Japan Society of Civil Engineers 2010 Annual Meeting
Panel Discussion
Creation of Environmentally Conscious Concrete Material Science

Coodinator:
Hidenori Hamada (Kyoto University)
Panelist:
Kenji Kawai (Hiroshima University)
Katsunori(??)Ayano(Okayama University)
Makoto Hisada(Tohoku University)
Kimitaka Uji(Tokyo Metropolitan University)
Takuya Hasegawa(Hokkaido University)
Takeshi Yamagata(Japan Cement Association)
Hiroshi Watanabe(Public Works Research Institute) Shinichi Miyazato(Kanazawa Institute of Technology)
Yasutaka Sagawa(Kyushyu University)

This panel discussion was held by the Concrete Committee during the Japan Society of Civil Engineers 2010 National Meeting at Hokkaido University on September 1, 2010. It was chaired by Hidenori Hamada, a professor of Kyushyu University, on the theme of the creation of environmentally conscious concrete material science. Panelists gave presentations and had meaningful exchange of views with many participants during the discussion session.

The main purpose of the panel discussion was as follows: As public concerns have recently been growing over global environmental issues, the construction and concrete industries are urged to take environmental preservation measures. Essential countermeasures against the issues are to make steady progress on the "advancement of environmentally conscious material technology" and "establishment of material supply systems." The Committee established a "Subcommittee on Creation of Environmentally Conscious Concrete Material Science" where discussions have been repeated on how the materials and their supply systems should be to expand the conventional system of concrete engineering and also how to train engineers. Through the panel discussion, it was clarified what must be done to make the construction industry sustainable.

At the panel discussion, discussions were conducted on the environmentally conscious concrete material science on the following theme. The discussions are outlined below.

1) Environmentally conscious concrete is defined as the concrete constructed of materials with minimum loads on the environment. According to this definition, the environmentally conscious concrete is close to the environmental load-reducing concrete that utilizes wastes and byproducts. The definition also has the meaning that two or more factors, such as transportation and CO2 emissions, are comprehensively evaluated.

2) To evaluate the "minimum loads on the environment" in the definition, quantitative evaluation indexes are necessary. The quantitative evaluation indexes of the environmentally conscious concrete are environmental load index, IL, CO2 emission index, IG, and recycling ratio index, IW. The index I is defined as I = IL + IG + IW. Each index is given by the following equation.

IL = 1 - (production and shipping distance, km, - 50)/1,000

IG = (reduction in CO2 emissions with use, %)/25

IW = (quantity of recycled resources)/(quantity of virgin resources + quantity of recycled resources + quantity of wastes generated)

The data obtained based on these indexes were presented.

At the panel discussion, it was pointed out that the extension of the life of structures was not reflected in the indexes, and a question was raised whether these three indexes were really independent of each another. The responses to these questions were that a temporal axis was to be taken into account, and that the indexes were provisional and further consideration was to be given based on the results of evaluation.

3) As the system of material science with the environmentally conscious concrete incorporated, the current state and problems of the cement and recycled aggregate industries were clarified. The cement industry utilizes wastes and byproducts, which account for 45% of the total, in manufacturing cement with the world's top-class energy efficiency, which contributes toward sustainable society. The further prospective of the industry is that international contribution through technology transfer will be promoted. The recycled aggregate industry has higher environment-conscious performance than the ordinary aggregate industry but is inferior in quality and CO2 emissions to the ordinary aggregate industry. So it is difficult to balance the cost, quality, and environmental load, and an integrated system of quality, policy, production, and distribution is necessary.

4) As a system of manufacturing the environmentally conscious concrete, the term “green procurement” was explained. It was pointed out that environmental loads should be taken into consideration in the purchase and procurement of concrete. The problems to be solved are the rational evaluation method based on two or more evaluation axes and the establishment of requirements for the assurance of performance. The topics for discussion at the panel discussion were the efforts of the Architectural Institute of Japan as a reference system and other various systems. It was clarified that legislative response would be required for the use of byproducts and that efforts should be expended toward various systems to reduce environmental loads and lengthen the service life of buildings but further study would be necessary.

5)To train engineers and technicians to take into account environment consciousness, the Concrete Educational Research Subcommittee held seminars and training sessions for young and mid-career researchers. The Subcommittee performs activities with the objective of training the researchers so that everyone can conduct research actively, judge information precisely, and communicate with everyone else.

The results of the panel discussion were the clarification of the meaning of environmental consciousness and the clear definition of the environmentally conscious concrete that was not defined in the conventional concrete engineering. The results presented a guideline for the construction of the concrete engineering that would respond to the future society.