Structural properties of quartz and their potential role for ASR

Quartz is the predominant silica polymorph in alkali-reactive aggregate materials. Being a major constituent of the Earthʹs crust as well, quartz is stable under a broad range of conditions including pressure, temperature, fluids present, postdeformation, etc. The conditions under which a particular quartz was formed are reflected in its qualities, including the crystal structural details and its (trace) element composition. However, current testing methods to determine the alkali–silica reaction expansion potential of aggregate materials do not address these qualities directly. To gain an idea which qualities affect the dissolution behavior of quartz under ASR conditions, it might be useful to first consider the geological conditions, and apply these to concrete.