This analysis measures mortar characteristics by ASTM C-1324 “Standard Test Method for Examination and Analysis of Hardened Masonry Mortar”. ASTM C1324 petrographic analysis is often required by institutional and government project stakeholders, or for mortars with irregular ingredients. It is more extensive and time consuming than Acid Digestion, but provides the most precise data about the composition of the mortar. Modern masonry mortars need to be analyzed petrographically if accurate binder proportions are required as their unbound lime and high cement content makes acid digestion analysis inconclusive.
Analysis of historic mortars based on petrographic analysis data alone can result in inappropriate mix design as early portland cement was not nearly as strong/reactive or consistent as modern portland cement.