ASTM D4959-24

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of the standard as published by ASTM is to be considered the official document.
Designation: D4959 − 16 D4959 − 24
Standard Test Method for
Determination of Water Content of Soil By Direct Heating
This standard is issued under the fixed designation D4959; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope*
1.1 This test method covers procedures for determining the water content of soils by drying with direct heat, such as using a
hotplate, stove, blowtorch, and the like.stove or a blowtorch, where the heat is applied to the container and not directly to the soils.
1.2 This test method can be used as a substitute for Test Methods D2216 when more rapid results are desired to expedite other
phases of testing and slightly less accurate results are acceptable.
1.3 When questions of accuracy between this test method and Test Methods D2216 arise, the results of Test Methods D2216 shall
be the referee method.will be used.
1.4 This test method is applicable for most soil types. For some soils, such as those containing significant amounts of halloysite,
mica, montmorillonite, gypsum, or other hydrated materials, highly organic soils or soils that contain dissolved solids, (such as salt
in the case of marine deposits), this test method may not yield reliable water content values due to the potential for heating above
110°C or lack of means to account for the presence of precipitated solids that were previously dissolved.
1.5 Units—The values stated in SI units are to be regarded as standard. Performance of the test method utilizing another system
of units shall not be considered non-conformance. No other units of measure are included in this standard. The sieve designations
are identified using the “standard” system in accordance with Specification E11, such as 2.0-mm and 19-mm, followed by the
“alternative” system of No. 10 and ⁄4-in., respectively, in parentheses. Reporting of test results in units other than SI shall not be
regarded as nonconformance with this standard.
1.6 All observed and calculated values shallmust conform to the guidelines for significant digits and rounding established in
Practice D6026, unless otherwise superseded by this standard.
1.6.1 The procedures used to specify how data are collected/recorded or calculated, in this standard are regarded as the industry
standard. In addition, they are representative of the significant digits that generally should be retained. The procedures used do not
consider material variation, purpose for obtaining the data, special purpose studies, or any considerations for the user’s objectives;
and it is common practice to increase or reduce significant digits of reported data to be commensurate with these considerations.
It is beyond the scope of this standard to consider significant digits used in analysis methods for engineering design.
1.6.2 Significant digits are especially important if the water content will be used to calculate other relationships such as 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
This test method is under the jurisdiction of ASTM Committee D18 on Soil and Rock and is the direct responsibility of Subcommittee D18.08 on Special and Construction
Control Tests.
Current edition approved Jan. 1, 2016Feb. 1, 2024. Published January 2016February 2024. Originally approved in 1989. Last previous edition approved in 20072016 as
D4959 – 07.D4959 – 16. DOI: 10.1520/D4959-16.10.1520/D4959-24.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4959 − 24
example, if four significant digits are required in any of the above calculations, then the water content has to must be recorded to
the nearest 0.1 %, for water contents below 100 %. 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 (below 100 %); 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 %.
1.7 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 healthsafety, health, and environmental practices and determine
the applicability of regulatory limitations prior to use.
1.8 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D653 Terminology Relating to Soil, Rock, and Contained Fluids
D2216 Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass
D3740 Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in
Engineering Design and Construction
D4753 Guide for Evaluating, Selecting, and Specifying Balances and Standard Masses for Use in Soil, Rock, and Construction
Materials Testing
D6026 Practice for Using Significant Digits and Data Records in Geotechnical Data
E11 Specification for Woven Wire Test Sieve Cloth and Test Sieves
3. Terminology
3.1 Definitions—For definitions of common technical terms used in this standard, refer to Terminology D653.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 direct heating—heating, n—a process by which the soil is dried by conductive heating from the direct application of heat
in excess of 110°C to the specimen container, such as provided by a hot plate, gas stove or burner, heatlamps, or other heat sources.
Direct application of heat by flame to the specimen is not appropriate.
4. Summary of Test Method
4.1 A moist soil specimen is placed in a suitable container and its mass is determined. It is then subjected to drying by the
application of direct heat until dry by appearance, removed from the heat source, and its new mass is determined. This procedure
is repeated until the mass becomes nearly constant within specified limits.
4.2 The difference between the masses of the moist specimen and the dried specimen is used as the mass of water contained in
the specimen. The water content (expressed as a percentage) is determined by dividing the mass of water by the dry mass of soil,
multiplied by 100. For a given soil type and specimen size, the time to achieve a constant dry mass can be noted and used to
estimate drying time for subsequent tests of the same soil type using the same size specimen and drying apparatus.
5. Significance and Use
5.1 The water content of a soil is used throughout geotechnical engineering professional practice both in the laboratory and in the
field. The use of Test Methods D2216 for water content determination can be time consuming and there are occasions when a more
expedient method is desirable. Drying by direct heating is one such method. Results of this test method have been demonstrated
to be of satisfactory accuracy for use in field control work,testing, such as in the determination of water content, and in the
determination of in-place dry unit weight of soils.
