ASTM D6031-96(2004)
(Test Method)Standard Test Method for Logging In Situ Moisture Content and Density of Soil and Rock by the Nuclear Method in Horizontal, Slanted, and Vertical Access Tubes
Standard Test Method for Logging In Situ Moisture Content and Density of Soil and Rock by the Nuclear Method in Horizontal, Slanted, and Vertical Access Tubes
SIGNIFICANCE AND USE
This test method is useful as a repeatable, nondestructive technique to monitor in-place density and moisture of soil and rock along lengthy sections of horizontal, slanted, and vertical access holes or tubes. With proper calibration in accordance with Annex A1, this test method can be used to quantify changes in density and moisture content of soil and rock.
This test method is used in vadose zone monitoring, for performance assessment of engineered barriers at waste facilities, and for research related to monitoring the movement of liquids (water solutions and hydrocarbons) through soil and rock. The nondestructive nature of the test allows repetitive measurements at a site and statistical analysis of results.
The fundamental assumptions inherent in this test method are that the dry bulk density of the test material is constant and that the response to fast neutrons and gammaray energy associated with soil and liquid chemistry is constant.
SCOPE
1.1 This test method covers collection and comparison of logs of thermalized-neutron counts and back-scattered gamma counts along horizontal or vertical air-filled access tubes.
1.2 The in-situ water content in mass per unit volume and the density in mass per unit volume of soil and rock at positions or in intervals along the length of an access tube are calculated by comparing the thermal neutron count rate and gamma count rates respectively to previously established calibration data.
1.3 The values stated in SI units are regarded as the standard. The inch-pound units given in parentheses may be approximate and are provided for information only.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazards, see Section 6.
General Information
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Standards Content (Sample)
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Designation:D6031–96 (Reapproved 2004)
Standard Test Method for
Logging In Situ Moisture Content and Density of Soil and
Rock by the Nuclear Method in Horizontal, Slanted, and
Vertical Access Tubes
This standard is issued under the fixed designation D6031; 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 D2922 TestMethodsforDensityofSoilandSoil-Aggregate
in Place by Nuclear Methods (Shallow Depth)
1.1 This test method covers collection and comparison of
D2937 Test Method for Density of Soil in Place by the
logs of thermalized-neutron counts and back-scattered gamma
Drive-Cylinder Method
counts along horizontal or vertical air-filled access tubes.
D3017 Test Method for Water Content of Soil and Rock in
1.2 The in situ water content in mass per unit volume and
Place by Nuclear Methods (Shallow Depth)
thedensityinmassperunitvolumeofsoilandrockatpositions
D4428/D4428M Test Methods for Crosshole Seismic Test-
or in intervals along the length of an access tube are calculated
ing
by comparing the thermal neutron count rate and gamma count
D4564 Test Method for Density and Unit Weight of Soil in
rates respectively to previously established calibration data.
Place by the Sleeve Method
1.3 The values stated in SI units are regarded as the
D5195 Test Method for Density of Soil and Rock In-Place
standard. The inch-pound units given in parentheses may be
at Depths Below Surface by Nuclear Methods
approximate and are provided for information only.
D5220 TestMethodforWaterMassperUnitVolumeofSoil
1.4 This standard does not purport to address all of the
and Rock In-Place by the Neutron Depth Probe Method
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
3. Significance and Use
priate safety and health practices and determine the applica-
3.1 This test method is useful as a repeatable, nondestruc-
bility of regulatory limitations prior to use. For specific
tive technique to monitor in-place density and moisture of soil
hazards, see Section 6.
and rock along lengthy sections of horizontal, slanted, and
2. Referenced Documents vertical access holes or tubes. With proper calibration in
accordance with Annex A1, this test method can be used to
2.1 ASTM Standards:
quantify changes in density and moisture content of soil and
D1452 PracticeforSoilExplorationandSamplingbyAuger
rock.
Borings
3.2 This test method is used in vadose zone monitoring, for
D1586 Test Method for Penetration Test (SPT) and Split-
performance assessment of engineered barriers at waste facili-
Barrel Sampling of Soils
ties, and for research related to monitoring the movement of
D1587 Practice forThin-WalledTube Sampling of Soils for
liquids (water solutions and hydrocarbons) through soil and
Geotechnical Purposes
rock. The nondestructive nature of the test allows repetitive
D2113 Practice for Rock Core Drilling and Sampling of
measurements at a site and statistical analysis of results.
Rock for Site Investigation
3.3 The fundamental assumptions inherent in this test
D2216 Test Methods for Laboratory Determination of Wa-
method are that the dry bulk density of the test material is
ter (Moisture) Content of Soil and Rock by Mass
constant and that the response to fast neutrons and gammaray
energy associated with soil and liquid chemistry is constant.
