ASR problems in Japan and a case of ASR found in Thailand

Alkali silica reaction, ASR is still a durability problem in Japan although countermeasures have been established since 1986. The problems of this Japanese situation are thought to be caused by lack of verification of the effectiveness of the adopted countermeasures. In this critical review, the background of the Japanese countermeasures against ASR and a new approach that Japan has to introduce are explained. It will be informative for many countries to prepare ASR countermeasures. As an example of new methodology, a case of ASR damage in Thailand was analyzed from the viewpoint of petrography using concrete thin section. The ASR found in a footing was caused by microcrystalline quartz in granite mylonite, which is typical mineral for late expansion. Although ettringite formation was accompanied, the major mechanism of expansion is considered as ASR judging from the texture of expansive phase produced in aggregate and cement paste. Another important highly reactive phase was identified during this analysis. Mica in granite can be altered and generate highly reactive opal in hot and humid climate, which is a typical mineral for rapid expansion. This alteration product can be common all over Southeast Asia and considered as a possible serious cause of ASR damages.

Author: S. Hirono, K. Yamada, Y. Ando, K. Torii

Section: Concrete

Keywords: alkali silica reaction, microcrystalline quartz, granite mylonite, opal