ASTM D4647-93(1998)e1
(Test Method)Standard Test Method for Identification and Classification of Dispersive Clay Soils by the Pinhole Test
Standard Test Method for Identification and Classification of Dispersive Clay Soils by the Pinhole Test
SCOPE
1.1 This test method presents a direct, qualitative measurement of the dispersibility and consequent colloidal erodibility of clay soils by causing water to flow through a small hole punched in a specimen. This test method is complemented by Test Method D4221.
1.2 This test method and the criteria for evaluating test data are based upon results of several hundred tests on samples collected from embankments, channels, and other areas where clay soils have eroded or resisted erosion in nature (1).
1.3 Three alternative procedures for classifying the dispersibility of clay soils are provided as follows:
1.3.1 Method A and Method C, adapted from Ref (1), classify soils into six categories of dispersiveness as: dispersibility (D1, D2), slight to moderately dispersive (ND4, ND3), and nondispersive (ND2, ND1).
1.3.2 Method B classifies soils into three categories of dispersiveness as:dispersibility (D), slightly dispersive (SD), and nondispersive (ND).
1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are provided for information only.
1.5 This standard does not purport to address all of the safety problems, 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.
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e1
Designation: D 4647 – 93 (Reapproved 1998)
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.
e NOTE—Keywords were added editorially December 1998
1. Scope Rammer and a 12-in. (305-mm) Drop
D 2216 Method for Laboratory Determination of Water
1.1 This test method presents a direct, qualitative measure-
(Moisture) Content of Soil, Rock, and Soil Aggregate
ment of the dispersibility and consequent colloidal erodibility
Mixtures
of clay soils by causing water to flow through a small hole
D 2487 Test Method for Classification of Soils for Engi-
punched in a specimen. This test method is complemented by
neering Purposes
Test Method D 4221.
D 2488 Practice for Description and Identification of Soils
1.2 This test method and the criteria for evaluating test data
(Visual-Manual Procedure)
are based upon results of several hundred tests on samples
D 3740 Practice for the Evaluation of Agencies in the
collected from embankments, channels, and other areas where
Testing and/or Inspection of Soil and Rock as Used In
clay soils have eroded or resisted erosion in nature (1).
Engineering Design and Construction
1.3 Three alternative procedures for classifying the dispers-
D 4221 Test Method for Dispersive Characteristics of Clay
ibility of clay soils are provided as follows:
Soil By Double Hydrometer
1.3.1 Method A and Method C, adapted from Ref (1),
D 4318 Test Method for Liquid Limit, Plastic Limit, and
classify soils into six categories of dispersiveness as: dispers-
Plasticity Index of Soils
ibility (D1, D2), slight to moderately dispersive (ND4, ND3),
D 4753 Specification for Evaluating, Selecting, and Speci-
and nondispersive (ND2, ND1).
fying Balances and Scales for Use in Soil, Rock and
1.3.2 Method B classifies soils into three categories of
Construction Materials Testing
dispersiveness as: dispersibility (D), slightly dispersive (SD),
and nondispersive (ND).
3. Terminology
1.4 The values stated in SI units are to be regarded as the
3.1 Definitions of Terms Specific to This Standard:
standard. The values given in parentheses are provided for
3.1.1 dispersive clays—clays that diaggregate easily and
information only.
rapidly in water of low-salt concentration, and without signifi-
1.5 This standard does not purport to address all of the
cant mechanical assistance. Such clays usually have a high
safety concerns, if any, associated with its use. It is the
proportion of their adsorptive capacity saturated with sodium
responsibility of the user of this standard to establish appro-
cations.
priate safety and health practices and determine the applica-
3.1.1.1 Discussion—Such clays generally have a high
bility of regulatory limitations prior to use.
shrink-swellpotential,havelowresistancetoerosion,andhave
2. Referenced Documents low permeability in an intact state.
2.1 ASTM Standards:
4. Summary of Test Method
D 422 Method for Particle Size Analysis of Soils
4.1 The test method is started with distilled water flowing
D 698 Test Method for Moisture-Density Relations of Soils
horizontally under a hydraulic head of 50 mm (2 in.) through
and Soil-Aggregate Mixtures Using a 5.5-lb (2.49-kg)
a 1.0-mm (0.04-in.) diameter hole punched in the soil speci-
men. The nature of the solution emerging from the specimen
This test method is under the jurisdiction of ASTM Committee D-18 on Soil under the intial 50-mm (2-in.) head provides the principle
and Rock and is the direct responsibility of Subcommittee D18.06 on Physico-
differentiation between dispersive and nondispersive clays.
