2013 Volume 69 Issue 4 Pages 361-376
This paper shows the results of 23-year outdoor exposure test of concrete specimens made with 94 aggregate collected from various area of Japan. ASR risk of rock types in Japan is discussed with the data of cracking of exposed test specimens, test results of alkali-silica reactivity of aggregate by chemical method (JIS A 1145) and mortar-bar method (JIS A 1146).
Results of exposure test of concrete specimens whose Na2O equivalent alkali content was 5.0kg per cubic meter, basically reconfirms the existing knowledge of alkali-silica reactivity of Japanese aggregate. For instance, post-Miocene volcanic rocks in Japan are frequently reactive. On the other hand, cracking due to ASR was occurred in some concrete specimens made with pre-Miocene volcanic rocks and hypabyssal rocks though these types of rocks in Japan has been thought to be non-reactive. In these cases, it is estimated that late-expansive ASR has occurred and test results of alkali-silica reactivity of aggregate by chemical method and mortar-bar method was not suitable.
Cracking of concrete specimens are also observed in low-alkali concrete whose Na2O equivalent alkali content was 3.0kg per cubic meter.
