Microstructure parameters affecting alkali–silica reactivity of aggregates

Quartz-rich aggregates were investigated, with the purpose of detecting the parameters facilitating the alkali–silica reactivity (ASR) of aggregates. ASR was attributed to their microstructure. Both decreasing grain size and elongated grain shape increase the specific surface, and increase the ASR. The degree of deformation and recrystallization is suggested to be responsible for ASR, due to its effects on grain size and grain shape. A high degree of ASR was found to be connected with those samples which had recrystallized by a low-temperature recrystallization regime, characterised by very small grains.