Alkali-silica reaction represents a frequent reason of failure of concrete structures. Aggregates in the Czech Republic are not safe from the point of view of alkali-silica reaction; they nearly always contain deleterious phases.
The use of mineral admixtures seems to be a convenient way of eliminating the effects of alkali-silica reaction. Effects of slag, fly ash and metakaoline are demonstrated.
Dilatometric measurements are completed with the study of microstructure.