ASTM D4647-93(2006)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D 4647 – 93 (Reapproved 2006)
Standard Test Method for
Identification and Classification of Dispersive Clay Soils by
the Pinhole Test
This standard is issued under the fixed designation D 4647; 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.
1. Scope D 698 Test Methods for Laboratory Compaction Character-
istics of Soil Using Standard Effort (12,400 ft-lbf/ft (600
1.1 This test method presents a direct, qualitative measure-
kN-m/m ))
ment of the dispersibility and consequent colloidal erodibility
D 2216 Test Methods for Laboratory Determination of Wa-
of clay soils by causing water to flow through a small hole
ter (Moisture) Content of Soil and Rock by Mass
punched in a specimen. This test method is complemented by
D 2487 Practice for Classification of Soils for Engineering
Test Method D 4221.
Purposes (Unified Soil Classification System)
1.2 This test method and the criteria for evaluating test data
D 2488 Practice for Description and Identification of Soils
are based upon results of several hundred tests on samples
(Visual-Manual Procedure)
collected from embankments, channels, and other areas where
2 D 3740 Practice for Minimum Requirements for Agencies
clay soils have eroded or resisted erosion in nature (1).
Engaged in the Testing and/or Inspection of Soil and Rock
1.3 Three alternative procedures for classifying the dispers-
as Used in Engineering Design and Construction
ibility of clay soils are provided as follows:
D 4221 Test Method for Dispersive Characteristics of Clay
1.3.1 Method A and Method C, adapted from Ref (1),
Soil by Double Hydrometer
classify soils into six categories of dispersiveness as: dispers-
D 4318 Test Methods for Liquid Limit, Plastic Limit, and
ibility (D1, D2), slight to moderately dispersive (ND4, ND3),
Plasticity Index of Soils
and nondispersive (ND2, ND1).
D 4753 Guide for Evaluating, Selecting, and Specifying
1.3.2 Method B classifies soils into three categories of
Balances and Standard Masses for Use in Soil, Rock, and
dispersiveness as: dispersibility (D), slightly dispersive (SD),
Construction Materials Testing
and nondispersive (ND).
1.4 The values stated in SI units are to be regarded as the
3. Terminology
standard. The values given in parentheses are provided for
3.1 Definitions of Terms Specific to This Standard:
information only.
3.1.1 dispersive clays—clays that diaggregate easily and
1.5 This standard does not purport to address all of the
rapidly in water of low-salt concentration, and without signifi-
safety concerns, if any, associated with its use. It is the
cant mechanical assistance. Such clays usually have a high
responsibility of the user of this standard to establish appro-
proportion of their adsorptive capacity saturated with sodium
priate safety and health practices and determine the applica-
cations.
bility of regulatory limitations prior to use.
3.1.1.1 Discussion—Such clays generally have a high
2. Referenced Documents shrink-swellpotential,havelowresistancetoerosion,andhave
3 low permeability in an intact state.
2.1 ASTM Standards:
D 422 Test Method for Particle-Size Analysis of Soils
4. Summary of Test Method
4.1 The test method is started with distilled water flowing
horizontally under a hydraulic head of 50 mm (2 in.) through
ThistestmethodisunderthejurisdictionofASTMCommitteeD18onSoiland
Rock and is the direct responsibility of Subcommittee D18.06 on Physico-Chemical a 1.0-mm (0.04-in.) diameter hole punched in the soil speci-
Properties of Soils and Rock.
men. The nature of the solution emerging from the specimen
Current edition approved Jan. 1, 2006. Published February 2006. Originally
under the intial 50-mm (2-in.) head provides the principle
e1
approved in 1987. Last previous edition approved in 1998 as D 4647 – 93(1998) .
differentiation between dispersive and nondispersive clays.
The boldface numbers in parentheses refer to the list of references at the end of
this test method.
Flow from dispersive clays will be distinctly dark and the hole
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
through the specimen will enlarge rapidly, with a resultant
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
increase in the flow rate. Flow from slightly to moderately
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. dispersive clays will be slightly dark with a constant hole size
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 4647 – 93 (2006)
and flow rate. Flow from nondispersive clays will be com- involved or where normal maintenance procedures will handle
pletely clear with no measurable increase in the hole size. the problem. In such cases, classifying the soil as ND (nondis-
4.2 Test results are evaluated from the appearance of the persive) using Method B of the pinhole test should be
flowing solution emerging from the specimen, the rate of flow, adequate.
and the final size of the hole through the specimen. These
5.5 Pinhole tests that result in classifying soil as slightly
observations provide the basis for classifying the soil speci-
dispersive (ND3 by Method A or Method C or SD by Method
men.
