ASTM D4829-21

Standard Test Method for Expansion Index of Soils

SIGNIFICANCE AND USE
5.1 The expansion index, EI, value is used by engineers and other professionals as an indicator of the soil’s swelling potential. It may also be used to determine the suitability of a soil to satisfy requirements set by specifying agencies.  
5.2 The EI test is not used to duplicate any particular field conditions such as soil density, water content, loading, in-place soil structure, or soil water chemistry. However, consistent test conditions are used in preparation of compacted specimens such that direct correlation of data can be made.  
5.3 Based on experience with expansive soils, the recommended qualitative classification of potential expansion in a soil based on EI is provided in Table 1.  
5.4 The measurement of the magnitude of one-dimensional wetting-induced swell or collapse (hydrocompression) under different vertical (axial) pressures, as well as the magnitude of swell pressure and the magnitude of free swell, and also the determination of data for stress-induced compression following wetting-induced swell or collapse are covered by Test Methods D4546. The ability to test intact specimens for measuring one-dimensional wetting-induced swell or collapse is also covered in Methods D4546.
Note 1: The quality of the result produced by this standard is dependent on the competence of the personnel performing it and the suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objective testing/sampling/inspection/etc. Users of this standard are cautioned that compliance with Practice D3740 does not in itself assure reliable results. Reliable results depend on many factors; Practice D3740 provides a means of evaluating some of those factors.
SCOPE
1.1 This test method allows for determination of expansion potential of soils when inundated with distilled water.2 This test method measures a qualitative index property of the soil rather than a design parameter to be used for calculation of the actual amount of expansion. The expansion index, EI, provides an indication of swelling potential of a soil.  
1.2 This test method provides a simple, yet sensitive, method for evaluation of expansion potential of soils for practical engineering applications using an index parameter.  
1.3 Units—The values stated in SI units are to be regarded as standard. The values given in parentheses are provided for information only and are not considered standard. Reporting of test results in units other than SI shall not be regarded as nonconformance with this standard.  
1.3.1 The gravitational system of inch-pound units is used when dealing with inch-pound units. In the system, the pound (lbf) represents a unit of force (weight), while the units for mass is slugs. The slug unit is not given, unless dynamic (F = ma) calculations are involved.  
1.3.2 The SI units presented for apparatus are substitutions of the inch-pound units, other similar SI units should be acceptable providing they meet the technical requirements established by the inch-pound apparatus.  
1.3.3 It is common practice in the engineering/construction profession to concurrently use pounds to represent both a unit of mass (lbm) and of force (lbf). This practice implicitly combines two separate systems of units; the absolute and the gravitational systems. It is scientifically undesirable to combine the use of two separate sets of inch-pound units within a single standard. As stated, this standard includes the gravitational system of inch-pound units and does not use/present the slug unit of mass. However, the use of balances and scales recording pounds of mass (lbm) or recording density in lbm/ft3 shall not be regarded as nonconformance with this standard.  
1.3.4 The terms density and unit weight are often used interchangeably. Density is mass per unit volume, whereas unit weight is force per unit volume. In this standard, density is given o...

General Information

• Status: Published
• Publication Date: 31-Dec-2020
• ICS: 93.020 - Earthworks. Excavations. Foundation construction. Underground works
• Technical Committee: D18 - Soil and Rock
• Drafting Committee: D18.05 - Strength and Compressibility of Soils

Relations

• Refers: ASTM D4753-24 - Standard Guide for Evaluating, Selecting, and Specifying Balances and Standard Masses for Use in Soil, Rock, and Construction Materials Testing
• Effective Date: 01-Feb-2024
• Refers: ASTM D854-23 - Standard Test Methods for Specific Gravity of Soil Solids by the Water Displacement Method
• Effective Date: 01-Nov-2023
• Refers: ASTM D3740-23 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Nov-2023
• Refers: ASTM D3740-19 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Oct-2019
• Refers: ASTM D2216-19 - Standard Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass
• Effective Date: 01-Mar-2019
• Refers: ASTM D4753-15 - Standard Guide for Evaluating, Selecting, and Specifying Balances and Standard Masses for Use in Soil, Rock, and Construction Materials Testing
• Effective Date: 01-May-2015
• Refers: ASTM D653-14 - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 01-Aug-2014
• Refers: ASTM D4546-14 - Standard Test Methods for One-Dimensional Swell or Collapse of Soils
• Effective Date: 01-Mar-2014
• Refers: ASTM E11-13 - Standard Specification for Woven Wire Test Sieve Cloth and Test Sieves
• Effective Date: 01-Oct-2013
• Refers: ASTM D698-12 - Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Standard Effort (12 400 ft-lbf/ft³ (600 kN-m/m³))
• Effective Date: 01-May-2012
• Refers: ASTM D698-12e1 - Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Standard Effort (12 400 ft-lbf/ft³ (600 kN-m/m³))
• Effective Date: 01-May-2012
• Refers: ASTM D3740-12a - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-May-2012
• Refers: ASTM D3740-12 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Mar-2012
• Refers: ASTM D653-11 - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 01-Sep-2011
• Refers: ASTM D3740-11 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Sep-2011

