Volume 3, Issue 9 (October 2006)
Effect of Aggregate Particle Size on Determining Alkali-Silica Reactivity by Accelerated Tests
For assessing the rock applicability of accelerated tests for alkali-aggregate reactivity and the effect of aggregate particle size on determining alkali reactivity of concrete aggregates in accelerated tests, experimental studies on microstructure and expansion behaviors of Potsdam sandstone and a Norwegian quartzite were conducted in Concrete Prism Test and in various accelerated tests, i.e., Accelerated Mortar Bar Test, Chinese Autoclave Method, and Chinese Accelerated Mortar Bar Test. Results indicate that, in comparison with Concrete Prism Test results, the alkali expansivity of both rocks are generally underestimated in these accelerated tests. It is mainly attributed to the use of a large proportion of very fine aggregate particles in which the original microtexture characteristic of rocks was lost during sample preparation. The effects of microtexture and the particle size of aggregate on reasonable prediction of alkali expansivity of aggregates in concrete by accelerated tests were discussed.