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|These test methods cover the laboratory determination of the
water (moisture) content by mass of soil, rock, and similar
materials where the reduction in mass by drying is due to loss of
water except as noted in 1.4, 1.5, and 1.7. For simplicity, the
word "material" shall refer to soil, rock or aggregate whichever is
Some disciplines, such as soil science, need to determine water
content on the basis of volume. Such determinations are beyond the
scope of this test method.
The water content of a material is defined in 3.2.1.
The term "solid material" as used in geotechnical engineering is
typically assumed to mean naturally occurring mineral particles of
soil and rock that are not readily soluble in water. Therefore, the
water content of materials containing extraneous matter (such as
cement etc.) may require special treatment or a qualified
definition of water content. In addition, some organic materials
may be decomposed by oven drying at the standard drying temperature
for this method (110°C). Materials containing gypsum (calcium
sulfate dihydrate) or other compounds having significant amounts of
hydrated water may present a special problem as this material
slowly dehydrates at the standard drying temperature (110°C) and at
very low relative humidity, forming a compound (such as calcium
sulfate hemihydrate) that is not normally present in natural
materials except in some desert soils. In order to reduce the
degree of dehydration of gypsum in those materials containing
gypsum or to reduce decomposition in highly/fibrous organic soils,
it may be desirable to dry the materials at 60°C or in a desiccator
at room temperature. Thus, when a drying temperature is used which
is different from the standard drying temperature as defined by
this test method, the resulting water content may be different from
the standard water content determined at the standard drying
temperature of 110°C.
NOTE 1—Test Method D2974 provides an alternate procedure for
determining water content of peat materials.
Materials containing water with substantial amounts of soluble
solids (such as salt in the case of marine sediments) when tested
by this method will give a mass of solids that includes the
previously soluble dissolved solids. These materials require
special treatment to remove or account for the presence of
precipitated solids in the dry mass of the specimen, or a qualified
definition of water content must be used. For example, see Test
Method D4542 regarding information on marine sediments.
This test standard requires several hours for proper drying of
the water content specimen. Test Methods D4643, D4944 and D4959
provide less time-consuming processes for determining water
content. See Gilbert2 for details on the background of
Test Method D4643.
Two test methods are provided in this standard. The methods
differ in the significant digits reported and the size of the
specimen (mass) required. The method to be used may be specified by
the requesting authority; otherwise MethodAshall be performed.
Method A—The water content by mass is recorded to the
nearest 1 %. For cases of dispute, Method A is the referee
Method B—The water content by mass is recorded to the
nearest 0.1 %.
This standard requires the drying of material in an oven. If the
material being dried is contaminated with certain chemicals, health
and safety hazards can exist. Therefore, this standard should not
be used in determining the water content of contaminated soils
unless adequate health and safety precautions are taken.
Units—The values stated in SI units shall be regarded
as standard excluding the Alternative Sieve Sizes listed in Table
1. No other units of measurement are included in this test
Refer to Practice D6026 for guidance concerning the use of
significant figures that shall determine whether Method, A or B is
required. This is especially important if the water ntent will be
used to calculate other moist mass to dry mass or vice versa, wet
unit weight to dry unit weight or vice versa, and total density to
dry density or vice versa. For example, if four significant digits
are required in any of the above calculations, then the water
content must be recorded to the nearest 0.1 %. This occurs since 1
plus the water content (not in percent) will have four significant
digits regardless of what the value of the water content is; that
is, 1 plus 0.1/100 = 1.001, a value with four significant digits.
While, if three significant digits are acceptable, then the water
content can be recorded to the nearest 1 %.
This standard does not purport to address all of the safety
concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and
health practices and determine the applicability of regulatory
limitations prior to use.
*A Summary of Changes section appears at the end of this
2 Gilbert, P.A., "Computer Controlled Microwave Oven
System for Rapid Water Content Determination," Tech. Report
GL-88–21, Department of the Army, Waterways Experiment Station,
Corps of Engineers, Vicksburg, MS, November 1988
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