Overview

ASTM D4829-21 is the Standard Test Method for Expansion Index (EI) of Soils, published by ASTM International. This method provides procedures for determining the expansion potential of soils-an essential factor for evaluating the suitability of soils for construction and engineering applications. The expansion index is a qualitative index property that helps engineers identify soils with swelling potential when exposed to water. This information is widely used in geotechnical investigations, site assessments, and compliance with construction requirements set by specifying agencies.

Key Topics

• Expansion Index (EI): The EI value is used as an indicator of the swelling potential of soils, which can impact the stability and performance of structures such as foundations, roads, and pavements.
• Test Procedure: The method involves preparing a representative soil sample, adjusting moisture content, compacting it into a specified mold, applying a controlled vertical stress, inundating it with distilled water, and measuring the vertical deformation over a 24-hour period.
• Classification of Soils: The standard provides a qualitative classification of soils based on the EI value, typically ranging from very low to very high potential for expansion.
• Use of Standardized Conditions: Although the test does not duplicate in-situ conditions (such as actual field densities or water contents), its consistent laboratory conditions allow for direct data comparison and correlation.

Applications

• Engineering Design: The expansion index is crucial in the design and construction of structures on or within expansive soils. It aids in the selection of proper foundation types, earthworks, and other site preparations to mitigate risks associated with soil swelling.
• Site Suitability Assessment: The EI test helps determining if soil at a proposed construction site meets regulatory or project requirements, preventing structural damage due to soil movement.
• Quality Assurance: By providing a consistent laboratory method, ASTM D4829-21 supports quality control during soil testing, facilitating reliable data for engineers and regulatory authorities.
• Risk Mitigation: Early identification of expansive soils can guide project planning and the implementation of soil stabilization techniques or selection of alternative construction sites.

Related Standards

• ASTM D4546 - Test methods for measuring one-dimensional swell or collapse of soils, including swell pressure and hydrocompression.
• ASTM D3740 - Practice for minimum requirements for agencies performing soil and rock testing, ensuring reliable data and competent personnel.
• ASTM D2216 - Methods for the determination of water (moisture) content in soil and rock.
• ASTM D698 - Laboratory compaction characteristics of soil using standard energy effort.
• ASTM D653, D854, D2435, D4753, D6026, E11 - A range of supporting standards covering terminology, specific gravity, consolidation properties, equipment calibration, and data accuracy.

Practical Value

By following ASTM D4829-21, professionals in geotechnical engineering, construction, and regulatory agencies can reliably evaluate and compare the swelling potential of soils. This standard test method enhances project safety, performance, and compliance with industry best practices by providing a simple yet sensitive index for expansion potential. Proper implementation of this method enables informed decision-making in construction projects, minimizing costly repairs and structural failures linked to expansive soils.

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Keywords: ASTM D4829-21, Expansion Index, soils, swelling potential, expansive soils, geotechnical engineering, laboratory test, construction site assessment, soil classification, soil testing standards

Standards Content (Sample)

