Alkali-carbonate reaction (ACR)
Water
Reaction of alkalis which occurs between certain argillaceous dolomitic limestones and the alkaline pore solution in the concrete and causes expansion and extensive cracking. Expansive dolomite limestones are characterized by a matrix of fine calcite and clay minerals with scattered dolomite rhobohedra. This reaction usually occurs early and structures may show cracking within 5 years after construction. See alkali-aggregate reaction.