ASTM D6031/D6031M-96(2010)e1
(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 either inch-pound units or SI units [presented in brackets] are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.
1.3.1 The gravitational system of inch-pound units is used when dealing with inch-pound units. In this system, the pound (lbf) represents a unit of force (weight), while the unit for mass is slugs. The rationalized slug unit is not given, unless dynamic (F = ma) calculations are involved.
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)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
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Designation: D6031/D6031M − 96(Reapproved 2010)
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/D6031M; 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.
´ NOTE—The units statement in 1.3 and the designation were revised editorially in August 2010.
1. Scope D1452 Practice for Soil Exploration and Sampling byAuger
Borings
1.1 This test method covers collection and comparison of
D1586 Test Method for Penetration Test (SPT) and Split-
logs of thermalized-neutron counts and back-scattered gamma
Barrel Sampling of Soils
counts along horizontal or vertical air-filled access tubes.
D1587 Practice for Thin-Walled Tube Sampling of Soils for
1.2 The in situ water content in mass per unit volume and
Geotechnical Purposes
thedensityinmassperunitvolumeofsoilandrockatpositions
D2113 Practice for Rock Core Drilling and Sampling of
or in intervals along the length of an access tube are calculated
Rock for Site Investigation
by comparing the thermal neutron count rate and gamma count
D2216 Test Methods for Laboratory Determination of Water
rates respectively to previously established calibration data.
(Moisture) Content of Soil and Rock by Mass
1.3 The values stated in either inch-pound units or SI units D2922 Test Methods for Density of Soil and Soil-Aggregate
in Place by Nuclear Methods (Shallow Depth) (With-
[presented in brackets] are to be regarded separately as
standard. The values stated in each system may not be exact drawn 2007)
D2937 Test Method for Density of Soil in Place by the
equivalents;therefore,eachsystemshallbeusedindependently
of the other. Combining values from the two systems may Drive-Cylinder Method
D3017 Test Method for Water Content of Soil and Rock in
result in non-conformance with the standard.
1.3.1 The gravitational system of inch-pound units is used Place by Nuclear Methods (Shallow Depth)
D3550 Practice for Thick Wall, Ring-Lined, Split Barrel,
when dealing with inch-pound units. In this system, the pound
Drive Sampling of Soils
(lbf) represents a unit of force (weight), while the unit for mass
is slugs.The rationalized slug unit is not given, unless dynamic D4428/D4428M Test Methods for Crosshole Seismic Test-
ing
(F = ma) calculations are involved.
D4564 Test Method for Density and Unit Weight of Soil in
1.4 This standard does not purport to address all of the
Place by the Sleeve Method
safety concerns, if any, associated with its use. It is the
D5195 Test Method for Density of Soil and Rock In-Place at
responsibility of the user of this standard to establish appro-
Depths Below Surface by Nuclear Methods
priate safety and health practices and determine the applica-
D5220 Test Method for Water Mass per Unit Volume of Soil
bility of regulatory limitations prior to use. For specific
and Rock In-Place by the Neutron Depth Probe Method
hazards, see Section 6.
3. Significance and Use
2. Referenced Documents
3.1 This test method is useful as a repeatable, nondestruc-
2.1 ASTM Standards:
tive technique to monitor in-place density and moisture of soil
and rock along lengthy sections of horizontal, slanted, and
Thistestmethodisunder the jurisdiction ofASTM CommitteeD18onSoiland
vertical access holes or tubes. With proper calibration in
Rock and is the direct responsibility of Subcommittee D18.21 on Groundwater and
accordance with Annex A1, this test method can be used to
Vadose Zone Investigations.
Current edition approved Aug. 1, 2010. Published September 2010. Originally
quantify changes in density and moisture content of soil and
approved in 1996. Last previous edition approved in 2004 as D6031–96(2004).
rock.
DOI: 10.1520/D6031_D6031M-96R10E01.
