ASTM D6031-96
(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
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.
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Designation:D6031–96
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 D 6031; 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 3017 Test Method for Water Content of Soil and Rock in
Place by Nuclear Methods (Shallow Depth)
1.1 This test method covers collection and comparison of
D 4428/D 4428M Test Methods of Crosshole SeismicTest-
logs of thermalized-neutron counts and back-scattered gamma
ing
counts along horizontal or vertical air-filled access tubes.
D 4564 Test Method for Density of Soil in Place by the
1.2 The in situ water content in mass per unit volume and
Sleeve Method
thedensityinmassperunitvolumeofsoilandrockatpositions
D 5195 Test Method for Density of Soil and Rock In-Place
or in intervals along the length of an access tube are calculated
at Depths Below the Surface by Nuclear Methods
by comparing the thermal neutron count rate and gamma count
D 5220 Test Method for Water Content of Soil and Rock
rates respectively to previously established calibration data.
In-Place by the Neutron Depth Probe Method
1.3 The values stated in SI units are regarded as the
standard. The inch-pound units given in parentheses may be
3. Significance and Use
approximate and are provided for information only.
3.1 This test method is useful as a repeatable, nondestruc-
1.4 This standard does not purport to address all of the
tive technique to monitor in-place density and moisture of soil
safety concerns, if any, associated with its use. It is the
and rock along lengthy sections of horizontal, slanted, and
responsibility of the user of this standard to establish appro-
vertical access holes or tubes. With proper calibration in
priate safety and health practices and determine the applica-
accordance with Annex A1, this test method can be used to
bility of regulatory limitations prior to use. For specific
quantify changes in density and moisture content of soil and
hazards, see Section 6.
rock.
2. Referenced Documents 3.2 This test method is used in vadose zone monitoring, for
performance assessment of engineered barriers at waste facili-
2.1 ASTM Standards:
ties, and for research related to monitoring the movement of
D 1452 Practice for Soil Investigation and Sampling by
liquids (water solutions and hydrocarbons) through soil and
Auger Borings
rock. The nondestructive nature of the test allows repetitive
D 1586 Test Method for Penetration Test and Split/Barrel
measurements at a site and statistical analysis of results.
Sampling of Soils
2 3.3 The fundamental assumptions inherent in this test
D 1587 Practice for Thin-Walled Tube Sampling of Soils
method are that the dry bulk density of the test material is
D 2113 Practice for Diamond Core Drilling for Site Inves-
2 constant and that the response to fast neutrons and gammaray
tigation
energy associated with soil and liquid chemistry is constant.
D 2216 TestMethodforLaboratoryDeterminationofWater
(Moisture) Content of Soil and Rock
4. Interferences
D 2922 Test Methods for Density of Soil and Soil-
4.1 The sample heterogeneity and chemical composition of
Aggregate in Place by Nuclear Methods (Shallow Depth)
the material under test will affect the measurement of both
D 2937 Test Method for Density of Soil in Place by the
moisture and density.The apparatus should be calibrated to the
Drive-Cylinder Method
material under test at a similar density of dry soil or rock and
in the similar type and orientation of access tube, or adjust-
ments must be made in accordance with Annex A2.
This test method is under the jurisdiction of ASTM Committee D-18 on Soil
4.2 Hydrogen, in forms other than water, as defined by Test
and Rock and is the direct responsibility of Subcommittee D18.21 on GroundWater
Method D 2216, will cause measurements in excess of the true
and Vadose Zone Investigations.
moisture content. Some elements such as boron, chlorine, and
Current edition approved Oct. 10, 1996. Published February 1997.
Annual Book of ASTM Standards, Vol 04.08. minute quantities of cadmium, if present in the material under
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D6031–96
test, will cause measurements lower than the true moisture plastic, having an interior diameter large enough to permit
content. Some elements with atomic numbers greater than 20 probeaccesswithoutbinding,andanexteriordiameterassmall
such as iron or other heavy metals may cause measurements as possible to provide close proximity of the material under
higher than the true density value. test. The same type of tubing must be used in the field as is
4.3 The measurement of moisture and density using this test
used in calibration.
method exhibits spatial bias in that it is more sensitive to the
5.2.2 Hand Auger or Power Drilling/Trenching
material closest to the access tube. The density and moisture
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
lation of access tubing and insertion of the probe that ensures
3 3
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-
Equipment that can be used to move the probe through the
3 3
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
taken. Users of this equipment must become completely familiar with all
the indicated moisture content to be greater than the true
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
5. Apparatus together with routine safety procedures are a recommended part of the
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,
vary, the system shall consist of:
the user should take additional care to learn its proper use in conjunction
5.1.1 Fast Neutron Source—A sealed mixture of a radioac-
with measurement apparatus. Known safety hazards such as cutting and
tive material such as americium or radium and a target material
pinching exist when using such equipment.
such as beryllium, or other fast neutron sources such as
NOTE 3—Thistestmethoddoesnotcoverallsafetyprecautions.Itisthe
californium that do not require a target.
responsibility of the users to familiarize themselves with all safety
5.1.2 Slow Neutron Detector—Any type of slow neutron precautions.
detector, such as boron trifluoride or helium-3 proportional
7. Calibration, Standardization, and Reference Check
counters.