ThistestmethodisunderthejurisdictionofASTMCommitteeD18onSoiland
4. Interferences
Rock and is the direct responsibility of Subcommittee D18.21 on GroundWater and
Vadose Zone Investigations.
4.1 The sample heterogeneity and chemical composition of
Current edition approved Nov. 1, 2004. Published December 2004. Originally
the material under test will affect the measurement of both
approved in 1996. Last previous edition approved in 1996 as D6031–96. DOI:
10.1520/D6031-96R04.
moisture and density.The apparatus should be calibrated to the
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on Withdrawn. The last approved version of this historical standard is referenced
the ASTM website. on www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D6031–96 (2004)
material under test at a similar density of dry soil or rock and establish conditions for a reproducible reference count rate. It
in the similar type and orientation of access tube, or adjust- also may serve as a radiation shield.
ments must be made in accordance with Annex A2. 5.2 Accessories shall include:
4.2 Hydrogen, in forms other than water, as defined by Test 5.2.1 AccessTubing—Theaccesstubing(casing)isrequired
for all access holes in nonlithified materials (soils and poorly
Method D2216, will cause measurements in excess of the true
moisture content. Some elements such as boron, chlorine, and consolidated rock) that cannot maintain constant borehole
diameter with repeated measurements. If access tubing is
minute quantities of cadmium, if present in the material under
test, will cause measurements lower than the true moisture required it must be of a material, such as aluminum, steel, or
plastic, having an interior diameter large enough to permit
content. Some elements with atomic numbers greater than 20
such as iron or other heavy metals may cause measurements probeaccesswithoutbinding,andanexteriordiameterassmall
higher than the true density value. as possible to provide close proximity of the material under
4.3 The measurement of moisture and density using this test test. The same type of tubing must be used in the field as is
used in calibration.
method exhibits spatial bias in that it is more sensitive to the
material closest to the access tube. The density and moisture 5.2.2 Hand Auger or Power Drilling/Trenching
Equipment—Equipmentthatcanbeusedtoestablishtheaccess
measurements are necessarily an average of the total sample
hole or position the access tube when required (see 5.2.1).Any
involved.
equipment that provides a suitable clean open hole for instal-
4.4 The sample volume for a moisture measurement is
3 3
lation of access tubing and insertion of the probe that ensures
approximately 0.11 m (3.8 ft ) at a moisture content of 200
the measurements are performed on undisturbed soil and rock
kg/m (12.5 lbf/ft ). The actual sample volume for moisture is
while maintaining a constant diameter per width shall be
indeterminate and varies with the apparatus and the moisture
acceptable. The type of equipment and methods of advancing
content of the material. In general the greater the moisture
the access hole should be reported.
content of the material, the smaller the measurement volume.
5.2.3 Winching Equipment or Other Motive Devices—
4.5 Adensitymeasurementhasasamplevolumeofapproxi-
3 3
Equipment that can be used to move the probe through the
mately 0.028 m (0.8 ft ). The actual sample volume for
access tubing. The type of such equipment is dependent upon
density is indeterminate and varies with the apparatus and the
theorientationoftheaccesstubingandthedistanceoverwhich
densityofthematerial.Ingeneral,thegreaterthedensityofthe
the probe must be moved.
material, the smaller the measurement volume.
4.6 Air gaps between the probe and the access tube or voids
6. Hazards
around the access tube will cause the indicated moisture
content and density to be less than the calibrated values.
NOTE 1—Warning: This equipment utilizes radioactive materials that
4.7 Condensed moisture inside the access tube may cause
may be hazardous to the health of the users unless proper precautions are
the indicated moisture content to be greater than the true
taken. Users of this equipment must become completely familiar with all
possible safety hazards and with all applicable regulations concerning the
moisture content of material outside the access tube.
handling and use of radioactive materials. Effective user instructions
together with routine safety procedures are a recommended part of the
5. Apparatus
operation of this apparatus.
5.1 While exact details of construction of the apparatus may
NOTE 2—Caution: When using winching or other motive equipment,
the user should take additional care to learn its proper use in conjunction
vary, the system shall consist of:
with measurement apparatus. Known safety hazards such as cutting and
5.1.1 Fast Neutron Source—A sealed mixture of a radioac-
pinching exist when using such equipment.
tive material such as americium or radium and a target material
NOTE 3—Thistestmethoddoesnotcoverallsafetyprecautions.Itisthe
such as beryllium, or other fast neutron sources such as
responsibility of the users to familiarize themselves with all safety
californium that do not require a target.
precautions.
5.1.2 Slow Neutron Detector—Any type of slow neutron
7. Calibration, Standardization, and Reference Check
detector, such as boron trifluoride or helium-3 proportional
counters.