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.
Designation:D4829 −21
Standard Test Method for
Expansion Index of Soils
This standard is issued under the fixed designation D4829; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* recordingpoundsofmass(lbm)orrecordingdensityinlbm/ft
shall not be regarded as nonconformance with this standard.
1.1 This test method allows for determination of expansion
1.3.4 The terms density and unit weight are often used
potentialofsoilswheninundatedwithdistilledwater. Thistest
interchangeably.Densityismassperunitvolume,whereasunit
method measures a qualitative index property of the soil rather
weight is force per unit volume. In this standard, density is
than a design parameter to be used for calculation of the actual
given only in SI units. After the density has been determined,
amount of expansion. The expansion index, EI, provides an
the unit weight is calculated in SI or inch-pound units, or both.
indication of swelling potential of a soil.
1.4 All observed and calculated values shall conform to the
1.2 This test method provides a simple, yet sensitive,
guidelines for significant digits and rounding established in
method for evaluation of expansion potential of soils for
Practice D6026, unless superseded by this test method.
practical engineering applications using an index parameter.
1.4.1 For purposes of comparing a measured or calculated
1.3 Units—The values stated in SI units are to be regarded
value(s) with specified limits, the measured or calculated
as standard. The values given in parentheses are provided for
value(s) shall be rounded to the nearest decimal of significant
informationonlyandarenotconsideredstandard.Reportingof
digits in the specified limit.
test results in units other than SI shall not be regarded as
1.4.2 Theproceduresusedtospecifyhowdataarecollected/
nonconformance with this standard.
recorded or calculated in the standard are regarded as the
1.3.1 The gravitational system of inch-pound units is used
industry standard. In addition, they are representative of the
when dealing with inch-pound units. In the system, the pound
significant digits that generally should be retained. The proce-
(lbf) represents a unit of force (weight), while the units for
dures used do not consider material variation, purpose for
mass is slugs. The slug unit is not given, unless dynamic (F =
obtaining the data, special purpose studies, or any consider-
ma) calculations are involved.
ations for the user’s objectives; and it is common practice to
1.3.2 The SI units presented for apparatus are substitutions
increase or reduce significant digits of reported data to be
of the inch-pound units, other similar SI units should be
commensuratewiththeseconsiderations.Itisbeyondthescope
acceptable providing they meet the technical requirements
of this standard to consider significant digits used in analysis
established by the inch-pound apparatus.
methods for engineering data.
1.3.3 It is common practice in the engineering/construction
profession to concurrently use pounds to represent both a unit
1.5 The text of this standard references notes and footnotes
of mass (lbm) and of force (lbf). This practice implicitly
that provide explanatory material. These notes and footnotes
combines two separate systems of units; the absolute and the
(excluding those in tables and figures) shall not be considered
gravitational systems. It is scientifically undesirable to com-
as requirements of the standard.
bine the use of two separate sets of inch-pound units within a
1.6 This standard does not purport to address all of the
single standard. As stated, this standard includes the gravita-
safety concerns, if any, associated with its use. It is the
tional system of inch-pound units and does not use/present the
responsibility of the user of this standard to establish appro-
slug unit of mass. However, the use of balances and scales
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
ThistestmethodisunderthejurisdictionofASTMCommitteeD18onSoiland
1.7 This international standard was developed in accor-
Rock and is the direct responsibility of Subcommittee D18.05 on Strength and
dance with internationally recognized principles on standard-
Compressibility of Soils.
Current edition approved Jan. 1, 2021. Published January 2021. Originally
ization established in the Decision on Principles for the
approved in 1995. Last previous edition approved in 2019 as D4829–19. DOI:
Development of International Standards, Guides and Recom-
10.1520/D4829-21.
2 mendations issued by the World Trade Organization Technical
Anderson, J. N., and Lade, P. V., “The Expansion Index Test,” Geotechnical
Testing Journal, Vol 4, No. 2, ASTM, 1981, pp. 58–67. Barriers to Trade (TBT) Committee.
*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
D4829−21
2. Referenced Documents 5. Significance and Use
2.1 ASTM Standards: 5.1 Theexpansionindex, EI,valueisusedbyengineersand
D653Terminology Relating to Soil, Rock, and Contained other professionals as an indicator of the soil’s swelling
Fluids potential. It may also be used to determine the suitability of a
D698Test Methods for Laboratory Compaction Character- soil to satisfy requirements set by specifying agencies.
