LONG-TERM FIELD INSPECTION USING A DAM-BODY AND SPECIMENS UNDER FROST CLIMATE

摘要

The authors have conducted long-term field tests of the dynamic modulus of elasticity of dam concrete over a 36-year period at three different locations in Japan where there is a high risk of freezing and thawing. This study involves a dam-body, block specimens, and small specimens. In terms of influences on measurement results, the effects of specimen dimensions and part in specimen were greater than the effects of environmental and mix proportion conditions. It is notable that effects of entrained-air on concrete durability were not clear under field exposure test. However, there are still a number of issues that need to be examined in further depth, including the relationship between the densification of concrete structures due to pozzolan and resistance to freezing and thawing, as well as the effects on measurement results of the surface condition near the measurement point. These are issues for future study. The conditions of laboratory freezing and thawing tests are severer than those of field exposure tests with mass concrete structure in Japan's cold regions. Measurements and visual observations indicate that the dams which have been studied remain sound.