途上国での社会基盤構造物―特に鉄筋コンクリート構造物―の老朽化に関する考察

抄録

In this paper, the authors would like to show (1) some examples of the early deteriorated Reinforced Concrete (RC) structures in developing countries with ODA, (2) poor construction technology and workmanship in site and (3) the effect of temperature on the corrosion of steel bars in reinforced concrete. Also, the authors describe the investigative approach, the construction technique and the material choice based on the situation in the developing countries.

As a result, the RC structures in the developing countries are more easily deteriorated compared to those in Japan and other developed countries. This is partly because of the fact that the temperature is relatively higher in developing countries of Southeast Asia and Africa, and therefore the percolation rate of chloride ions and water contents in concrete becomes larger, which then induces the corrosion of steel bars in concrete.

Also, in developing countries, the improvement and the specialization of construction are not advanced as in Japan and there are few professional engineers equivalent to the Japanese craftsmen. In general, the technical levels of the local supply companies are considerably lower than those in Japan. Also, the construction supplies which are prepared by those local supply companies can be low in terms of quality. Therefore, it is important that the Japanese operation staff personally check the quality and manage the supply companies appropriately at the locale. In addition, the engineers of the Japanese companies need to learn the basic knowledge about concrete technology. It is important to arrange a field supervisor who has the work experience and knowledge about the construction management and the field-oriented construction management system.