ASTM D4643-08
(Test Method)Standard Test Method for Determination of Water (Moisture) Content of Soil by Microwave Oven Heating
Standard Test Method for Determination of Water (Moisture) Content of Soil by Microwave Oven Heating
SIGNIFICANCE AND USE
The water content of a soil is used throughout geotechnical engineering practice both in the laboratory and in the field. The use of Test Method D 2216 for water content determination can be time consuming and there are occasions when a more expedient method is desirable. The use of a microwave oven is one such method.
The principal objection to the use of the microwave oven for water-content determination has been the possibility of overheating the soil, thereby yielding a water content higher than would be determined by Test Method D 2216. While not eliminating this possibility, the incremental drying procedure described in this test method will minimize its effects. Some microwave ovens have settings at less than full power, which can also be used to reduce overheating.
The behavior of a soil, when subjected to microwave energy, is dependent on its mineralogical compositions, and as a result no one procedure is applicable for all types of soil. Therefore, the procedure recommended in this test method is meant to serve as a guide when using the microwave oven.
This test method is best suited for minus No. 4 sized material. Larger size particles can be tested; however, care must be taken because of the increased chance of particle shattering.
The use of this method may not be appropriate when highly accurate results are required, or the test using the data is extremely sensitive to moisture variations.
Due to the localized high temperatures that the specimen is exposed to in microwave heating, the physical characteristics of the soil may be altered. Degregation of individual particles may occur, along with vaporization or chemical transition. It is therefore recommended that samples used in this test method not be used for other tests subsequent to drying.
Note 1—The quality of the results produced by this test method is dependent on the competence of the personnel performing it and the suitability of the equipment and facilities used. Agencies that me...
SCOPE
1.1 This test method outlines procedures for determining the water (moisture) content of soils by incrementally drying soil in a microwave oven.
1.2 This test method can be used as a substitute for Test Method D 2216 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 Method D 2216 arise, Test Method D 2216 shall be the referee method.
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 in which the pore water contains dissolved solids (such as salt in the case of marine deposits), this test method may not yield reliable water content values.
1.5 The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this test method.
1.6 Refer to Practice D 6026 for guidance concerning the use of significant figures. This is 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 example, if four significant digits are required in any of the above calculations, then the water content has to 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 %.
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 t...
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Designation: D4643 − 08
Standard Test Method for
Determination of Water (Moisture) Content of Soil by
1
Microwave Oven Heating
This standard is issued under the fixed designation D4643; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope* 1.7 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.1 Thistestmethodoutlinesproceduresfordeterminingthe
responsibility of the user of this standard to establish appro-
water (moisture) content of soils by incrementally drying soil
priate safety and health practices and determine the applica-
in a microwave oven.
bility of regulatory limitations prior to use. See Section 7.
1.2 This test method can be used as a substitute for Test
Method D2216 when more rapid results are desired to expedite
2. Referenced Documents
other phases of testing and slightly less accurate results are
2
2.1 ASTM Standards:
acceptable.
D653 Terminology Relating to Soil, Rock, and Contained
1.3 When questions of accuracy between this test method
Fluids
and Test Method D2216 arise, Test Method D2216 shall be the
D2216 Test Methods for Laboratory Determination of Water
referee method.
(Moisture) Content of Soil and Rock by Mass
1.4 This test method is applicable for most soil types. For
D3740 Practice for Minimum Requirements for Agencies
some soils, such as those containing significant amounts of
Engaged in Testing and/or Inspection of Soil and Rock as
halloysite, mica, montmorillonite, gypsum or other hydrated
Used in Engineering Design and Construction
materials, highly organic soils, or soils in which the pore water
D4753 Guide for Evaluating, Selecting, and Specifying Bal-
contains dissolved solids (such as salt in the case of marine
ances and Standard Masses for Use in Soil, Rock, and
deposits), this test method may not yield reliable water content
Construction Materials Testing
values.
D6026 Practice for Using Significant Digits in Geotechnical
1.5 The values stated in SI units are to be regarded as the Data
standard. No other units of measurement are included in this
test method.
