What is the Target of Your Research?

Concrete, which is created by the chemical reaction between water and cement, is a typical construction material that has supported our society since the Roman Era. These days our cities are ironically illustrated as concrete jungles, but concrete continues to be used despite this image.

Why is this so? Because concrete is really cheap (approximately \15/liter) and can be made everywhere (except for the polar regions), and we have never found any alternative.

I’m engaged in the social activities and research to make structures (infrastructures), such as bridges, dams and tunnels, which are mainly built of concrete, more strong, beautiful and durable.

 

What Kind of Social Activities are You Engaged in?

Fig. 1 Design Standards

Since I work in the engineering field, my research should be useful for practical life. More specifically, my role is to make cutting-edge technology (research results) in design and maintenance of concrete structures more available, so that the forefront of society can use it.
For example, in order to construct a bridge girder, we have to check or verify quantitatively whether it will fail due to earthquakes or whether it will swing too much when traffic passes over it. That is, the so-called design must be done. I’m drafting design standards for concrete structures (Fig. 1) in collaboration with researchers and engineers all over Japan. As the environment around society changes, the design methods must be revised to keep up with these changes. Since the structures we deal with have a highly public nature, the design standards are open to public. They are available at bookstores so you can even take a look at them.

 

What Kind of Research are You Conducting?

Fig. 2 Physicochemical Properties Based on Analysis Fig. 3 Numerical Analysis Simulating a Break

One of my research subjects is developing a safety performance evaluation method for concrete structures. I am creating a method to predict at which level the safety of a structure is for a given time period, for example, its current safety status, ten years later or 100 years later. Needless to say, concrete structures are affected by many factors because they stand outside. Those factors include earthquakes or automobiles, changes in temperature or humidity and the salt content blown from the ocean or the salt content used in antifreeze that is applied to prevent traffic accidents. I am evaluating the performance of structures in their actual environments, first by understanding the physicochemical and mechanical properties of the concrete affected simultaneously by multiple factors at a scale of several millimeters or more (Fig. 2), and then scaling up these results to several tens of centimeters and several meters for the structures, while also integrating a numerical analysis approach (Fig. 3) and experimental approach (Fig. 4).

(a) Analysis at a Millimeter Scale (b) Analysis at a Centimeter Scale (c) Analysis at a Meter Scale Fig. 4  Experiments using Multiple Scales

 

What Will be Your Next Goal?

I would like to establish a new design method. The concrete structures are composed of multiple “members” in a framework, such as beams, columns and plates. I would like to develop a design concept where the designer or civil engineers has free range to come up with his or her own idea or plan but incorporates various types of members to make the structure last longer by optimizing its performance and making it effective for a long period of time, such as 300 years. And at the same time, I would like to develop a method to convert this concept into tangible forms. In this concept, the members of the framework would be divided into the following: “replacement components” which might be replaced at some point, “permanent components” which are manufactured using highly durable materials and will be used permanently without being replaced, and “recycled components” which would be recovered from other dismantled structures and then reused. Structures should exist for the society and people. In our mature society, the time of the manufacturing cheap things in large quantities has come to an end. A new design method must be based on a life cycle value that not only reflects cost but also sustainability and risk.