This standard specifies the procedure for the rapid determination of water content in soil using a calcium carbide gas pressure meter. It details the apparatus, reagent, testing procedure, and calculation method. This method provides a quick field alternative to the more accurate, but time-consuming, oven-drying method.
rapid moisture meter for rapid determination of water content in the soil
Quick Reference Values
Standard wet soil sample weight6 g
Typical amount of Calcium CarbideApprox. 3 g or one level spoonful
Shaking time until gauge is stableApprox. 60 seconds
Formula for dry weight moisture content (w) from gauge reading (mw)w = (mw * 100) / (100 - mw)
Key Formulas
w = [m_w / (100 - m_w)] * 100 — Conversion of moisture content from wet mass (gauge reading) to dry mass basis.
Practical Notes
The gauge reading gives moisture content by wet weight and must be converted to a dry weight basis for most geotechnical engineering calculations, a common source of error.
Calcium carbide is a hazardous material that reacts violently with water. It must be stored in an airtight container and handled with appropriate personal protective equipment.
The test's accuracy can be affected by soil containing a high percentage of organic matter or lateritic gravel, which may require specific calibration.