Determining the Moisture Content of Soil and Rock by Mass (Conventional Oven Method) - Soil Properties: Testing, Measurement, and Evaluation - page 39

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CHAPTER FOUR

CHAPTER FOUR

Determining the
Moisture Content
of Soil and Rock
by Mass (Conventional
Oven Method)

Determining the
Moisture Content
of Soil and Rock
by Mass (Conventional
Oven Method)

(Referenced Document: ASTM 2216)

The moisture content of soil (also referred to as water content ) is an in-
dicator of the amount of water present in soil. By definition, moisture
content is the ratio of the mass of water in a sample to the mass of solids
in the sample, expressed as a percentage. In equation form,

INTRODUCTION

M w
M s

w 100 (4-1)

where:
w = moisture content of soil (expressed as a percentage)
M w = mass of water in soil sample (i.e., initial mass of moist soil
minus mass of oven-dried soil)
M s = mass of soil solids in sample (i.e., the soil's “oven-dried mass”)
M w and M s may be expressed in any units of mass, but both should be
expressed in the same unit.
It might be noted that the moisture content could be mistakenly de-
fined as the ratio of mass of water to total mass of moist soil (rather than
to the mass of oven-dried soil). Because the total mass of moist soil is the
sum of the mass of water and oven-dried soil, this incorrect definition
would give a fraction in which both numerator and denominator vary
(but not in the same proportion) according to the amount of moisture

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