7.1 Calibrate the instrument in accordance with Annex A1.
5.1.3 High-Energy Gamma-Radiation Source— A sealed
7.2 Adjust the calibration in accordance with Annex A2 if
source of radioactive material, such as cesium-137, cobalt-60,
adjustments are necessary.
or radium-226.
7.3 Standardization and Reference Check:
5.1.4 Gamma Detector—Any type of gamma detector, such
7.3.1 Nuclear apparatus are subject to the long-term decay
as a Geiger-Mueller tube.
of the radioactive source and aging of detectors and electronic
5.1.5 Suitable Readout Device:
systems that may change the relationship between count rate
5.1.6 Cylindrical Probe—The apparatus shall be equipped
and either the material density or the moisture content of the
with a cylindrical probe, containing the neutron and gamma material, or both. To correct for these changes, the apparatus
sources and the detectors, connected by a cable or cables of
may be calibrated periodically. To minimize error, moisture
sufficient design and length, that are capable of raising and and density measurements commonly are reported as count
lowering the probe in vertical applications and pulling it in
ratios, the ratio of the measured count rate to a count rate made
horizontal applications, to the desired measurement location. in a reference standard. The reference count rate should be
5.1.7 Reference Standard—A device containing dense, hy- similar or higher than the count rates over the useful measure-
drogenous material for checking equipment operation and to ment range of the apparatus.
D6031–96 (2004)
7.3.2 Standardization of equipment on the reference stan- toring for leak detection. Backfill should approximate the
dard is required at the start of each day’s use and a permanent composition, water content, and bulk density of test material as
nearly as possible.
record of these data shall be retained.The standardization shall
be performed with the equipment located at least 10 m (33 ft) 8.1.2 Grouting of annular spaces, if required, should be of
minimum functional thickness, and grout mixtures should not
away from other radioactive sources and large masses or other
contain excessive water. Grouts thicker than 5 cm (2 in.) create
items that may affect the reference count rate.
high background counts that will obscure moisture content
7.3.3 If recommended by the apparatus manufacturer to
changes in fine-textured soils and severely limit meaningful
provide more stable and consistent results, turn on the appara-
density measurements in all soil types. Grouting should not be
tus prior to use to allow it to stabilize and leave the power on
used unless it is required to seal off flow pathways along the
during the day’s testing.
access tube, such as in some vertical borings and where
7.3.4 Using the reference standard, take at least four repeti-
trenches cross engineered barriers. Grouting can be accom-
tivereadingsatthemanufacturer’srecommendedmeasurement
plished using procedures described in Test Methods D4428/
period of 20 or more at some shorter period and obtain the
D4428M.
mean. If available on the instrument, one measurement at a
8.1.3 Record and note the position of the ground water
period of four or more times the normal test measurement
table, perched water tables, and changes in soil texture as
period is acceptable. This constitutes one standardization
drilling or trenching progresses.
check.
8.1.4 If ground water is encountered or saturated conditions
7.3.5 If the value obtained in 7.3.4 is within the following
are expected to develop, seal the tube at seams and open ends
limits, the equipment is considered to be in satisfactory
to prevent water seepage into the tube. This will prevent
condition and the value may be used to determine the count
erroneous measurements and possible damage to the probe.
ratios for the day of use. If the value obtained is outside these
8.1.5 The access tube should project above the ground and
limits, another standardization check should be made. If the
be capped to prevent foreign material from entering. The
second standardization check is within the limits, the equip-
access tube should not project out of the test material far
ment may be used. If it also fails the test, however, the
enough to be damaged by equipment traffic.
equipmentshallbeadjustedorrepairedasrecommendedbythe
8.2 Pass a dummy probe through the access tube to verify
manufacturer.
proper clearance before deploying the radioactive sources.
8.3 Standardize the apparatus (see 7.3).
No No
No 1 2F . Ns . No 2 2F
Œ Œ
8.4 Proceed with the test run in a continuous logging mode
F F
or in a noncontinuous logging mode as follows:
where:
8.4.1 Set up the winching equipment or other motive
Ns = value of current standardization check (7.3.4)onthe
devices (see 5.2.3) to begin a logging run by stationing the
reference standard,
probe at one end of the access tube to be logged.
No = average of the past values of Ns taken for prior
8.4.2 Select a timing period for collecting measurement
usage, and
counts based on desired precision (see Annex A3), anticipated
F = value of prescale, a multiplier that alters the count
measurement response, or site-specific logistical criteria.
value for the purpose of display (see A3.1.1.1).
8.4.3 For testing in continuous logging mode, advance the
7.3.6 If the apparatus standardization has not been checked
probe continuously through the access tube while recording
within the previous
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