Automated Mineralogical Analysis (QEMSCAN®) as a Complementary Petrographic Tool in Assessing the Potential Alkalis Release from Aggregates

Though an important subject that has been investigated for several decades, the full understanding of the alkali release from aggregates, its contributing factors and role in the alkali-silica reaction still remains a challenge for the scientific community. Recently, the RILEM AAR-8 test method was developed and several improvements to this methodology have already been proposed. In this paper, automated scanning mineralogy (QEMSCAN®) is introduced as a complementary tool for petrographic characterization in order to better understand the factors contributing to the alkali release from aggregates with a similar mineralogy. It was used to examine distinctive textures, grain sizes and alteration of a mylonite, a cataclasite, a gneiss, a granite and an altered granite. The QEMSCAN® analysis enabled a more thorough understanding of the aggregates whilst complimenting the optical petrography.