●Introducing Studies of This Lab.
Studies on shear failure are traditional and important research topics evaluating structural performance of reinforced concrete structures. In our research group, complicated structural behaviors affected by materials properties have been studied by experimental and numerical methods. Effects of volumetric changes, fracture properties, creep in concrete materials on the shear failure are key factors in our research topics.
[Related publications]
Nakarai, K., et al., Shear Strength of Reinforced Concrete Beams: Concrete Volumetric Change Effects. Journal of Advanced Concrete Technology, 2016. 14: p. 229-255.
Nakarai, K., et al., Shear Strength of Reinforced Limestone Aggregate Concrete Beams. ACI Structural Journal, 2017. 114(04).
Saifullah, H.A., et al., Shear Creep Failures of Reinforced Concrete Slender Beams without Shear Reinforcement. ACI Structural Journal, 2017. 114(6): p. 1581-1590.
Xiangen Wang., et al., Effect of water-cement ratio, aggregate type, and curing temperature on the fracture energy of concrete, Construction and Building Materials, 2020. 259(30): 119646.
Importance of studies on durability of concrete structures is significantly increasing. In our research group, several topics on the durability issues have been investigated. For example, to construct durable concrete structures, applicability of new non-destructive testing methods has been investigated through laboratory and site measurements. Furthermore, to predict remaining service life of existing concrete structures under severe environmental conditions, diagnosis of deterioration in structures has been discussed with site measurement and numerical analysis.
[Related publications]
Nakarai, K., et al., Long-term permeability measurements on site-cast concrete box culverts. Construction and Building Materials, 2019. 198: p. 777-785.
Nguyen, M.H., et al., Validation of simple nondestructive method for evaluation of cover concrete quality. Construction and Building Materials, 2019. 201: p. 430-438.
May Huu Nguyen., et al., Service life prediction of steam-cured concrete utilizing in-situ air permeability measurements, Cement and Concrete Composites, 2020. 114.
Expansive concrete can improve performance of concrete by compensating shrinkage and/or applying chemical prestressing. In our research group, applicability of a new simplified evaluation method has been investigated with proposed equations. Performance evaluation of steam-cured expansive concrete is also target of this research project.
[Related publications]
Nguyen, H.V., et al., Applicability of a simplified estimation method to steam-cured expansive concrete. Cement and Concrete Composites, 2019. 95: p. 217-227.
Hoang Viet Nguyen., et al., Effects of slag type and curing method on the performance of expansive concrete, Construction and Building Materials, 2020. 262(30), 120422.
Cement-treated soils can be applied for improving properties of soils foundations and constructing high-performance soil structures. In our research group, physicochemical properties of the cement-treated soils have been investigated using the latest knowledge in the fields of cement chemistry and concrete engineering.
[Related publications]
Nakarai, K. and T. Yoshida, Effect of carbonation on strength development of cement-treated Toyoura silica sand. Soils and Foundations, 2015. 55(4): p. 857-865.
Ho, L.S., et al., Analysis of strength development in cement-treated soils under different curing conditions through microstructural and chemical investigations. Construction and Building Materials, 2018. 166: p. 634-646.
Ho, L.S., et al., Effect of internal water content on carbonation progress in cement-treated sand and effect of carbonation on compressive strength. Cement and Concrete Composites, 2018. 85: p. 9-21.
Kenichiro Nakarai., et al., Physicomechanical properties and durability of a new lightweight porous mortar utilizing woodchips, Journal of Cleaner Production, 2019. 235: p.158-165.
In underground engineered systems consisting of cementitious and clay materials, strong chemical gradients drive calcium leaching from cement to clay. In our research group, to contribute to the fundamental understanding of interface evolution, alteration mechanisms of calcium leaching and pore clogging at the interface have been investigated with accelerated experiments and numerical simulation.
[Related publications]
Nakarai, K., T. Ishida, and K. Maekawa, Modeling of Calcium Leaching from Cement Hydrates Coupled with Micro-Pore Formation. Journal of Advanced Concrete Technology, 2006. 4(3): p. 395-407.
Nakarai, K., T. Ishida, and K. Maekawa, Multi-scale physicochemical modeling of soil-cementitious material interaction. Soils and Foundations, 2006. 46(5): p. 653-663.
We are looking for excellent graduate course students (master and doctor) and postdocs. To join us, for example, Japanese government provides the following scholarship/fund for you.
MEXT scholarship program for international students:
https://www.studyjapan.go.jp/en/toj/toj0302e.html
JSPS Research Fellowships for Young Scientists: https://www.jsps.go.jp/english/e-pd/index.html
Candidates must have certificates of their English skills for conducting research projects and for publishing papers in international journals (SCI journals with high impact factors).
Dr. Naomi Sasaki obtained her doctoral degree in 2015. The title of her dissertation was "Development of Resin Injection Repair Method of Honeycombing in Concrete Structures."
Dr. Yuki Chikahiro obtained his doctoral degree in 2016. The title of his dissertation was "Analysis and Optimization Approach of Scissors-Type Bridge based on Equilibrium Equations."
Dr. Ho Si Lanh obtained his doctoral degree in 2018. The title of his dissertation was "Analysis of Strength Development Mechanism of Cement-Treated Soils under Different Curing Conditions through Chemical and Microstructural Investigations."
Dr. Halwan Alfsa Saifullah obtained his doctoral degree in 2018. The title of his dissertation was "Shear Creep Failures of Reinforced Concrete Beams without Shear Reinforcement."
Dr. Nguyen Viet Hoang is conducting his research on performance evaluation of expansive concrete.
Mr. Hidefumi Izuo is conducting his research on long-term performance evaluation of cement-treated soils.
Dr. Nguyen Huu May is conducting his research on cover concrete quality inspection.
Mr. Bui Cong Do is conducting his research on shear strength prediction of reinforced concrete structures.
Mr. Masayuki Yamamoto is conducting his research on durability assessment of concrete structures damaged by chloride attack.