Chemical Properties of Soils and Rock.
Flow from dispersive clays will be distinctly dark and the hole
Current edition approved Sept. 15, 1993. Published November 1993. Originally
through the specimen will enlarge rapidly, with a resultant
published as D 4647 – 87. Last previous edition D 4647 – 87.
The boldface numbers in parentheses refer to the list of references at the end of
increase in the flow rate. Flow from slightly to moderately
this test method.
Annual Book of ASTM Standards, Vol 04.08.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 4647
dispersive clays will be slightly dark with a constant hole size cost-benefit relationships in projects where public safety is not
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
NOTE 1—Notwithstanding the statement on precision and bias con-
pinhole test and other indirect tests on hundreds of samples
tained in this test method: The precision of this test method is dependent
indicates that the results of the pinhole test have the best
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
Practice D 3740 does not in itself assure reliable testing. Reliable testing
evaluation of cloudiness of effluent, final size of the pinhole,
depends on several factors; Practice D 3740 provides a means of evalu-
and computation of flow rates through the pinhole in order to
ating some of those factors.
classify the dispersive characteristics of the soil. Method B
requires only the evaluation of the cloudiness of effluent and
6. Limitations
finalsizeofthepinholetoclassifythedispersivecharacteristics
6.1 Development of the test procedure to provide reproduc-
of the soil. The computation of flow rates through the pinhole
ible results that differentiate between clay soils that were
in Method A serves primarily as a guide to the proper
known to be erodible (dispersive) and nonerodible (nondisper-
equipment and specimen performance under sequential pres-
sive) in the field indicates the following limitations in the use
sures applied during the test. All methods produce similar
of this test:
resultsandanymethodcanbeusedtoidentifydispersiveclays.
6.1.1 This test method is not applicable to soils with less
5.4 The use of Method A or Method C results in the
than 12 % fraction finer than 0.005 mm and with a plasticity
accumulation of data relative to sequential flow rates through
index less than or equal to 4 (2, 11). Such soils generally have
the pinhole and consequent enlargement or erosion of the hole.
low resistance to erosion regardless of dispersive characteris-
The pinhole erosion test was developed for the purpose of
tics.
identifying dispersive soils and is not intended to be a
6.1.2 The most consistent results are produced when the
geometrically scaled model of a prototype structure. Since the
natural water content of the sample is preserved during the
theory of similitude was not used in the design of the pinhole
sampling, shipping, storage, and testing operations.
test, quantitative data are not obtained. The quantity of flow
through the pinhole, amount of soil erosion, or the rate of soil 6.1.3 A few instances have been reported in which the
pinhole test did not identify some dispersive clays in which the
erosion should not be extrapolated to actual field conditions
(3). However, such data may be useful in performing qualita- porewatercontainedlessthan0.4meq/Ltotalsolublesaltsthat
were more than 80 % sodium salts.
tive evaluations of the consequences of such erosion in terms
of dam failure, loss of life and property.They also may be used 6.1.4 This test method was developed to test specimens of
in considering the cost effectiveness of defensive design disturbedsoilthatarecompactedintothetestcylinder.Thistest
measures necessary to minimize the effects of failure due to method also can be used to test undisturbed specimens when
dispersive clays. For example, the amount of colloidal erosion they are properly trimmed and sealed into the test cylinder;
that will occur in a soil classed as ND2 (very slightly however, some investigators (6) have found that this test
dispersive) will be very small for a relatively long period of method is not applicable in evaluating the dispersive charac-
time. Such erosion may not be significant in evaluating the teristics of undisturbed samples of highly sensitive clays. Such
D 4647
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-mL capac-
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 5 D1, D2, ND4;
75-mm (2.5 to 3-in.) punch. (No. 19 veterinarian hypodermic
SD 5 ND3; and ND 5 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-in.) head. 8.8 Stop Watch, reading to 0.1 s.
FIG. 1 Schematic Drawing of the Pinhole Test Equipment
D 4647
containers (plast
...
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