Assessing aggregates for alkali–aggregate reaction potential Available to Purchase

The identification of alkali-reactive aggregates has been a challenge since alkali–aggregate reactions were first diagnosed. Standards, test methods and recommendations have been developed on a local and international basis. The Rilem recommendations regarding alkali–aggregate reactions are based on a methodology in which a series of laboratory tests is suggested. The assessment starts with a petrographic examination of the aggregate, followed by rapid screening tests and concrete expansion tests. This methodology has been carried out by a number of laboratories worldwide. However, some of the tests have not been totally satisfactory as sometimes the results do not correlate with each other or with field performance. A summary of the thresholds, advantages and limitations of each test according to the findings of Rilem TC 219-ACS is presented.