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 The last approved version of this historical standard is referenced on
the ASTM website. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D6031/D6031M − 96 (2010)
3.2 This test method is used in vadose zone monitoring, for 5.1.2 Slow Neutron Detector—Any type of slow neutron
performance assessment of engineered barriers at waste facili- detector, such as boron trifluoride or helium-3 proportional
ties, and for research related to monitoring the movement of counters.
liquids (water solutions and hydrocarbons) through soil and
5.1.3 High-Energy Gamma-Radiation Source— A sealed
rock. The nondestructive nature of the test allows repetitive
source of radioactive material, such as cesium-137, cobalt-60,
measurements at a site and statistical analysis of results.
or radium-226.
3.3 The fundamental assumptions inherent in this test 5.1.4 Gamma Detector—Any type of gamma detector, such
as a Geiger-Mueller tube.
method are that the dry bulk density of the test material is
constant and that the response to fast neutrons and gammaray
5.1.5 Suitable Readout Device:
energy associated with soil and liquid chemistry is constant.
5.1.6 Cylindrical Probe—The apparatus shall be equipped
with a cylindrical probe, containing the neutron and gamma
4. Interferences
sources and the detectors, connected by a cable or cables of
4.1 The sample heterogeneity and chemical composition of
sufficient design and length, that are capable of raising and
the material under test will affect the measurement of both
lowering the probe in vertical applications and pulling it in
moisture and density.The apparatus should be calibrated to the
horizontal applications, to the desired measurement location.
material under test at a similar density of dry soil or rock and
5.1.7 Reference Standard—A device containing dense, hy-
in the similar type and orientation of access tube, or adjust-
drogenous material for checking equipment operation and to
ments must be made in accordance with Annex A2.
establish conditions for a reproducible reference count rate. It
also may serve as a radiation shield.
4.2 Hydrogen, in forms other than water, as defined by Test
Method D2216, will cause measurements in excess of the true
5.2 Accessories shall include:
moisture content. Some elements such as boron, chlorine, and
5.2.1 AccessTubing—The access tubing (casing) is required
minute quantities of cadmium, if present in the material under
for all access holes in nonlithified materials (soils and poorly
test, will cause measurements lower than the true moisture
consolidated rock) that cannot maintain constant borehole
content. Some elements with atomic numbers greater than 20
diameter with repeated measurements. If access tubing is
such as iron or other heavy metals may cause measurements
required it must be of a material, such as aluminum, steel, or
higher than the true density value.
plastic, having an interior diameter large enough to permit
4.3 The measurement of moisture and density using this test
probeaccesswithoutbinding,andanexteriordiameterassmall
method exhibits spatial bias in that it is more sensitive to the
as possible to provide close proximity of the material under
material closest to the access tube. The density and moisture
test. The same type of tubing must be used in the field as is
measurements are necessarily an average of the total sample
used in calibration.
involved.
5.2.2 Hand Auger or Power Drilling/Trenching
4.4 The sample volume for a moisture measurement is
Equipment—Equipmentthatcanbeusedtoestablishtheaccess
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approximately 3.8 ft [0.11 m ] at a moisture content of 12.5 hole or position the access tube when required (see 5.2.1).Any
lbf/ft [200 kg/m ]. The actual sample volume for moisture is equipment that provides a suitable clean open hole for instal-
indeterminate and varies with the apparatus and the moisture lation of access tubing and insertion of the probe that ensures
content of the material. In general the greater the moisture the measurements are performed on undisturbed soil and rock
content of the material, the smaller the measurement volume. while maintaining a constant diameter per width shall be
acceptable. The type of equipment and methods of advancing
4.5 Adensitymeasurementhasasamplevolumeofapproxi-
3 3
the access hole should be reported.
mately 0.8 ft [0.028 m ]. The actual sample volume for
5.2.3 Winching Equipment or Other Motive Devices—
density is indeterminate and varies with the apparatus and the
Equipment that can be used to move the probe through the
densityofthematerial.Ingeneral,thegreaterthedensityofthe
access tubing. The type of such equipment is dependent upon
material, the smaller the measurement volume.
theorientationoftheaccesstubingandthedistanceoverwhich
4.6 Air gaps between the probe and the access tube or voids
the probe must be moved.
around the access tube will cause the indicated moisture
content and density to be less than the calibrated values.
