ASTM D4404-84(1998)e1
(Test Method)Standard Test Method for Determination of Pore Volume and Pore Volume Distribution of Soil and Rock by Mercury Intrusion Porosimetry
Standard Test Method for Determination of Pore Volume and Pore Volume Distribution of Soil and Rock by Mercury Intrusion Porosimetry
SCOPE
1.1 This test method covers the determination of the pore volume and the pore volume distributions of soil and rock by the mercury intrusion porosimetry method. The range of apparent diameters of pores for which this test method is applicable is fixed by the operant pressure range of the testing instrument. This range is typically between apparent pore entrance diameters of about 100 [mu]m and 2.5 nm (0.0025 [mu]m). Larger pores must be measured by another method.
1.2 Mercury intrusion porosimetry is useful only for measuring pores open to the outside of a soil or rock fragment; mercury intrusion porosimetry will not give the volume of any pores completely enclosed by surrounding solids. This test method will give only the volume of intrudable pores that have an apparent diameter corresponding to a pressure within the pressurizing range of the testing instrument.
1.3 The intrusion process proceeds from the outside of a fragment toward its center. Comparatively large interior pores can exist that have smaller pores as the only means of access. Mercury intrusion porosimetry will incorrectly register the entire volume of these "ink-bottle" pores as having the apparent diameter of the smaller access pores. In a test sample, inter-fragment pores can exist in addition to intra-fragment pores (see Section 3 for definitions). The inter-fragment pores will vary in size and volume depending on the size and shape of the soil or rock fragments and on the manner in which the fragments are packed together. It is possible that some inter-fragment pores can have the same apparent diameter as some intra-fragment pores. When this occurs this test method cannot distinguish between them. Thus, the test method yields an intruded pore volume distribution that is in part dependent upon the packing of multifragment samples. However, most soils and rocks have intra-fragment pores much smaller than the inter-fragment pores. This situation leads to a bi-modal pore size distribution and the distinction between the two classes of pores can then be made (see Figs. 1 and 2).
1.4 Mercury intrusion may involve the application of high pressures to the sample. This may result in a temporary, or permanent, or temporary and permanent alteration in the pore geometry. Generally, soils and rocks are composed of comparatively strong solids and are less subject to these alterations than certain other materials. However, the possibility remains that the use of this test method may alter the natural pore volume distribution that is being measured.
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 consult and establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific precaution statements, see Section 8.
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e1
Designation: D 4404 – 84 (Reapproved 1998)
Standard Test Method for
Determination of Pore Volume and Pore Volume Distribution
of Soil and Rock by Mercury Intrusion Porosimetry
This standard is issued under the fixed designation D 4404; 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 in December 1998.
1. Scope 1.4 Mercury intrusion may involve the application of high
pressures to the sample. This may result in a temporary, or
1.1 This test method covers the determination of the pore
permanent, or temporary and permanent alteration in the pore
volume and the pore volume distributions of soil and rock by
geometry. Generally, soils and rocks are composed of com-
the mercury intrusion porosimetry method. The range of
paratively strong solids and are less subject to these alterations
apparent diameters of pores for which this test method is
than certain other materials. However, the possibility remains
applicable is fixed by the operant pressure range of the testing
that the use of this test method may alter the natural pore
instrument. This range is typically between apparent pore
volume distribution that is being measured.
entrance diameters of about 100 μm and 2.5 nm (0.0025 μm).
1.5 This standard does not purport to address all of the
Larger pores must be measured by another method.
safety concerns, if any, associated with its use. It is the
1.2 Mercury intrusion porosimetry is useful only for mea-
responsibility of the user of this standard to consult and
suring pores open to the outside of a soil or rock fragment;
establish appropriate safety and health practices and deter-
mercury intrusion porosimetry will not give the volume of any
mine the applicability of regulatory limitations prior to use.
pores completely enclosed by surrounding solids. This test
For specific precaution statements, see Section 8.
method will give only the volume of intrudable pores that have
an apparent diameter corresponding to a pressure within the
2. Referenced Documents
pressurizing range of the testing instrument.
2.1 ASTM Standards:
1.3 The intrusion process proceeds from the outside of a
C 699 Methods for Chemical, Mass Spectrometric, and
fragment toward its center. Comparatively large interior pores
Spectrochemical Analysis of, and Physical Tests on, Be-
can exist that have smaller pores as the only means of access.
ryllium Oxide Powder
Mercury intrusion porosimetry will incorrectly register the
entire volume of these “ink-bottle” pores as having the
3. Terminology
apparent diameter of the smaller access pores. In a test sample,
3.1 Definitions:
inter-fragment pores can exist in addition to intra-fragment
3.1.1 apparent pore diameter—the diameter of a pore that is
pores (see Section 3 for definitions). The inter-fragment pores
assumed to be cylindrical and that is intruded at a pressure, P,
will vary in size and volume depending on the size and shape
given by the equation in 4.1.
