Alkali carbonate reaction expansion of dolomitic limestone aggregates with porphyrotopic texture

Effects of porphyrotopic textures on expansion of dolomitic limestone aggregates due to alkali-carbonate reaction (ACR) are presented. The dispersed distribution of dolomites in the texture of aggregates can be divided into pophyrotopic-M, psedoporphyrotopic-M and porphyrotopic-S types. It is proved that porphyrotopic textures are more important to ACR expansion than lithologic species of dolomitic limestones. The dolomitic limestones with both porphyrotopic-M or psedoporphyrotopic-M texture and the small size of dolomite crystals are expected to be highly alkali-carbonate reactive. These aggregates can be found not only in dolomitic micritic limestones but also in dolomitic micritic allochemical limestones as well as dolomitic sparry allochemical limestones. (C) 2002 Elsevier Science B.V. All rights reserved.