Bentonite group

Purpose: To deeply discuss the latest research among young researchers who can trust each other, and to create a joint research team (system) by leveraging each individual's strengths.

Initiators: Hailong Wang, Hiroyuki Kyogawa, Yasutaka Watanabe

Launch date: February 21, 2021

Contact: h.wang📧civil.t.u-tokyo.ac.jp (Hailong Wang  📧=@)

Study group members:

Hiroyuki Kyogawa Assoc. Prof. Nagoya Institute of Technology

Yasutaka Watanabe Chief Researcher Central Research Institute of Electric Power Industry

Hailong Wang Assoc. Prof. The University of Tokyo

Shinya Tachibana Prof. Kobe University

Ema Yoshikawa Chief Researcher Central Research Institute of Electric Power Industry

Daichi Ito Lecturer Ibaraki University

Ruan Kunlin Assist. Prof. Waseda University

Tokio Morimoto Assis. Prof. The University of Tokyo

Yusuke Takayama Assoc. Prof. Kobe University

Research Exchange with Prof. Martand Singh of the Norwegian University of Science and Technology 

We held a research exchange with Prof. Martand Singh of the Norwegian University of Science and Technology, who was visiting Japan at the invitation of Prof. Kyokawa of Nagoya Institute of Technology. The meeting began around 15:00, and lively discussions continued for two hours before we even reached the main topic of his research. Following a one-hour laboratory tour, Prof. Singh began his presentation. We had covered only the first few slides when we realized it was already around 19:00. It had been some time since we last had such an in-depth discussion, making this a particularly rewarding exchange. Afterwards, we enjoyed a delicious vegetarian meal at an Indian restaurant.

Prof. Singh’s research focuses primarily on thermal effects on clay, including moisture migration and volume change caused by temperature and temperature gradients. His work explores interactions among clay, water, and temperature in diverse applications, including geological disposal in the UK, mine waste disposal in Australia, quick clay in Norway, and thermal energy pipelines. These topics sparked considerable interest, and we look forward to continuing our discussions.

Participants (titles omitted): Wang, Watanabe, Kyokawa, and Martand Singh

Venue: Hongo Campus, The University of Tokyo
Date and time: March 19, 2026, 15:00–19:00

14th Workshp on Bentonite

A workshop was held with Nicolò Guarena of Politecnico di Torino to exchange research findings with group members.

Participants (titles omitted): Wang, Watanabe, Ruan (Waseda University), Urano (Waseda University), Cai (The University of Tokyo), Takubo (NUMO), Sato (JNFL), Yang (Tokyo Electric Power Services), Tian (Tokyo Electric Power Services), Ishii (Taiheiyo Cement), Hora (Taiheiyo Cement), Otsubo (PARI), Rawiwan (PARI), Nakamura (PARI), and Nicolò Guarena (Politecnico di Torino)

Venue: Hongo Campus, The University of Tokyo
Date and time: December 25, 2025, 13:00–16:50

Speakers and related publications:

Topic 1: Nicolò Guarena (Politecnico di Torino): Novel Perspectives on the Coupled Chemical, Electrical, and Mechanical Behaviour of Bentonite-Based Containment Barriers

Related publications:

1. Laboratory assessment of semi-permeable properties of a natural sodium bentonite

2. The role of diffusion induced electro-osmosis in the coupling between hydraulic and ionic fluxes through semipermeable clay soils

Topic 2: Yasutaka Watanabe (Central Research Institute of Electric Power Industry): Seawater impact on permeability of compacted bentonite–sand mixtures: role of montmorillonite content and its interlayer cations

Laboratory tour: Led by Wang

13th Workshp on Bentonite

Researchers from the Nuclear Waste Management Organization of Japan (NUMO) and Japan Nuclear Fuel Limited (JNFL) presented their research on bentonite used in the disposal of high-level and low-level radioactive waste.