of the soil or rock fragments and on the manner in which the
3.1.2 inter-fragment pores—those pores between fragments
fragments are packed together. It is possible that some inter-
when they are packed together and that are intruded during the
fragment pores can have the same apparent diameter as some
test.
intra-fragment pores. When this occurs this test method cannot
3.1.3 intra-fragment pores—those pores lying within the
distinguish between them. Thus, the test method yields an
exterior outlines of the individual soil and rock fragments.
intruded pore volume distribution that is in part dependent
3.1.4 intruded pore volume—the corrected volume of mer-
upon the packing of multifragment samples. However, most
cury intruded during the test.
soils and rocks have intra-fragment pores much smaller than
the inter-fragment pores. This situation leads to a bi-modal
4. Summary of Test Method
pore size distribution and the distinction between the two
4.1 When a liquid does not wet a porous solid, it will not
classes of pores can then be made (see Fig. 1 and Fig. 2).
enter the pores in the solid by capillary action. The non-wetting
liquid (mercury in this test method) can be forced into the pores
by the application of external pressure. The size of the pores
This test method is under the jurisdiction of ASTM Committee D-18 on Soil
and Rock and is the direct responsibility of Subcommittee D18.14 on Geotechnics
of Waste Management.
Current edition approved Aug. 31, 1984. Published October 1984. Annual Book of ASTM Standards, Vol 12.01.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 4404
FIG. 1 Example of Cumulative Pore Volume Distribution Plot
that are intruded is inversely proportional to the applied surrounding the test specimen with mercury at a low pressure,
pressure. When a cylindrical pore model is assumed, the a pressure generator to cause intrusion, pressure transducers,
relationship between pressure and size is given as follows: capable of measuring the intruding pressure with an accuracy
of at least 61 % throughout the range of pressures over which
d 524g~cosu!/P (1)
the pores of interest are being intruded, and a means of
where: measuring intruded mercury volumes to an accuracy of at least
3 −3 3
d 5 apparent pore diameter being intruded,
61mm (610 cm ).
g5 surface tension of the mercury,
6.2 Vacuum Pump, if not part of the porosimeter, to evacuate
u5 contact angle between the mercury and the pore wall,
the sample holder.
−7
and
6.3 Analytical Balance, with an accuracy of at least 610
P 5 absolute pressure causing the intrusion.
kg (60.1 mg).
Any set of convenient and compatible units may be used.
4.2 The volume of the intruded pores is determined by
7. Reagent
measuring the volume of mercury forced into them at various
7.1 Triple-Distilled Mercury.
pressures. A single determination involves increasing the
pressure, either continuously or step-wise, and recording the
8. Safety Precautions
measured intruded volume at various pressures.
8.1 Mercury is a hazardous substance that can cause illness
and death. Store mercury in closed containers to control its
5. Significance and Use
evaporation and use only in well ventilated rooms. Mercury
5.1 This test method is intended for use in determining the
can also be absorbed through the skin so avoid direct contact.
volume and the volume distribution of pores in soil and rock
Wash hands immediately after any operation involving mer-
with respect to the apparent diameter of the entrances of the
cury; the use of gloves is advocated. Exercise extreme care to
pores. In general, both the size and volume of the pores affects
avoid spilling mercury. Clean up any spills immediately using
the soil or rock performance. Thus, the pore volume distribu-
procedures recommended explicitly for mercury. Handle in-
tion is useful in understanding soil and rock performance and
truded samples with great care and dispose of in a safe and
in identifying a material that can beexpected to perform in a
environmentally acceptable manner immediately after comple-
particular manner (1, 2).
tion of the test.
6. Apparatus
9. Sampling, Test Specimens, and Test Units
6.1 Mercury Intrusion Porosimeter— This shall be
9.1 The material from which the test sample is drawn shall
equipped with a sample holder capable of containing one or
be representative of the soil or rock. The test sample shall be as
several soil or rock fragments. This sample holder is frequently
large as practicable considering the test apparatus.
called a penetrometer. The porosimeter shall have a means of
NOTE 1—Sample size is limited by the pore-measuring capacity of the
penetrometer, which is currently (1984) slightly more than 1 cm . The
small sample size may prevent the measurement of porosity represented
The boldface numbers in parentheses refer to the list of references appended to
this standard. by relatively large cracks and fissures in the material. Judgement is
D 4404
FIG. 2 Example of Differential Pore Volume Distribution Plot
required in the application of these measurements to the characterization
11.4 Place the penetrometer containing the sample in the
of the soil or rock masses.
appropriate chamber of the porosimeter, following the manu-
facturer’s instructions, and evacuate to a pressure of at least 1.3
10. Conditioning
Pa (10 μmHg).