3. Terminology
1.6 RefertoPracticeD6026forguidanceconcerningtheuse 3.1 Definitions:
of significant figures. This is especially important if the water
3.1.1 All definitions are in accordance with Terminology
content will be used to calculate other relationships such as
D653.
moist mass to dry mass or vice versa, wet unit weight to dry
3.2 Definitions of Terms Specific to This Standard:
unit weight or vice versa, and total density to dry density or
3.2.1 microwave heating—a process by which heat is in-
vice versa. For example, if four significant digits are required
duced within a material due to the interaction between dipolar
in any of the above calculations, then the water content has to
molecules of the material and an alternating, high frequency
be recorded to the nearest 0.1 %. This occurs since 1 plus the
electric field. Microwaves are electromagnetic waves with 1
water content (not in percent) will have four significant digits
mm to 1 m wavelengths.
regardless of what the value of the water content is; that is, 1
3.2.2 water (moisture) content—the ratio, expressed as a
plus 0.1/100 = 1.001, a value with four significant digits.
percentage, of the mass of “pore” or “free” water in a given
While, if three significant digits are acceptable, then the water
mass of soil to the mass of the solid particles.
content can be recorded to the nearest 1 %.
1
ThistestmethodisunderthejurisdictionofASTMCommitteeD18onSoiland
2
Rock and is the direct responsibility of Subcommittee D18.08 on Special and For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Construction Control Tests. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Current edition approved Jan. 1, 2008. Published February 2008. Originally Standards volume information, refer to the standard’s Document Summary page on
approved in 1987. Last previous edition approved in 2000 as D4643 – 00. the ASTM website. DOI: 10.1520/D4643-08.
*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
1
---------------------- Page: 1 ----------------------
D4643 − 08
4. Summary of Test Method 6. Apparatus
6.1 Microwave Oven—Amicrowaveoven,preferablywitha
4.1 A moist soil specimen is placed in a suitable container
ventedchamber,issuitable.Therequiredsizeandpowerra
...
This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:D4643–00 Designation:D4643–08
Standard Test Method for
Determination of Water (Moisture) Content of Soil by the
1
Microwave Oven Heating
This standard is issued under the fixed designation D 4643; 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 (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope*
1.1 This test method outlines procedures for determining the water (moisture) content of soils by incrementally drying soil in
a microwave oven.
1.2This1.2 This test method can be used as a substitute forTest Method D 2216 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 Method D 2216 arise, Test Method D 2216 shall be the
referee method.
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 in which the pore water contains
dissolved solids (such as salt in the case of marine deposits), this test method may not yield reliable water content values.
1.5The values stated in SI units are to be regarded as the standard.
1.6
1.5 The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this test
method.
1.6 Refer to Practice D 6026 for guidance concerning the use of significant figures. This is especially important if the water
contentwillbeusedtocalculateotherrelationshipssuchasmoistmasstodrymassorviceversa,wetunitweighttodryunitweight
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 has to 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%.
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 health practices and determine the applicability of regulatory
limitations prior to use. See Section 7.
2. Referenced Documents
2
2.1 ASTM Standards:
D 653 Terminology Relating to Soil, Rock, and Contained Fluids
D 2216 Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass
D 3740 Practice for Minimum Requirements forAgencies Engaged in the Testing and/or Inspection of Soil and Rock as Used
in Engineering Design and Construction
D 4753Specification for Evaluating, Selecting, and Specifying Balances and Scales for Use in Testing Soil, Rock, and Related
2
Construction Materials Guide for Evaluating, Selecting, and Specifying Balances and Standard Masses for Use in Soil,
Rock, and Construction Materials Testing
D 6026 Practice for Using Significant Digits in Geotechnical Data
1
This test method is under the jurisdiction of ASTM Committee D-18D18 on Soil and Rock and is the direct responsibility of Subcommittee D18.08 on Special and
Construction Control Tests.
Current edition approved Feb. 10, 2000.Jan. 1, 2008. Published April 2000.February 2008. Originally published as D4643–87.approved in 1987. Last previous edition
D4643–93.approved in 2000 as D 4643 – 00.
2
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
, Vol 04.08.volume information, refer to the standard’s Document Summary page on the ASTM website.
*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.
1
---------------------- Page: 1 ----------------------
D4643–08
3. Terminology
3.1 Definitions:
3.1.1 All definitions are in accordance with Terminology D 653.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 microwave heating—aprocessbywhichheatisinducedwi
...
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