6. Hazards
4.7 Condensed moisture inside the access tube may cause
6.1 Warning—This equipment utilizes radioactive materi-
the indicated moisture content to be greater than the true
als that may be hazardous to the health of the users unless
moisture content of material outside the access tube.
proper precautions are taken. Users of this equipment must
become completely familiar with all possible safety hazards
5. Apparatus
andwithallapplicableregulationsconcerningthehandlingand
5.1 While exact details of construction of the apparatus may
use of radioactive materials. Effective user instructions to-
vary, the system shall consist of:
gether with routine safety procedures are a recommended part
5.1.1 Fast Neutron Source—A sealed mixture of a radioac-
of the operation of this apparatus.
tive material such as americium or radium and a target material
such as beryllium, or other fast neutron sources such as 6.2 Warning—When using winching or other motive
californium that do not require a target. equipment, the user should take additional care to learn its
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D6031/D6031M − 96 (2010)
properuseinconjunctionwithmeasurementapparatus.Known
F = value of prescale, a multiplier that alters the count
safety hazards such as cutting and pinching exist when using
value for the purpose of display (see A3.1.1.1).
such equipment.
7.3.6 If the apparatus standardization has not been checked
6.3 This test method does not cover all safety precautions. It
within the previous three months, perform at lest four new
is the responsibility of the users to familiarize themselves with
standardization checks and use the mean as the value for No.
all safety precautions.
7.3.7 The value of Ns will be used to determine the count
ratios for the current day’s use of the equipment. If, for any
7. Calibration, Standardization, and Reference Check
reason, either the measured density or moisture content be-
7.1 Calibrate the instrument in accordance with Annex A1. come suspect during the day’s use, perform another standard-
ization to ensure that the equipment is stable.
7.2 Adjust the calibration in accordance with Annex A2 if
adjustments are necessary.
8. Procedure
7.3 Standardization and Reference Check:
8.1 Installation of Access Tubing (Casing):
7.3.1 Nuclear apparatus are subject to the long-term decay
8.1.1 Drilltheaccessholeorexcavateatrenchatthedesired
of the radioactive source and aging of detectors and electronic
location and install the access tube in a manner to maximize
systems that may change the relationship between count rate
contactwithtestmaterialandminimizevoids.Theaccesstubes
and either the material density or the moisture content of the
should fit snugly into the access hole or trench. Unstable
material, or both. To correct for these changes, the apparatus
conditions in fill material around the access tube may result in
may be calibrated periodically. To minimize error, moisture
redistribution of solids over time, piping, or other phenomena
and density measurements commonly are reported as count
that will degrade precision. Voids caused during drilling, tube
ratios, the ratio of the measured count rate to a count rate made
installation,orbackfilling,oracombinationthereof,maycause
in a reference standard. The reference count rate should be
erroneously low results. Excessive compaction of clay-rich
similar or higher than the count rates over the useful measure-
backfill material will limit the effectiveness of moisture moni-
ment range of the apparatus.
toring for leak detection. Backfill should approximate the
7.3.2 Standardization of equipment on the reference stan-
composition, water content, and bulk density of test material as
dard is required at the start of each day’s use and a permanent
nearly as possible.
record of these data shall be retained.The standardization shall
8.1.2 Grouting of annular spaces, if required, should be of
be performed with the equipment located at least 33 ft [10 m]
minimum functional thickness, and grout mixtures should not
away from other radioactive sources and large masses or other
contain excessive water. Grouts thicker than 2 in. [5 cm] 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 groundwater table,
period of four or more times the normal test measurement
period is acceptable. This constitutes one standardization perched water tables, and changes in soil texture as drilling or
check. trenching progresses.
7.3.5 If the value obtained in 7.3.4 is within the following
8.1.4 If groundwater i
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