Evaluation of expansion capacity of concrete cores from ASR-affected structures under different storage conditions.

In this study, concrete specimens containing alkali-silica reactive aggregates with and without steel plate strengthening were exposed to the outdoor environment for seven years in order to investigate their long-term expansion behaviour due to alkali-silica reaction by periodical measurement. Cores drilled from these specimens were then subjected to two types of accelerated tests in accordance with JCI-DD2 and ASTM C 1260 methods, to determine their expansion capacities. During the immersion in a sodium hydroxide solution in accordance with ASTM C 1260, the concentration and temperature of the solution were changed in various ways to compare the resultant expansion properties of cores, thereby exploring the optimum storage conditions for this method. This elucidated the relationship between the expansion and the sodium hydroxide concentration and the storage temperature in the ASTM C 1260 method and revealed that the expansion capacity of cores immersed in a sodium hydroxide solution with a concentration of 0.5 N and a temperature of 40 degrees centigrade corresponded well with the behaviour of actual structures. These storage conditions were therefore found more effective than the currently specified conditions as a new method of evaluating the expansion capacity of cores taken from structures deteriorated by alkali silica reaction. (a) For the covering entry of this conference, please see ITRD abstract no. 0612AR242E.