5.1.3 High-Energy Gamma-Radiation Source— A sealed
7.1 Calibrate the instrument in accordance with Annex A1.
source of radioactive material, such as cesium-137, cobalt-60,
7.2 Adjust the calibration in accordance with Annex A2 if
or radium-226.
adjustments are necessary.
5.1.4 Gamma Detector—Any type of gamma detector, such
7.3 Standardization and Reference Check:
as a Geiger-Mueller tube.
7.3.1 Nuclear apparatus are subject to the long-term decay
5.1.5 Suitable Readout Device:
of the radioactive source and aging of detectors and electronic
5.1.6 Cylindrical Probe—The apparatus shall be equipped
systems that may change the relationship between count rate
with a cylindrical probe, containing the neutron and gamma
and either the material density or the moisture content of the
sources and the detectors, connected by a cable or cables of
material, or both. To correct for these changes, the apparatus
sufficient design and length, that are capable of raising and
may be calibrated periodically. To minimize error, moisture
lowering the probe in vertical applications and pulling it in
and density measurements commonly are reported as count
horizontal applications, to the desired measurement location.
ratios, the ratio of the measured count rate to a count rate made
5.1.7 Reference Standard—A device containing dense, hy-
in a reference standard. The reference count rate should be
drogenous material for checking equipment operation and to
similar or higher than the count rates over the useful measure-
establish conditions for a reproducible reference count rate. It
ment range of the apparatus.
also may serve as a radiation shield.
5.2 Accessories shall include: 7.3.2 Standardization of equipment on the reference stan-
5.2.1 AccessTubing—Theaccesstubing(casing)isrequired dard is required at the start of each day’s use and a permanent
for all access holes in nonlithified materials (soils and poorly record of these data shall be retained.The standardization shall
consolidated rock) that cannot maintain constant borehole be performed with the equipment located at least 10 m (33 ft)
diameter with repeated measurements. If access tubing is away from other radioactive sources and large masses or other
required it must be of a material, such as aluminum, steel, or items that may affect the reference count rate.
D6031–96
7.3.3 If recommended by the apparatus manufacturer to density measurements in all soil types. Grouting should not be
provide more stable and consistent results, turn on the appara- used unless it is required to seal off flow pathways along the
tus prior to use to allow it to stabilize and leave the power on access tube, such as in some vertical borings and where
during the day’s testing. trenches cross engineered barriers. Grouting can be accom-
7.3.4 Using the reference standard, take at least four repeti- plished using procedures described in Test Methods D 4428/
tivereadingsatthemanufacturer’srecommendedmeasurement D 4428M.
period of 20 or more at some shorter period and obtain the 8.1.3 Record and note the position of the ground water
mean. If available on the instrument, one measurement at a table, perched water tables, and changes in soil texture as
period of four or more times the normal test measurement drilling or trenching progresses.
period is acceptable. This constitutes one standardization 8.1.4 If ground water is encountered or saturated conditions
check. are expected to develop, seal the tube at seams and open ends
7.3.5 If the value obtained in 7.3.4 is within the following to prevent water seepage into the tube. This will prevent
limits, the equipment is considered to be in satisfactory erroneous measurements and possible damage to the probe.
condition and the value may be used to determine the count 8.1.5 The access tube should project above the ground and
ratios for the day of use. If the value obtained is outside these be capped to prevent foreign material from entering. The
limits, another standardization check should be made. If the access tube should not project out of the test material far
second standardization check is within the limits, the equip- enough to be damaged by equipment traffic.
ment may be used. If it also fails the test, however, the 8.2 Pass a dummy probe through the access tube to verify
equipmentshallbeadjustedorrepairedasrecommendedbythe proper clearance before deploying the radioactive sources.
manufacturer. 8.3 Standardize the apparatus (see 7.3).
8.4 Proceed with the test run in a continuous logging mode
No No
No 1 2F . Ns . No 2 2F or in a noncontinuous logging mode as follows:
Œ Œ
F F
8.4.1 Set up the winching equipment or other motive
where: devices (see 5.2.3) to begin a logging run by stationing the
Ns = value of current standardization check (7.3.4) on the
probe at one end of the access tube to be logged.
reference standard,
8.4.2 Select a timing period for collecting measurement
No = average of the past values of Ns taken for prior
counts based on desired precision (see Annex A3), anticipated
usage, and
measurement response, or site-specific logistical criteria.
F = value of prescale, a multiplier that alters the count
8.4.3 For testing in continuous logging mode, advance the
value for the purpose of display (see A3.1.1.1).
probe continuously through the access tube while recording
7.3.6 If the apparatus standardization has not been checked
data that relate gamma counts and thermal neutron counts to
within the previous three months, perform at lest four new
position intervals or time (for constant logging speed), or both.
standardization checks and use the mean as the value for No.
8.4.4 For testing in noncontinuous logging mode, advance
7.3.7 The value of Ns will be used to determine the count
the probe through the access tube to the desired position and
ratios for the current day’s use of the equipment. If, for any
stop,recordcountswhileprobeisstationary,advancetheprobe
reason, either the measured density or moisture content be-
to the next desired position, and repeat. Record data relating
come suspect during the day’s use, perform another standard-
gamma counts and thermal neutron counts to discrete positions
ization to ensure that the equipment is stable.
along the access tube.
8. Procedure
9. Calculation
8.1 Installation of Access Tu
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