The Norwegian regulations to mitigate alkali aggregate reactions in concrete

Abstract

Th is paper outlines the historical developments in research on Alkali Aggregate Reactions (AAR) in Norway during the past 25 years. Norwegian regulations have proven to be valuable tools for mitigating AAR. A three step test procedure includes; the petrographical analysis, the accelerated mortar bar test and the overruling concrete prism test, the latter also used for the evaluation of binders and concrete compositions. Recent research focus has been on the utilisation of the concrete prism test as a performance test. Test results have shown that the AAR expansion is signifi cantly infl uenced by the specimen “pre-treatment”, the “test conditions” and the “prism crosssection”, primarily due to the infl uence on the rate of alkali leaching during exposure. Further research on these topics, on alkali release from aggregates and on eff ect of artifi cial alkali addition (boosting) will be carried out, both by the newly established RILEM TC “AAA” and in a Norwegian R&D project.