The availability of high quality aggregates for concrete is often conditioned by increasingly restrictive environmental restraints. The limited availability of natural aggregates free of reactive minerals imposes the use of lower quality or not adequately tested aggregates, thus increasing the risk of alkali-aggregate reactions. This paper reports on the use of three accelerated test methods - infrared IR spectroscopy, mortar bar expansion tests in a 1 N NaOH bath at 80 degrees C, or in a saturated NaCl bath at 50 degrees C - to evaluate the potential reactivity of opal, fused silica, Nymolle and Torre Lago sands. Macro-crystalline quartz was used as a reference aggregate, and classical ASTM test methods were adopted as reference tests. It was found that the NaOH bath test method is the most suitable for evaluating the alkali reactivity of the aggregates tested, and that the mineralogical composition of the cement significantly affects the expansion level of mortar bars in both the NaOH and NaCl bath tests.