Alkali–aggregate reaction: performance testing, exposure sites and regulations

Several laboratory performance tests for alkali–aggregate reaction (AAR) have been used worldwide for about 20 years. However, a review performed one of the present authors in 2006 concluded that none of the test methods meets all the criteria for an ideal performance test. In the last decade, research has been performed in several countries with the aim to improve current AAR performance test methods and develop alternative tests. The Rilem (The International Union of Laboratories and Experts in Construction Materials, Systems and Structures) Technical Committee (TC) 258-AAA (2014–2019) is also focusing on this topic. The main purpose of this technical committee is to develop and promote a reliable performance-based testing concept for the prevention of deleterious AAR. Strong emphasis will be placed on the implementation of the Rilem methods and recommendations as national and international standards. It is crucial to link the results from the accelerated laboratory testing to field behaviour, primarily against field exposure sites. Some results from such exposure sites are included in this paper.