istics of Soil Using Standard Effort (12,400 ft-lbf/ft (600
5.2 The EI test is not used to duplicate any particular field
kN-m/m ))
conditionssuchassoildensity,watercontent,loading,in-place
D854Test Methods for Specific Gravity of Soil Solids by
soil structure, or soil water chemistry. However, consistent test
Water Pycnometer
conditions are used in preparation of compacted specimens
D2216Test Methods for Laboratory Determination ofWater
such that direct correlation of data can be made.
(Moisture) Content of Soil and Rock by Mass
5.3 Based on experience with expansive soils, the recom-
D2435/D2435MTest Methods for One-Dimensional Con-
mended qualitative classification of potential expansion in a
solidation Properties of Soils Using Incremental Loading
soil based on EI is provided in Table 1.
D3740Practice for Minimum Requirements for Agencies
Engaged in Testing and/or Inspection of Soil and Rock as 5.4 The measurement of the magnitude of one-dimensional
Used in Engineering Design and Construction
wetting-induced swell or collapse (hydrocompression) under
D4546Test Methods for One-Dimensional Swell or Col- different vertical (axial) pressures, as well as the magnitude of
lapse of Soils
swell pressure and the magnitude of free swell, and also the
D4753Guide for Evaluating, Selecting, and Specifying Bal- determinationofdataforstress-inducedcompressionfollowing
ances and Standard Masses for Use in Soil, Rock, and
wetting-inducedswellorcollapsearecoveredbyTestMethods
Construction Materials Testing D4546. The ability to test intact specimens for measuring
D6026Practice for Using Significant Digits in Geotechnical
one-dimensional wetting-induced swell or collapse is also
Data covered in Methods D4546.
E11Specification forWovenWireTest Sieve Cloth andTest NOTE 1—The quality of the result produced by this standard is
dependent on the competence of the personnel performing it and the
Sieves
suitability of the equipment and facilities used. Agencies that meet the
criteria of Practice D3740 are generally considered capable of competent
3. Terminology
and objective testing/sampling/inspection/etc. Users of this standard are
cautioned that compliance with Practice D3740 does not in itself assure
3.1 Definitions:
reliable results. Reliable results depend on many factors; Practice D3740
3.1.1 Fordefinitionsofcommontechnicaltermsusedinthis
provides a means of evaluating some of those factors.
standard, refer to Terminology D653.
3.1.2 scarification—scratching the surface of a compacted
6. Apparatus
layertofacilitatebondingwiththenextlayertoavoidpotential
6.1 Mold—The mold shall be cylindrical in shape, made of
separation between compacted layers.
metal, and shall have the dimensions indicated in Fig. 1. The
mold shall have a metal, detachable collar inscribed with a
4. Summary of Test Method
mark 50.8 mm (2.00 in.) above the base. The lower section of
4.1 Asample is processed to obtain a representative sample
the mold is designed to retain a removable stainless steel ring.
that is then separated over a 4.75 mm (No. 4) sieve. Distilled
The dimensions shown in Fig. 1 are necessary to properly
water is added and thoroughly mixed with the soil passing the
manufacture the mold. Laboratories are not expected to have
separationsieve(testspecimen).Awatercontentisdetermined
the capability to confirm these dimensions. See Section 9 for
and the soil is allowed to stand (cure) for 16 h before it is
items needing verification.
compacted into a specimen ring. The degree of saturation is
6.1.1 Specimen Ring—A stainless steel ring that is 25.4 6
calculated and must be 50 6 2% before proceeding with
0.2 mm (1.0 6 0.01 in.) in height, 101.9 6 0.1 mm (4.010 6
testing. A new test specimen is made if the saturation doesn’t
0.005 in.) in internal diameter, and not less than 3.05 mm
meet the criteria. Several trials may occur before the necessary
(0.120 in.) in wall thickness. This ring is designed to fit inside
degreeofsaturationisachieved.Onceachieved,thecompacted
the mold.
specimenisplacedinaloadingdevice.Heightanddeformation
6.2 Rammer—Ametalrammer,eithermanuallyormechani-
readings are taken prior to applying a vertical stress of 6.9 kPa
callyoperated,thatshallfallfreelythroughadistanceof305 6
(1 lbf/in. ) on the specimen. After 10 min, the specimen is
2 mm (12.0 6 0.1 in.) from the surface of the specimen. The
inundated with distilled water and deformation readings are
taken at specific time intervals for 24 h or until the rate of
expansionbecomeslessthan0.005mm/h(0.0002in./h).Atthe TABLE 1 Classification of Potential Expansion of Soils Based on
EI
end of the test, final height and deformation readings are taken
Expansion Index, EI Potential
and the expansion index is calculated.
Expansion
0–20 Very Low
21–50 Low
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
51–90 Medium
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
91–130 High
Standards volume information, refer to the standard’s Document Summary page on >130 Very High
the ASTM website.
D4829−21
A
Dimensional Equivalents
Letter in. mm
ID Diameter 4.010 ± 0.005 101.9 ± 0.1
OD Diameter 6.00 ± 0.01 152.4 ± 0.2
H 0.50±0.01 12.7±0.2
