Astm D 4373 -

[ CaCO_3 + 2HCl \rightarrow CaCl_2 + H_2O + CO_2 \uparrow ]

This test method covers the quantitative determination of the carbonate content (primarily calcium carbonate, CaCO₃) in soils, using a gasometric method. It is suitable for both fine-grained and coarse-grained soils, as well as soft rock and aggregate materials.

A calibrated manometric or volumetric device (typically a or similar gas-measuring apparatus) measures the pressure or volume of CO₂ evolved. This measurement is directly proportional to the CaCO₃ content, which is expressed as a percentage of the dry soil mass. astm d 4373

1. Title Standard Test Method for Rapid Determination of Carbonate Content of Soils

| Sample ID | Dry Mass (g) | CO₂ Reading (mL) | CaCO₃ Equivalent (%) | |-----------|--------------|------------------|------------------------| | S-01 (CL) | 5.00 | 38.5 | 10.2 | | S-02 (GW) | 10.00 | 122.0 | 32.8 | [ CaCO_3 + 2HCl \rightarrow CaCl_2 + H_2O

The method relies on the chemical reaction between carbonates present in the soil and hydrochloric acid (HCl). The reaction produces carbon dioxide (CO₂) gas.

D4373 – 14 (or current active version: 2021) This measurement is directly proportional to the CaCO₃

[ \textCarbonate (%) = \frac\textCO_2 \text pressure/volume reading\textDry soil mass \times \textCalibration factor ]