D 4373 =link= - Astm

ASTM D4373 is the industry standard for quickly determining the amount of carbonate in soils and soft rock. Unlike complex laboratory chemical analyses, this provides a "calcite equivalent" percentage using a portable, easy-to-use apparatus. Why do we test for it?

D4373 – 14 (or current active version: 2021) astm d 4373

) gas released when a soil specimen reacts with hydrochloric acid ( HClcap H cap C l ). The chemical reaction is: ASTM D4373 is the industry standard for quickly

| Step | Action | |------|--------| | 1 | Dry the soil sample at 105°C to a constant mass. | | 2 | Crush soil to pass a No. 200 (75 µm) sieve. | | 3 | Weigh a specimen (typically 1–10 g, depending on expected carbonate content). | | 4 | Place specimen into the reaction vessel. | | 5 | Add HCl (without allowing contact until sealed) into a separate chamber or capsule within the vessel. | | 6 | Seal the gas-measuring apparatus. | | 7 | Tip the apparatus to allow acid to contact the soil. | | 8 | Record the maximum gas pressure or volume reading after reaction stabilizes (usually 1–2 minutes). | D4373 – 14 (or current active version: 2021)

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

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.

Standard testing equipment, such as the Calcium Carbonate Content Chamber , typically includes a reaction cylinder (reactor), a pressure gauge, and an internal acid container.