7 1
D (Hole) ⁄32 ± ⁄64 5.5±0.4
U 1.625±0.01 41.3±0.2
T 0.325 - 0.375 8.25 - 9.50
O 0.125 ± 0.005 3.2 ± 0.1
R 1.00±0.01 25.4±0.2
W 0.563 ± 0.004 14.3 ± 0.1
V 0.688±0.01 17.5±0.2
L (ring wall thickness) $0.120 $3.05
A
The SI units presented are basically substitutions of the inch-pound units; other
rationalized SI units should be acceptable providing they meet the technical
requirements established by the inch-pound apparatus.
FIG. 1 Mold with Ring for Compaction of Specimen
rammer shall be equipped with a suitable arrangement to 6.6 Separation Sieves—A 4.75-mm (No. 4) sieve conform-
control the drop height. The weight of the hammer shall be ing to the requirements of Specification E11. This sieve is
24.47 6 0.09 N (5.50 6 0.02 lbf, or mass of 2.495 6 0.009 subjecttoroughoperationandshallnotbeusedforquantitative
kg). The striking face of the rammer shall be planar and grain size analysis.
circularwithadiameterwhennewof50.80 60.13mm(2.000
6.7 Mixing Tools—Miscellaneoustoolssuchasmixingpans,
60.005in.)Ifusingamanualrammerwithaguidesleeve,the
spoons, trowels, spatulas, a spray bottle, a suitable manual or
rammer shall meet the requirements described inTest Methods
mechanical mixer, and so forth.
D698 for a manual rammer. If using a mechanical rammer, the
circular face rammer shall meet the requirements described in
6.8 Specimen Height Measurement Device—A device used
Test Methods D698.
to measure the height of the specimen with a readability to
0.025mm(0.001in.)orbetter.Thedeviceshallbeconstructed
6.3 Balance—Balancesshallconformtotherequirementsof
such that its use will not disturb/deform, indent, or penetrate
Guide D4753 and calibrated in accordance with the interval
the specimen.
given in Practice D3740.
6.3.1 Abalance having a minimum capacity of 1000 g with
6.9 Loading Device—A consolidometer or equivalent load-
a readability without estimation of 0.1 g for use when deter-
ing device as described in Test Methods D2435/D2435M.
mining masses not related to water content determination. For
6.10 Porous Disks—The disks shall be smooth ground and
water content determinations, the balance shall have a mini-
fine enough (Note 2) to reduce or prevent intrusion of soil into
mumcapacityof100gwithareadabilitywithoutestimationof
the disks. The disks shall have a close fit to the specimen ring
0.01 g.
to avoid extrusion or punching. Refer to the apparatus section
6.4 Drying Oven—A vented, thermostatically controlled
of Test Methods D2435/D2435M for further details on the
oven capable of maintaining a uniform temperature of 110 6
porous disks. The disks shall reduce false displacements
5°C (230 6 9°F) throughout the drying chamber.
caused by seating of the specimen against the surface of the
disk.Suchdisplacementsaresignificant,especiallyifdisplace-
6.5 Straightedge—A stiff metal straight edge, preferably
ments and applied vertical pressures are small.
steel,ofanyconvenientlengthbutnotlessthan150mm(6in.).
Oneedgeofthestraightedgeshallbebeveled.Thestraightedge
NOTE 2—A suitable pore size is 10 µm. Experience has shown that
must be machined straight to a tolerance of 60.1 mm (60.005
suitable disk dimensions are 12.7 mm 6 0.13 mm (0.50 in. 6 0.005 in.)
in.). in height and 101.5 mm 6 0.13 mm (3.995 in. 6 0.005 in.) in diameter.
D4829−21
6.11 Deformation Indicator—A mechanical or digital dial 8. Test Specimen Preparation
indicator, displacement transducer, or equivalent with a read-
8.1 Place the soil passing the separation sieve in a pan or
ability of 0.025 mm (0.001 in.) or better.
bowl. Based on the mass of the soil, its water content, and the
6.12 Miscellaneous Items—Distilled water, knife, pan,
estimated water content needed to achieve a degree of satura-
bowl, spray bottle, and tare cans are useful. tion of 50 6 2% in the compacted condition, calculate the
amount of distilled water to add.
7. Sampling
8.2 Use a spray bottle filled with distilled water to evenly
7.1 This test method does not address, in any detail,
distribute the calculated amount of distilled water needed.
procurement of the sample. It is assumed the sample is Thenmixthoroughlytoachieveauniformwatercontent.After
obtainedusingappropriatemethodsandisrepresentativeofthe
mixing, take 100 g or more of soil for a water content
soil under evaluation. Preserve the sample at its original determination. Follow the procedure given in Test Methods
moisture condition and at no time shall the sample be allowed
D2216, with the exception for the minimum mass of the
toundergoundesirabletemperaturechangessuchasfreezingor specimen as stated above. Determine and record the necessary
heating.
massesforthewatercontenttothenearest0.01g.Immediately
after taking soil for the water content determination, place the
7.2 The soil should not be excessively wet or dry, unless
remainingsoilinatightlysealedcontainerandallowittostand
received in the dry state, during processing. If the sample is
(cure) for a period of at least 16 h.
excessively wet, allow the sample to air dry (Note 3) until the
8.2.1 Determine and record the water content, w, to the
surface of the soil looks slightly wet but there are no signs of
nearest 0.1% in accordance with Test Method D2216.