Participants (titles omitted): Harada, Wang, Watanabe, Takayama, Ruan, Cai, Tachibana, Kyokawa, Yoshikawa, Takubo, Sato, Saito, Yagi, and several students

Venue: Hongo Campus, The University of Tokyo
Date and time: August 6, 2025, 13:00–18:10

Speakers and related publications:

Topic 1: Yusaku Takubo (NUMO): Use of Bentonite in Geological Disposal and Development of Assessment Methods for Its Long-Term Evolution under Repository Conditions

Related publication: Model development of coupled THMC processes for a geological repository at higher temperature region

Topic 2: Yasuaki Saito (JNFL) and Hisao Sato (JNFL): Basal Spacing and Number of Stacked Layers in Montmorillonite in Bentonite Used for Low-Level Radioactive Waste Disposal

Related publications:

1. Study on the Mechanism of Consistency Characteristics of Na–Montmorillonite Using Small-Angle X-Ray Scattering Method

2. Analysis of Interlayer Water in Homoionic Montmorillonite by X-Ray Diffraction and Near-Infrared Spectroscopy

11th Workshp on Bentonite

Participants (titles omitted): Sato, Yamamoto, Moriiwa, Kyokawa, Wang, Watanabe, Ito, Yoshikawa, Takayama, Ruan, Cai

Location: Online

Date: July 4, 2024, 4:00 PM - 7:00 PM

Presenters and Related Papers:

• Topic 1: Shin Sato (Obayashi Corporation) Overview of our R&D work for engineering barriers

• Topic 2: Shuichi Yamamoto (Obayashi Corporation) Pore Air Pressure Development Behavior in Bentonite-Based Engineered Barriers

10th Workshp on Bentonite

Participants: Hiroyuki Kyogawa, Hailong Wang, Yasutaka Watanabe, 

Daichi Ito, Kunlin Ruan, Guodong Cai, Tokio Morimoto,  several students

Venue: Nagoya Institute of Technology

Date: 2024.03.04  14:00～17：00

Presentation and related papers：

• Hiroyuki Kyogawa: Modeling of unsaturated bentonite

• Hailong Wang: Development of isotropic loading triaxial system

9th Workshp on Bentonite

Participants: Hiroyuki Kyogawa, Hailong Wang, Shinya Tachibana,  Yasutaka Watanabe, 

Daichi Ito, Kunlin Ruan, Guodong Cai, Tokio Morimoto,  several students

Venue:Waseda University 

Date: 2023.12.23  14:00～17：00

Presentation and related papers：

• Yasutaka Watanabe(Unpublished)

• Shinya Tachibana(Unpublished)

7th Workshp on Bentonite (Research Frontiers on Bentonite)

Date: April 17, 2023 12:55-18:35

Location: Waseda University Nishi-Waseda Campus Building 55 N Building 1F 2nd Conference Room

Sponsor: Waseda University, Central Research Institute of Electric Power Industry, Nagoya Institute of Technology, Kobe University

Co-sponsor: Waseda University Faculty of Science and Engineering Research Institute

Program

12:55-13:00 [Opening Greetings] Wang Hailong, Waseda University

13:00-13:50 [Invited lecture] (MC: Wang Hailong)

Topic 1: About the agglomeration process of colloids that interact with short-range attraction

Michio Tateno, The University of Tokyo

13:50-14:50 [Presentation Session 1] 30 minutes/Presentation (MC: Wang Hailong)

Topic 2 Utilization and issues of bentonite in radioactive waste disposal

Yasutaka Watanabe, Central Research Institute of Electric Power Industry

Topic 3: Unsaturated properties of buffer materials (swelling, compaction, strength, water retention, water permeability) and pore air pressure behavior during re-submersion

Shuichi Yamamoto, Obayashi Corporation

14:50-15:00 Coffee break

15:00-15:50 [Invited Lecture 2] (MC: Yasutaka Watanabe)

Topic 4: Development of coarse-grained molecular dynamics method for analyzing the structure of hydrous montmorillonite systems

Kazushi Kimoto, Okayama University

15:50-16:50 [Presentation Session 2] 30 minutes/Presentation (MC: Yasutaka Watanabe)

Topic 5: Continuum composition model of swelling soil focusing on mineral crystals

Hiroyuki Kyogawa, Nagoya Institute of Technology

Topic 6 Compression behavior of saturated and unsaturated bentonite and its modeling

