EXPOSURE test results for underground structures damaged by ASR

Recently, underground structures, for example footings and columns, which have degenerated due to Alkali Silica Reaction (ASR) have been discovered in Japan. In order to perform appropriate diagnosis of these structures, it is necessary to acquire a large amount of knowledge regarding underground structure degeneration caused by ASR, such as the conditions under which ASR occurs in underground structures, and the internal degradation conditions. For this reason, road administrators are unable to perform sufficient maintenance, and this constitutes a serious problem with respect to safe operation of the road network. Hence, in order to obtain the relevant knowledge, a long term exposure test has been performed under actual conditions, up to the present time, and the cracks and strain in the footings and temperature and water level in the exposure environment have been measured. In addition, we have analyzed the differences in the degradation of footings caused by the environment with respect to the water, air and underground conditions, and used the measured data to examine the reasons for these differences.