free water exiting the soil. Then, thoroughly mix the sample.
Using miniature stockpiling or quartering, obtain a represen-
8.3 Determineandrecordthemassofthespecimenring, M ,
r
tative sample that will yield 1 kg (2.2 lbm) or more of soil
to the nearest 1 g. Assemble the mold and the specimen ring
passing the 4.75 mm (No. 4) sieve. Determine and record the
and prepare to compact the specimen. Compact the specimen
mass of the representative sample, M, to the nearest 1 g.
t
inthemoldintwoequallayerstogiveatotalcompacteddepth
NOTE 3—Air drying ca
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM 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: D4829 − 19 D4829 − 21
Standard Test Method for
Expansion Index of Soils
This standard is issued under the fixed designation D4829; 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 allows for determination of expansion potential of soils when inundated with distilled water. This test
method measures a qualitative index property of the soil rather than a design parameter to be used for calculation of the actual
amount of expansion. The expansion index, EI, provides an indication of swelling potential of a soil.
1.2 This test method provides a simple, yet sensitive, method for evaluation of expansion potential of soils for practical
engineering applications using an index parameter.
1.3 Units—The values stated in SI units are to be regarded as standard. The values given in parentheses are provided for
information only and are not considered standard. Reporting of test results in units other than SI shall not be regarded as
nonconformance with this standard.
1.3.1 The gravitational system of inch-pound units is used when dealing with inch-pound units. In the system, the pound (lbf)
represents a unit of force (weight), while the units for mass is slugs. The slug unit is not given, unless dynamic (F = ma)
calculations are involved.
1.3.2 The SI units presented for apparatus are substitutions of the inch-pound units, other similar SI units should be acceptable
providing they meet the technical requirements established by the inch-pound apparatus.
1.3.3 It is common practice in the engineering/construction profession to concurrently use pounds to represent both a unit of mass
(lbm) and of force (lbf). This practice implicitly combines two separate systems of units; the absolute and the gravitational systems.
It is scientifically undesirable to combine the use of two separate sets of inch-pound units within a single standard. As stated, this
standard includes the gravitational system of inch-pound units and does not use/present the slug unit of mass. However, the use
of balances and scales recording pounds of mass (lbm) or recording density in lbm/ft shall not be regarded as nonconformance
with this standard.
1.3.4 The terms density and unit weight are often used interchangeably. Density is mass per unit volume, whereas unit weight is
force per unit volume. In this standard, density is given only in SI units. After the density has been determined, the unit weight
is calculated in SI or inch-pound units, or both.
1.4 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice
D6026, unless superseded by this test method.
This test method is under the jurisdiction of ASTM Committee D18 on Soil and Rock and is the direct responsibility of Subcommittee D18.05 on Strength and
Compressibility of Soils.
Current edition approved Sept. 1, 2019Jan. 1, 2021. Published September 2019January 2021. Originally approved in 1995. Last previous edition approved in 20112019
as D4829–11.–19. DOI: 10.1520/D4829-19.10.1520/D4829-21.
Anderson, J. N., and Lade, P. V., “The Expansion Index Test,” Geotechnical Testing Journal, Vol 4, No. 2, ASTM, 1981, pp. 58–67.
*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
D4829 − 21
1.4.1 For purposes of comparing a measured or calculated value(s) with specified limits, the measured or calculated value(s) shall
be rounded to the nearest decimal of significant digits in the specified limit.
1.4.2 The procedures used to specify how data are collected/recorded or calculated in the 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 data.
1.5 The text of this standard references notes and footnotes that provide explanatory material. These notes and footnotes
(excluding those in tables and figures) shall not be considered as requirements of the standard.
1.6 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, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.7 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
3 3
D698 Test Methods for Laboratory Compaction Characteristics of Soil Using Standard Effort (12,400 ft-lbf/ft (600 kN-m/m ))
D854 Test Methods for Specific Gravity of Soil Solids by Water Pycnometer
D2216 Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass
D2435D2435/D2435M Test Methods for One-Dimensional Consolidation Properties of Soils Using Incremental Loading
D3740 Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in
Engineering Design and Construction
D4546 Test Methods for One-Dimensional Swell or Collapse of Soils
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 in Geotechnical Data
E11 Specification for Woven Wire Test Sieve Cloth and Test Sieves
