Development and Practicability Study on Methods for Assessing Environmental Impact of Concrete

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The aim of this study is to develop an evaluation method of environmental impact of concrete in which an action toward effective uses of resources and sustainable development becomes practicable in terms of economical aspects. The development of an evaluation system of materials for concrete and the proposal of methods for evaluating environmental impact of concrete were discussed in this study.In the development of an evaluation system of materials, the effects of heavy metal leaching from concrete on environmental impact was investigated. As a result, it was found that current batch tests of heavy metal leaching in which samples were granulated were not suitable for the prediction of long-term behavior of heavy metal leaching from concrete structures. Analytical evaluation of long-term heavy metal leaching from concrete structures will be much better using the apparent diffusion coefficient of heavy metal in concrete which can be estimated from the results of the tank leaching tests.After the preparation of inventory data, two kinds of methods for evaluating environmental impact of concrete structures were proposed. For inventory data, 91 items associated with material manufacture, construction, demolishment, disposal and reuse of concrete structures have been prepared regarding the consumptions of energy, mineral resources (non-metallic and ferric) and energy resources (coal, oil and natural gas), the emissions of CO_2, NO_x, SO_x and dusts and the use and emission of wastes. In terms of the performance-based design concept, an evaluation method verifying environmental performance and an evaluation method considering environmental performance were proposed. In both methods, the degree of environmental impact in the life cycle of concrete structures was defined as environmental performance. Since these methods include the integration of environmental impact factors and consider the effect of construction cost, they should be sufficiently practical.