5.2 The principal objection to the use of the direct heating for water content determination is the possibility of overheating the
soil, thereby yielding a water content higher than would be determined by Test Methods D2216. While not eliminating this
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volume information, refer to the standard’s Document Summary page on the ASTM website.
D4959 − 24
possibility, the incremental drying procedure in this test method will minimizereduce its effects. Some heat sources have settings
or controls that can also be used to reduce overheating. Loose fitting covers or enclosures can also be used to reduce overheating
while assisting in uniform heat distribution.
5.3 The behavior of a soil when subjected to direct heating is dependent on its mineralogical composition, and as a result, no one
procedure is applicable for all types of soils or heat sources. The general procedure of this test method applies to all soils, but test
details may need to be tailored to the soil being tested.
5.4 When this test method is to be used repeatedly on the same or similar soil from a given site, a correction factor can usually
be determined by making several comparisons between the results of this test method and Test Methods D2216. A correction factor
is valid when the difference is consistent for several comparisons, and is reconfirmed on a regular specified basis.
5.5 This test method mayis not be appropriate when precise results are required, or when minor variations in water content will
affect the results of other test methods, such as borderline situations where small variations in the measured water content could
affect acceptance or rejection.
5.6 This test method is not appropriate for specimens known to contain flammable organics or contaminants, and other test
methods should be utilized in these situations.
NOTE 1—The quality of the resultsresult produced by this test method standard is dependent on the competence of the personnel performing it and the
suitability of the equipment and facilitiesfacility used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent
and objective testing/sampling/inspection.testing/sampling/inspection/etc. Users of this test method standard are cautioned that compliance with Practice
D3740 does not in itself ensure reliable results . assure reliable results. Reliable results depend on many factors; Practice D3740 provides a means of
evaluating some of those factors.
6. Interferences
6.1 When testing sand and gravel size particles, additional care should be taken to avoid the possibility of particle shattering.
6.2 Due to the localized high temperatures in the soil during testing, the physical characteristics of the soil may be altered.
Degradation of individual particles may occur, along with vaporization, chemical transition, or loss of organics. Therefore,
specimens used in this test method shouldmust not be used for other tests subsequent to after drying.
7. Apparatus
7.1 Direct Heat Source—Any source of heat that can be directed to the soil specimen to raise the specimen temperature to or above
110°C. Commonly used sources include electric, gas, butane or oil-fired stoves, and hotplates, blowtorches, heat lamps, hair driers,
space heaters, etc. and space heaters. Heat sources that directly apply open flame to the specimen may cause extreme degradation
of the specimen along with oxidation of and depositing of soot in the specimen and shouldmust not be used.
7.2 Balances—All balances shallmust meet the requirements of Guide D4753 and this section. A Class GP2 balance of 0.1 g
readability is generally required.advised. However, the balance used may be controlled by the number of significant digits needed
(see 1.6).
7.3 Specimen Containers—Suitable containers made of material resistant to corrosion and a change in mass upon repeated heating,
cooling, and cleaning. One container is needed for each water content determination.
7.4 Container Handling Apparatus—Gloves or suitable holder for moving hot containers after drying.
7.5 Desiccator (optional)—A desiccator cabinet or jar of suitable size containing silica gel, anhydrous calcium phosphate, or
equivalent. It is preferable to use a desiccant that changes color to indicate thatwhen it needs reconstitution.to be replaced.
7.6 Miscellaneous (as needed)—Mixing tools such as spatulas, spoons, etc.;spatulas or spoons; eye protection, such as safety
glasses or goggles; dry light-weight paper ofor tissue, and knives.
D4959 − 24
8. Hazards
8.1 Container holders or gloves are recommended for handling hot containers. Some soil types can retain considerable heat, and
serious burns could result from improper handling.
8.2 Suitable eye protection such as safety glasses or goggles is recommended due to the possibility of particle shattering during
heating, mixing, or mass determinations.
8.3 Highly organic soils, and soils containing oil or other contaminants may ignite during drying with direct heat sources. Means
for smothering flames to prevent operator injury or equipment damage should be available during testing. Fumes given off from
contaminated soils or wastes may be toxic, and should be vented accordingly.
8.4 Due to the possibility of steam explosions, or thermal stress shattering of porous or brittle aggregates, a vented covering over
the sample container may be appropriate to prevent operator injury or equipment damage. This also prevents scatteringloss of the
test specimen during the drying cycle while aiding in uniform heating of the specimen.
9. Samples
9.1 Perform the water content determination as soon as practical after sampling t
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