Shin Sato, Obayashi Corporation

16:50-17:00 Coffee break

17:00-18:30 [Presentation Session 3] 30 minutes/Presentation (MC: Hiroyuki Kyogawa)

Topic 7: Rapid measurement of swelling pressure and hydraulic conductivity of bentonite-based materials Introduction to experimental technology

Daichi Ito, Waseda University

Topic 8 Separation and gelation of high-purity montmorillonite by hydrothermal reaction treatment of bentonite

Mae Yoshikawa, Central Research Institute of Electric Power Industry

Topic 9: Mysterious behavior of interlayers and interlayer water in montmorillonite

Hailong Wang, Waseda University

18:30-18:35 [Closing remarks] Hideo Komine, Waseda University

18:50-20:50 Social gathering Trattoria Matsumoto

https://tabelog.com/tokyo/A1304/A130401/13069136/dtlmenu/photo/

6th Workshp on Bentonite

Participants: Hiroyuki Kyogawa, Yasutaka Watanabe, Hailong Wang , Daichi Ito, Kunlin Ruan, several students

Date: 2023.01.20

Venue: Waseda University

Presentation and related papers：

•  Hailong Wang

Pore water density in a saturated bentonite 

5th Workshp on Bentonite

Participants: Hiroyuki Kyogawa, Yasutaka Watanabe, Hailong Wang, 

Shinya Tachibana, Daichi Ito, Kunlin Ruan, Guodong Cai

Date: 2022.10.13

Venue: Waseda University

Presentation and related papers：

• Yasutaka Watanabe

Saturated hydraulic conductivity of compacted bentonite–sand mixtures before and after gas migration in artificial seawater

4th Workshp on Bentonite

Participants: Hiroyuki Kyogawa, Yasutaka Watanabe, Hailong Wang, Daichi Ito, Kunlin Ruan, Guodong Cai, Yasuhiro Muto, Ema Yoshikawa, Shinya Tachibana, Yusuke Takayama 

Date: 2022.07.21

Venue: Niigata city

Time: 14：00～18：00

Presentation and related papers：

１．14：00～15：10　Shinya Tachibana

Constitutive model for swelling properties of unsaturated bentonite buffer materials during saturation 

2．15：10～15：55　Yasuhiro Muto (Unpublished)

3．16：05～17：15　Yusuke Takayama 

OBSERVATION OF COLLAPSE BEHAVIOR OF BENTONITE DURING SWELLING PRESSURE TEST USING X-RAY CT MEASUREMENT

4．17：15～18：00　Hailong Wang

Effects of specimen thickness on apparent swelling pressure evolution of compacted bentonite 

3st Workshp on Bentonite

Participants: Hiroyuki Kyogawa, Yasutaka Watanabe, Hailong Wang, Daichi Ito, and several students

Date: 2022.05.30

Venue: Waseda University

Presentation and related papers：

• Yasutaka Watanabe
  Saturated hydraulic conductivity of compacted bentonite–sand mixtures before and after gas migration in artificial seawater

2nd Workshp on Bentonite

Participants: Hiroyuki Kyogawa, Yasutaka Watanabe, Hailong Wang, 

Ema Yoshikawa, Daichi Ito, several students

Date: 2021.05.14

Venue: Waseda University

Presentation and related papers：

• Hiroyuki Kyogawa
  A method for extending a general constitutive model to consider the electro‐chemo‐mechanical phenomena of mineral crystals in expansive soils

• Yasutaka Watanabe
  Swelling pressure of compacted bentonite acting on constraining material with deformability

1st Workshp on Bentonite

Participants: Hiroyuki Kyogawa, Yasutaka Watanabe, Hailong Wang, 

Ema Yoshikawa, Daichi Ito, and several students.

Date: 2021.03.25

Venue: Waseda University

Presentation and related papers：

• Ito Daichi

Evaluating influence of cementation on swelling properties of bentonite buffer material based on the results of bentonite ores

• Kunlin Ruan

A Modified Kozeny-Carman Equation for Predicting Saturated Hydraulic Conductivity of Compacted Bentonite in Confined Condition

• Hailong Wang

  1. 1. A swelling pressure cell for x-ray diffraction test

     2. Effects of specimen thickness on apparent swelling pressure evolution of compacted bentonite