Moisture content by Rapid moisture meter (RMM)

Determination of moisture content by Rapid moisture meter (RMM). Rapid moisture meter gives results so quickly as compared to the oven-dry method. In this test moisture determining by chemical reaction using calcium carbide as a reagent to react with the available water in the soil producing a gas.

Test Standard : IS 2720 part 2

Test Equipments :

  1. Rapid moisture meter as per IS 12175: 1987
  2. Measuring spoon
  3. Steel balls of 12.5 mm diameter and one steel ball of 25 mm diameter
  4. Counterpoint balance
  5. Small brush
  6. Calcium carbide.


Test procedure :

  • Clean the cap and body of moisture meter with a brush.
  • take about 6 g of soil sample.
  • Set up the balance and place the sample in the pan till the mark on the balance arm mass lines up with the index mark.
    Unclamp the clamping screw to move the U-clamp off the cup. Liftoff the cup.
  • Hold the body horizontally and gently deposit one level scoopful of calcium carbide halfway inside the chamber.
  • After that lay the chamber down without disturbing the calcium carbide charge and transfer the soil weighed out as above from the pan to the cup.
  • Holding cup and chamber approximately horizontal bring them together, without disturbing sample or calcium carbide, bring the U clamp round and clamp the cup tightly into place.
  • Put the steel ball in the chamber.

Note : ( If the sample is bulky reverse the above placements, that is, put the sample in the chamber and the absorbent in the cup. In the case of clayey soils and pastes, place the 3 smaller steel balls in the cup along with the sample and larger one in the body along with the absorbent.)

  • With the gauge downwards, shake the moisture meter up and down vigorously for 5 seconds, then quickly turn it so that the gauge is upwards, give a tap to the body of the moisture meter to ensure that all the contents fall into the cup.
  • Hold the rapid moisture meter downward, again shake for 5 seconds, then turn it with gauge upwards and tap. Hold for one minute. Repeat this for the third time.
  • Once more invert the rapid moisture meter and shake up and down to cool the gas. Turn the rapid moisture meter with the gauge upwards, and dial horizontal held at chest height when the needle comes to rest.
  • Note the reading from the meter are the percentages of water on the wet mass basis.
  • Slowly release the gas pressure and Clean up the chamber.

Note :

When steel balls are used place the 3 smaller balls in the cup along with the soil and larger one in the body along with the absorbent and seal up as usual. Hold the rapid moisture meter vertical so that the material in the cup falls into the body. Now holding the unit horizontal rotate it for 10 seconds so that the balls are rolled round the Inside circumference of the body. Rest for 20 seconds. Repeat the rotation-rest cycle until the gauge reading is constant (usually this takes 4 to 8 min ). Note the reading as usual.

Calculate the moisture content

W = [M/(100-M)]*100


W = Percent water content of the dry mass

M =Water content (%) from RMM Reading

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Rajkumar ghagre

Founder & Admin of, I am a civil engineer working as a Engineer (QA/QC).

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