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, psedopor-phyrotopic-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.