10.1 The ideal preconditioning for the test specimen is an 11.5 Fill the penetrometer with mercury, in accordance with
the manufacturer’s instructions, by pressurizing to some suit-
outgassing or drying procedure that removes all foreign sub-
ably low pressure.
stances from the pores and pore walls of the soil or rock and
does not alter the soil or rock in any way. If possible, the
NOTE 3—The pressure required to fill the penetrometer with mercury is
appropriate combination of temperature and pressure and the
also capable of intruding sufficiently large pores of both the inter- and
required time of conditioning shall be experimentally deter-
intra-fragment classes. Thus, the process can intrude some pores and the
mined for the specific soil or rock under test. This outgassing volume distribution of these pores cannot subsequently be determined.
This fact should be recognized, and where possible, a filling pressure
or drying technique shall then be the one specified and used.
should be selected that will not intrude pores in the diameter range of
10.2 Where the procedure described in 10.1 is not practical,
interest.
rock or coarse-grained soil without fines shall be outgassed in
11.6 Place the filled penetrometer in the pressure vessel of
a vacuum at at least 1.3 Pa (10 μmHg) and at a temperature of
the porosimeter and prepare the instrument for pressurization
150°C for at least 24 h. Soil containing any plastic fines
and intrusion readings in accordance with the manufacturer’s
requires special drying procedures to avoid alteration of pore
instructions.
structure. Freeze drying has been successfully employed (3, 4)
11.7 Raise the pressure, either continuously or incremen-
and is a simple procedure. Critical region drying may also be
tally, and record both the absolute pressure and the volume of
used (5), but is more complex and expensive than freeze
intruded mercury until the maximum pressure of interest is
drying.
reached.
11. Procedure
NOTE 4—When raising the pressure incrementally, the pressure shall be
maintained during the pause and not allowed to decrease.
11.1 Outgas or dry the test specimen in accordance with
NOTE 5—When testing some materials, the time required to achieve
10.1 or 10.2.
intrusion equilibrium will not be the same at all pressures. Often the
11.2 Weigh the outgassed or dried specimen and record this
equilibrium time is appreciably longer at pressures that cause an abrupt
weight.
and large increase in intruded volume. Failure to record the equilibrium
intrusion may result in some of the pore volume being incorrectly assigned
11.3 Place the outgassed or dried material in the penetrom-
to smaller pore diameters. The extent to which this may be a problem can
eter.
be assessed by conducting two tests, each at a different pressure increase
rate, and comparing the results.
NOTE 2—When performing the operation described in 11.2 and 11.3,
the outgassed or dried material is exposed to the laboratory atmosphere NOTE 6—Use of the equation in 4.1 requires the absolute pressure, P.
and can readsorb vapors. Thus, this operation should be carried out as With some instruments it may not be possible to read the absolute pressure
rapidly as possible. directly. In this case the gage pressure shall be recorded at each step, and
D 4404
the absolute pressures subsequently calculated.
13.2.2 The contact angle enters the equation as a cosine
NOTE 7—The choice of pressure intervals at which data are to be
function, and it is more important to know the value of the
recorded is left to the judgment of the operator. Normally, at least 10 to 15
angle accurately for the material under test. The contact angle
intervals will be required to adequately define the pore volume distribu-
of mercury has been measured on a variety of solids by several
tion. In selecting these pressure intervals, a rough idea of the expected
different techniques; references to some of these measurements
distribution is helpful, since the pressure interval can be larger in regions
are given in Appendix X1. This appendix also lists references
where little or no intrusion occurs and should be smaller in regions where
for several methods of contact-angle measurement that have
a large volume of intrusion is expected. It is not necessary to continue the
process up to the maximum pressurizing capability of the instrument if all been found useful. The ideal value for reducing the data is the
of the pores of interest in a particular test specimen have been intruded at
one that has been determined for the material under test. If
a lesser pressure.
direct measurement is impractical, the use of an assumed value
is customary. If mercury intrusion is being used for the
11.8 Upon completion of the pressuring cycle, reduce the
comparison of similar materials for quality control purposes,
pressure and disassemble and clean the instrument in accor-
then an assumed value is satisfactory, however, when different
dance with the manufacturer’s instructions.
materials are being compared, the assumption of a single value
for the contact angle may lead to errors.
12. Blank Test for Corrections
13.3 The next step in the calculations is the correction of the
12.1 An intrusion test on a nonporous sample is required to
intruded volume readings. Corrections fall into two categories:
obtain values to use in correcting intrusion data for compress-
low-pressure corrections and high-pressure corrections.
ibilities and temperature changes.
13.3.1 Low-pressure corrections account for the fact that
12.2 Select a nonporous material that has approximately the
part of the apparent intrusion recorded at the lowest pressures
same compressibility and bulk volume as the soil or rock
is actually the compression of the air trapped in the penetrom-
sample that is to be tested.
eter when it was filled with mercury. This correction is
12.3 Test the nonporous sample in exactly the same manner
important only when the distribution of large pores must be
as outlined in Section 11. Raise the pressure in the same steps
meas
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