【Young Faculty:001】Yuya Takahashi, Assistant Professor: Concrete laboratory, Department of Civil Engineering

Education :
2008.3: Graduate from The University of Tokyo (Dept. of Civil Eng.)
2010.3: Master degree from The University of Tokyo (Dept. of Civil Eng.)
2013.3: Doctor of Engineering from The University of Tokyo (Dept. of Civil Eng.)

Work Experience :
2012.4-2013.3: Research Fellow of the Japan Society for the Promotion of Science (DC2)
2013.4-2014.1: Research Fellow of the Japan Society for the Promotion of Science (PD)
2014.2-2017.10: Research Associate, Graduate School of Engineering, Univ. of Tokyo (Civil)
2017.11- : Assistant Professor, Graduate School of Engineering, Univ. of Tokyo (Civil)

Concrete is one of the major materials which are used in infrastructures, such as roads, bridges, tunnel, dams, or the like. You can find it wherever around you and several dozens of billion m3 of concrete are produced per year all over the world. A small technical innovation at concrete engineering can have a great impact to the world industry, thus several big research projects are ongoing in US and European countries.
My main research filed is concrete engineering, especially focusing on the deterioration prediction of concrete structures. Various chemical reactions are continuously progressing in concrete and they can contribute to the long-term strength developments, while there are some harmful reactions which can make expansive reaction products and cause cracks. As examples of the harmful reactions in concrete, there can be mentioned the steel corrosion caused by chloride ion ingress in nearshore structures, and the alkali silica reaction (ASR) which creates expansive gel products through the reaction between the alkali (K and Na) in the cement paste and the reactive silica in the aggregates (Picture 1). Many structures in the world are troubled by these deteriorations and we have to predict the remaining structural performances and service lives of these deteriorated concrete structures to maintain them properly.
I am addressing this issue by utilizing simulations (Figure 1), experiments and field surveys. To achieve the reasonable predictions of the deterioration progresses, we have to consider the kinetics of chemical reactions, three dimensional volume changes of materials and the mutual interactions of crack progresses and mass transports. It is difficult to integrate all these effects, and various groups in the world are now conducting energetic researches about this issue. Our research group has been developing the integrated material-structural simulation system for concrete structures. The microscopic models are formulated in the system to describe the behaviors of molecules, crystals and amorphous phases in nanometer or micrometer scale, and are scaled up to the structural meter scale. With this multi-scale approach, we can simulate various environmental and material conditions in concrete structures, including the deterioration progress due to expansive reaction products. With updating the models to install any recent findings from the various experiments, we are now trying to achieve the life span simulations, which can contribute to the proper maintenance strategies and longer service lives of infrastructures.

A Concrete Wall damaged by Alkali Silica Reactions

Chemo-mechanical modellings of Alkali Silica Reactions in concrete

 My current interests are in boundary area between concrete engineering and other field. I have been studying the integrated material-structural problem in concrete engineering, as well as the boundary filed between concrete and geotechnical engineering. Through these research activities, I have rediscovered that the difficulty in “Engineering” can be mostly found in the boundary areas. With studying boundary research fields, I would like to develop my ability to insight the whole “Engineering”. It might lead to the breakthrough in each research field.