3. Terminology
3.1 Definitions:
3.1.1 For definitions of common technical terms used in this standard, refer to Terminology D653.
3.1.2 scarification—scratching the surface of a compacted layer to facilitate bonding with the next layer to avoid potential
separation between compacted layers.
4. Summary of Test Method
4.1 A sample is processed to obtain a representative sample that is then separated over a 4.75 mm (No. 4) sieve. Distilled water
is added and thoroughly mixed with the soil passing the separation sieve (test specimen). A water content is determined and the
soil is allowed to stand (cure) for 16 h before it is compacted into a specimen ring. The degree of saturation is calculated and must
be 50 6 2 % before proceeding with testing. A new test specimen is made if the saturation doesn’t meet the criteria. Several trials
may occur before the necessary degree of saturation is achieved. Once achieved, the compacted specimen is placed in a loading
device. Height and deformation readings are taken prior to applying a vertical stress of 6.9 kPa (1 lbf/in. ) on the specimen. After
10 min, the specimen is inundated with distilled water and deformation readings are taken at specific time intervals for 24 h or
until the rate of expansion becomes less than 0.005 mm/h (0.0002 in./h). At the end of the test, final height and deformation
readings are taken and the expansion index is calculated.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
D4829 − 21
5. Significance and Use
5.1 The expansion index, EI, value is used by engineers and other professionals as an indicator of the soil’s swelling potential.
It may also be used to determine the suitability of a soil to satisfy requirements set by specifying agencies.
5.2 The EI test is not used to duplicate any particular field conditions such as soil density, water content, loading, in-place soil
structure, or soil water chemistry. However, consistent test conditions are used in preparation of compacted specimens such that
direct correlation of data can be made.
5.3 Based on experience with expansive soils, the recommended qualitative classification of potential expansion in a soil based
on EI is provided in Table 1.
5.4 The measurement of the magnitude of one-dimensional wetting-induced swell or collapse (hydrocompression) under different
vertical (axial) pressures, as well as the magnitude of swell pressure and the magnitude of free swell, and also the determination
of data for stress-induced compression following wetting-induced swell or collapse are covered by Test Methods D4546. The
ability to test intact specimens for measuring one-dimensional wetting-induced swell or collapse is also covered in Methods
D4546.
NOTE 1—The quality of the result produced by this standard is dependent on the competence of the personnel performing it and the suitability of the
equipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objective
testing/sampling/inspection/etc. Users of this standard are cautioned that compliance with Practice D3740 does not in itself assure reliable results. Reliable
results depend on many factors; Practice D3740 provides a means of evaluating some of those factors.
6. Apparatus
6.1 Mold—The mold shall be cylindrical in shape, made of metal, and shall have the dimensions indicated in Fig. 1. The mold
shall have a metal, detachable collar inscribed with a mark 50.8 mm (2.00 in.) above the base. The lower section of the mold is
designed to retain a removable stainless steel ring. The dimensions shown in Fig. 1 are necessary to properly manufacture the mold.
Laboratories are not expected to have the capability to confirm these dimensions. See Section 9 for items needing verification.
6.1.1 Specimen Ring—A stainless steel ring that is 25.4 6 0.2 mm (1.0 6 0.01 in.) in height, 101.9 6 0.1 mm (4.010 6 0.005
in.) in internal diameter, and not less than 3.05 mm (0.120 in.) in wall thickness. This ring is designed to fit inside the mold.
6.2 Rammer—A metal rammer, either manually or mechanically operated, that shall fall freely through a distance of 305 6 2 mm
(12.0 6 0.1 in.) from the surface of the specimen. The rammer shall be equipped with a suitable arrangement to control the drop
height. The weight of the hammer shall be 24.47 6 0.09 N (5.50 6 0.02 lbf, or mass of 2.495 6 0.009 kg). The striking face of
the rammer shall be planar and circular with a diameter when new of 50.80 6 0.13 mm (2.000 6 0.005 in.) If using a manual
rammer with a guide sleeve, the rammer shall meet the requirements described in Test Methods D698 for a manual rammer. If using
a mechanical rammer, the circular face rammer shall meet the requirements described in Test Methods D698.
6.3 Balance—Balances shall conform to the requirements of Guide D4753 and calibrated in accordance with the interval given
in Practice D3740.
6.3.1 A balance having a minimum capacity of 1000 g with a readability without estimation of 0.1 g for use when determining
masses not related to water content determination. For water content determinations, the balance shall have a minimum capacity
of 100 g with a readability without estimation of 0.01 g.
