ASTM D3042

Insoluble Residue in Carbonate Aggregates

Applicability: Applies to carbonate aggregates — primarily limestone and dolomite — used in construction applications including concrete, asphalt, and base course. The method is limited to carbonate-bearing materials and is not appropriate for siliceous or non-carbonate aggregates, which would yield misleading results due to their low solubility in acid.

Purpose: Determines the percentage of acid-insoluble residue (clay, silt, quartz, and other non-carbonate impurities) by dissolving the carbonate fraction in dilute hydrochloric acid and gravimetrically measuring the remaining insoluble material. Insoluble residue content is an indicator of aggregate purity, and results are used in acceptance testing and quality control to predict performance in concrete and pavement applications, where excessive impurities can reduce bond strength and durability.