B) indicate high uncertainty about the existence of significant
problems to be considered in the design or stability of a
5. Significance and Use
structure. In such cases, it is advisable to resample and test a
5.1 The pinhole test provides one method of identifying the
number of other soils from the same area to generate an
dispersive characteristics of clay soils that are to be or have
adequate statistical sample for problem evaluation. The origi-
been used in earth construction. The piping failures of a
nal slightly dispersive sample may come from an area on the
number of homogeneous earth dams, erosion along channel or
edge of a more highly dispersive soil.
canal banks, and rainfall erosion of earthen structures have
5.6 In a few physiographic areas or geoclimatic conditions,
been attributed to the colloidal erosion along cracks or other
or both, neither the pinhole test nor the other indicator tests
flow channels formed in masses of dispersive clay (2).
provide consistent identification of dispersive clays (5, 6, 7).In
5.2 This test method models the action of water flowing
such cases, the results of the tests (8, 9) should be evaluated in
along a crack in an earth embankment. Other indirect tests,
terms of cost effectiveness and design judgment (7).
such as the double hydrometer test (Test Method D 4221), the
5.7 For some projects, it may be desirable to perform the
crumb test (3, 4), that relates the turbidity of a cloud of
pinhole test using eroding fluids other than distilled water (8,
suspended clay colloids as an indicator of the clay dispersivity,
10). In such cases, MethodA, Method B, or Method C may be
and chemical tests that relate the percentage of sodium to total
used to identify the dispersive characteristics of the soil and
soluble salt content of the soil are also used as indicator tests
compare the results with those obtained using distilled water.
of clay dispersibility (2). The comparison of results from the
pinhole test and other indirect tests on hundreds of samples
NOTE 1—Notwithstanding the statement on precision and bias con-
indicates that the results of the pinhole test have the best tained in this test method: The precision of this test method is dependent
onthecompetenceofthepersonnelperformingit,andthesuitabilityofthe
correlation with the erosional performance of clay soils in
equipmentandfacilitiesused.AgencieswhichmeetthecriteriaofPractice
nature.
D 3740 are generally considered capable of competent and objective
5.3 Method A and Method C of the pinhole test require the
testing. Users of this test method are cautioned that compliance with
evaluation of cloudiness of effluent, final size of the pinhole,
Practice D 3740 does not in itself assure reliable testing. Reliable testing
and computation of flow rates through the pinhole in order to
depends on several factors; Practice D 3740 provides a means of evalu-
classify the dispersive characteristics of the soil. Method B
ating some of those factors.
requires only the evaluation of the cloudiness of effluent and
finalsizeofthepinholetoclassifythedispersivecharacteristics 6. Limitations
of the soil. The computation of flow rates through the pinhole
6.1 Development of the test procedure to provide reproduc-
in Method A serves primarily as a guide to the proper
ible results that differentiate between clay soils that were
equipment and specimen performance under sequential pres-
known to be erodible (dispersive) and nonerodible (nondisper-
sures applied during the test. All methods produce similar
sive) in the field indicates the following limitations in the use
resultsandanymethodcanbeusedtoidentifydispersiveclays.
of this test:
5.4 The use of Method A or Method C results in the
6.1.1 This test method is not applicable to soils with less
accumulation of data relative to sequential flow rates through
than 12 % fraction finer than 0.005 mm and with a plasticity
the pinhole and consequent enlargement or erosion of the hole.
index less than or equal to 4 (2, 11). Such soils generally have
The pinhole erosion test was developed for the purpose of
low resistance to erosion regardless of dispersive characteris-
identifying dispersive soils and is not intended to be a
tics.
geometrically scaled model of a prototype structure. Since the
6.1.2 The most consistent results are produced when the
theory of similitude was not used in the design of the pinhole
natural water content of the sample is preserved during the
test, quantitative data are not obtained. The quantity of flow
sampling, shipping, storage, and testing operations.
through the pinhole, amount of soil erosion, or the rate of soil
6.1.3 A few instances have been reported in which the
erosion should not be extrapolated to actual field conditions
pinhole test did not identify some dispersive clays in which the
(3). However, such data may be useful in performing qualita-
porewatercontainedlessthan0.4meq/Ltotalsolublesaltsthat
tive evaluations of the consequences of such erosion in terms
were more than 80 % sodium salts.
