Comparative assessment of analytical methods for calcium carbonate determination in sands

Accurate quantification of calcium carbonate (CaCO3) in soil is critical for geoenvironmental engineering, influencing soil stabilization, carbon sequestration, and climate-resilient design. This study compares four commonly used analytical methods—Loss on Ignition (LoI), Total Inorganic Carbon (TIC), X-Ray Diffraction (XRD), and a Calcium Carbonate Analyzer (CCA)—over CaCO3 concentrations from 0.3% to 50%. Controlled sand samples with known carbonate contents were tested to assess each method’s accuracy, precision, and reproducibility. Although LoI proves the most practical due to its simplicity and throughput, all methods face marked difficulties at low concentrations. Root Mean Square Error (RMSE) analysis shows that small discrepancies at low CaCO3 levels can produce disproportionately large relative errors, obscuring actual measurement uncertainties. Factors such as sample representativeness, operator handling, and instrument resolution further amplify inconsistencies, emphasizing the need for more rigorous protocols. Crucially, none of the evaluated methods consistently captures very low CaCO3 concentrations, posing significant challenges for soil carbon capture initiatives, regulatory compliance, and soil management practices. These findings highlight the urgent need to refine existing procedures or use alternative approaches to more accurately quantify CaCO3 content at low levels, thereby enhancing confidence in research outcomes and applied engineering solutions.