TABLE 1 Classification of Potential Expansion of Soils Based on
EI
Expansion Index, EI Potential
Expansion
0–20 Very Low
21–50 Low
51–90 Medium
91–130 High
>130 Very High
D4829 − 21
A
Dimensional Equivalents
Letter in. mm
ID Diameter 4.010 ± 0.005 101.9 ± 0.1
OD Diameter 6.00 ± 0.01 152.4 ± 0.2
H 0.50 ± 0.01 12.7 ± 0.2
7 1
D (Hole) ⁄32 ± ⁄64 5.5 ± 0.4
U 1.625 ± 0.01 41.3 ± 0.2
T 0.325 - 0.375 8.25 - 9.50
O 0.125 ± 0.005 3.2 ± 0.1
R 1.00 ± 0.01 25.4 ± 0.2
W 0.563 ± 0.004 14.3 ± 0.1
V 0.688 ± 0.01 17.5 ± 0.2
L (ring wall thickness) $0.120 $3.05
A
The SI units presented are basically substitutions of the inch-pound units; other
rationalized SI units should be acceptable providing they meet the technical
requirements established by the inch-pound apparatus.
FIG. 1 Mold with Ring for Compaction of Specimen
6.4 Drying Oven—A vented, thermostatically controlled oven capable of maintaining a uniform temperature of 110 6 5°C (230
6 9°F) throughout the drying chamber.
6.5 Straightedge—A stiff metal straight edge, preferably steel, of any convenient length but not less than 150 mm (6 in.). One edge
of the straightedge shall be beveled. The straightedge must be machined straight to a tolerance of 60.1 mm (60.005 in.).
6.6 Separation Sieves—A 4.75-mm (No. 4) sieve conforming to the requirements of Specification E11. This sieve is subject to
rough operation and shall not be used for quantitative grain size analysis.
6.7 Mixing Tools—Miscellaneous tools such as mixing pans, spoons, trowels, spatulas, a spray bottle, a suitable manual or
mechanical mixer, and so forth.
6.8 Specimen Height Measurement Device—A device used to measure the height of the specimen with a readability to 0.025 mm
(0.001 in.) or better. The device shall be constructed such that its use will not disturb/deform, indent, or penetrate the specimen.
6.9 Loading Device—A consolidometer or equivalent loading device as described in Test Methods D2435D2435/D2435M.
6.10 Porous Disks—The disks shall be smooth ground and fine enough (Note 2) to reduce or prevent intrusion of soil into the
disks. The disks shall have a close fit to the specimen ring to avoid extrusion or punching. Refer to the apparatus section of Test
Methods D2435D2435/D2435M for further details on the porous disks. The disks shall reduce false displacements caused by
seating of the specimen against the surface of the disk. Such displacements are significant, especially if displacements and applied
vertical pressures are small.
NOTE 2—A suitable pore size is 10 μm. Experience has shown that suitable disk dimensions are 12.7 mm 6 0.13 mm (0.50 in. 6 0.005 in.) in height
and 101.5 mm 6 0.13 mm (3.995 in. 6 0.005 in.) in diameter.
D4829 − 21
6.11 Deformation Indicator—A mechanical or digital dial indicator, displacement transducer, or equivalent with a readability of
0.025 mm (0.001 in.) or better.
6.12 Miscellaneous Items—Distilled water, knife, pan, bowl, spray bottle, and tare cans are useful.
7. Sampling
7.1 This test method does not address, in any detail, procurement of the sample. It is assumed the sample is obtained using
appropriate methods and is representative of the soil under evaluation. Preserve the sample at its original moisture condition and
at no time shall the sample be allowed to undergo undesirable temperature changes such as freezing or heating.
7.2 The soil should not be excessively wet or dry, unless received in the dry state, during processing. If the sample is excessively
wet, allow the sample to air dry (Note 3) until the surface of the soil looks slightly wet but there are no signs of free water exiting
the soil. Then, thoroughly mix the sample. Using miniature stockpiling or quartering, obtain a representative sample that will yield
1 kg (2.2 lbm) or more of soil passing the 4.75 mm (No. 4) sieve. Determine and record the mass of the representative sample,
M , to the nearest 1 g.
t
NOTE 3—Air drying causes irreversible changes to some clay particles that cause permanent flocculations and decreases the fine fraction.
7.3 If the representative sample contains particles larger than the 4.75 mm (No. 4) sieve, separate the soil using the separation
sieve. Determine and record the mass of the soil retained, M , on the 4.75 mm (No. 4) separation sieve to the nearest 1 g.
cf
Determine and record the percent retained on the separation sieve of the representative sample to the nearest 1 %.
7.3.1 If the particles retained on the separation sieve are aggregations and not individual particles, thoroughly break up the
aggregations in a manner such that the natural size of individual particles is not reduced. If particles larger than 4.75 mm are
potentially expansive, such as claystone, shale, or weathered volcanic rock, they may be broken down to pass the 4.75 mm (No.
4) sieve if these particles are being evaluated and are consistent with the intended use of the soil. Determine and record the mass
of soil retained, M , on the 4.75 mm (No. 4) sieve after breaking apart any aggregations or larger particles of interest to the nearest
cfa
1 g. Record on the data sheet if particles were broken down and included that otherwise would not have been. D
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