of dam failure, loss of life and property.They also may be used
in considering the cost effectiveness of defensive design 6.1.4 This test method was developed to test specimens of
measures necessary to minimize the effects of failure due to disturbedsoilthatarecompactedintothetestcylinder.Thistest
dispersive clays. For example, the amount of colloidal erosion method also can be used to test undisturbed specimens when
that will occur in a soil classed as ND2 (very slightly they are properly trimmed and sealed into the test cylinder;
dispersive) will be very small for a relatively long period of however, some investigators (6) have found that this test
time. Such erosion may not be significant in evaluating the method is not applicable in evaluating the dispersive charac-
cost-benefit relationships in projects where public safety is not teristics of undisturbed samples of highly sensitive clays. Such
D 4647 – 93 (2006)
clays may be classed as dispersive from the pinhole test results 8. Apparatus
but perform as nondispersive materials in nature.
8.1 Pinhole Test Apparatus—Typical pinhole test apparatus
6.1.5 This test method is performed with distilled water, at
is shown in Fig. 1, Fig. 2, and Fig. 3. Various other types and
a pH of 5.5 to 7.0, as the eroding fluid. The use of water with
sizes of specimen molds or containers and top and base plates
various ionic concentrations and combinations will alter the
may be used provided the test specimen is 38 mm (1.5 in.)
results of the test (8, 10).
long, the pinhole is 1.0 mm (0.04 in.) in diameter, and the hole
through the truncated cone centering guide or other centering
7. Classification
device is 1.5 mm (0.059 in.) in diameter.
7.1 The observations of this test method provide the basis
8.1.1 It is important that the outlet drain be large enough to
for classifying the soil specimen into a category of dispersive-
accommodate the maximum inflow without creating a partial
ness according to the following general criteria:
vacuuminthesystem.Partialvacuummaydevelopwhensmall
7.1.1 Method A:
diameter outlet drains flow at full capacity and when long
D1, D2—Dispersive clays that fail rapidly under 50-mm
segments of flexible tubing are attached to the outflow pipe.
(2-in.) head.
8.1.2 The development of partial vacuum in the system
ND4, ND3—Slightly to moderately dispersive clays that
produces hydraulic heads greater than those specified for the
erode slowly under 50-mm (2-in.) or 180-mm (7-in.) head.
test in Section 10 and following.
ND2, ND1—Nondispersive clay with very slight to no
1 1
8.1.3 The installation of a 1.6-mm ( ⁄16-in.) to 3-mm ( ⁄8-in.)
colloidal erosion under 380-mm (15-in.) or 1020-mm (40-in.)
diameter breather hole in the center of the base plate, as shown
head.
in Fig. 1, generally assures discharge from the system at
7.1.2 Method B:
atmospheric pressure without partial vacuum.
D—Dispersive clays that erode rapidly under 50-mm (2-in.)
8.2 Constant Head Tank, to supply distilled water with a pH
head.
of 5.5 to 7.0.
SD—Slightly dispersive clays that erode slowly under
8.3 Graduated Cylinders, of 10, 25, 50, and 100-mLcapac-
180-mm (7-in.) head.
ity.
ND—Nondispersive clays that show very slight or no
8.4 Wire Screen, with holes smaller than 2 mm (0.08 in.),
colloidal erosion under 380-mm (15-in.) head.
cut in circular shape to fit inside the specimen tube.
NOTE 2—Method B for classifying dispersiveness of clay soils com-
8.5 Wire Punch, 1.0 mm (0.039 in.) in diameter by 50 to
bines the categories of Method A as follows: D = D1, D2, ND4;
75-mm (2.5 to 3-in.) punch. (No. 19 veterinarian hypodermic
SD = ND3; and ND = ND2, ND1.
needle or 1-mm drill bit or stiff wire length.)
7.1.3 Method C:
8.6 Centering Guide—Truncated cone centering guide with
D1, D2—Dispersive clays that fail rapidly under 50-mm
1.5-mm (0.059-in.) diameter hole (plastic, brass, steel, or other
(2-in.) head.
suitable material).
ND4, ND3—Dispersive clays that erode slowly under
8.7 Coarse Sand, that has been washed and sieved through
50-mm (2-in.), 180-mm (7-in.), or 380-mm (15-in.) head.
No. 10 to ⁄4-in. sieves (2 to 6 mm in diameter).
ND2, ND1—Nondispersive clay with very slight to no
colloidal erosion under 380-mm (15-i
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