*; Kato, Jun; Osugi, Takeshi; Sone, Tomoyuki; Kuroki, Ryoichiro
no journal, ,
Evaluate the maximum temperature of solidified body, when Secondary Waste Produced from Contaminated Water Treatment at Fukushima Daiichi NPP is solidified with cement etc. Simulate various container shapes, and analysis using the radiation transport code and the thermal analysis code was performed. The summary of the test and some of the obtained results are introduced.
Kakuda, Ayaka; Osone, Osamu*; Hiraki, Yoshihisa; Osugi, Takeshi; Sone, Tomoyuki; Kuroki, Ryoichiro; Kudo, Isamu*; Elakneswaran, Y.*; Sato, Tsutomu*
no journal, ,
no abstracts in English
Hiraki, Yoshihisa
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no abstracts in English
Hiraki, Yoshihisa
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no abstracts in English
Hiraki, Yoshihisa; Kakuda, Ayaka; Saito, Toshimitsu*; Sone, Tomoyuki; Elakneswaran, Y.*; Sato, Tsutomu*; Osugi, Takeshi; Kuroki, Ryoichiro
no journal, ,
no abstracts in English
Hiraki, Yoshihisa; Taniguchi, Takumi; Okada, Takashi; Yoshida, Yukihiko; Osugi, Takeshi
no journal, ,
no abstracts in English
Hiraki, Yoshihisa; Sato, Junya; Chaerun, R. I.; Niu, X.*; Kikuchi, Ryosuke*; Elakneswaran, Y.*; Yoshida, Yukihiko; Osugi, Takeshi
no journal, ,
no abstracts in English
Hiraki, Yoshihisa; Terasawa, Toshiharu*; Imaizumi, Ken*; Taniguchi, Takumi; Kato, Jun; Osugi, Takeshi; Sone, Tomoyuki; Nakazawa, Osamu; Kuroki, Ryoichiro
no journal, ,
The relationship between the amount of radionuclide to be solidified and the solidified body temperature was analyzed, when solidify contaminated water management waste at Fukushima Daiichi Nuclear Power Station with cement etc. at low temperature. The analysis code used the radiation transport code and the thermal analysis code. Thus, the limit value by radionuclide concentration during solidification process are evaluated. The summary of the test and some of the obtained results are introduced.
Hiraki, Yoshihisa; Saito, Toshimitsu*; Kakuda, Ayaka; Osugi, Takeshi; Sone, Tomoyuki; Kuroki, Ryoichiro; Kudo, Isamu*; Elakneswaran, Y.*; Sato, Tsutomu*
no journal, ,
no abstracts in English
Hiraki, Yoshihisa; Tabata, Koichi; Taniguchi, Takumi; Kuroki, Ryoichiro; Osugi, Takeshi
no journal, ,
no abstracts in English
Hiraki, Yoshihisa; Sato, Junya; Chaerun, R. I.; Niu, X.*; Elakneswaran, Y.*; Yoshida, Yukihiko; Osugi, Takeshi
no journal, ,
Hiraki, Yoshihisa; Taniguchi, Takumi; Okada, Takashi; Yoshida, Yukihiko; Osugi, Takeshi
no journal, ,
no abstracts in English
Niu, X.*; Elakneswaran, Y.*; Kikuchi, Ryosuke*; Osugi, Takeshi; Sato, Junya; Hiraki, Yoshihisa; Chaerun, R. I.
no journal, ,
In the Primary Containment Vessel (PCV) of the Fukushima Daiichi Nuclear Power Plant, fuel debris and contaminated water form a complex slurry that contains fine particles and colloids mainly composed of iron, barium, and carbonates. In this study, the physicochemical interactions, structural formation behaviour, and the effects on solidification performance were systematically evaluated when these colloids were incorporated into metakaolin-based geopolymers.
Hiraki, Yoshihisa; Kakuda, Ayaka; Saito, Toshimitsu*; Osugi, Takeshi; Sone, Tomoyuki; Kuroki, Ryoichiro; Elakneswaran, Y.*; Sato, Tsutomu*
no journal, ,
no abstracts in English
Kikuchi, Ryosuke*; Takeuchi, Nozomi*; Elakneswaran, Y.*; Niu, X.*; Osugi, Takeshi; Sato, Junya; Hiraki, Yoshihisa; Chaerun, R. I.
no journal, ,
Technologies are required to stabilise and solidify fuel debris and contaminated water present inside the Primary Containment Vessel (PCV) of the Fukushima Daiichi Nuclear Power Plant. In this study, metakaolin, a representative reactive filler, was investigated by comparing the specifications and properties of commercially available products before and after hardening. In addition, with consideration of a stable supply of raw materials, domestically produced metakaolin was manufactured and its properties were systematically evaluated.
Sato, Tsutomu*; Islam, C.*; Elakneswaran, Y.*; Hiraki, Yoshihisa; Osugi, Takeshi; Sone, Tomoyuki; Kuroki, Ryoichiro; Provis, J.*
no journal, ,
no abstracts in English
