ASTM D8167/D8167M-23e1

Standard Test Method for In-Place Bulk Density of Soil and Soil-Aggregate by a Low-Activity Nuclear Method (Shallow Depth)

SIGNIFICANCE AND USE
4.1 The test method described is useful as a rapid, nondestructive technique for in-place measurements of bulk density of soil and soil-aggregate. Test results may be used for the determination of dry density if the water content of the soil or soil-aggregate is determined by separate means, such as those methods described in Test Methods D2216, D4643, D4944, and D4959.  
4.2 The test method is used for quality control and acceptance testing of compacted soil and soil-aggregate mixtures as used in construction and also for research and development. The nondestructive nature allows repetitive measurements at a single test location and statistical analysis of the results.  
4.3 Density—The fundamental assumptions inherent in the method is that Compton scattering is the dominant interaction and that the material is homogeneous.
Note 3: The quality of the result produced by this standard test method is dependent on the competence of the personnel performing it, and the suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objective testing/sampling/inspection, and the like. Users of this standard are cautioned that compliance with Practice D3740 does not in itself assure reliable results. Reliable results depend on many factors; Practice D3740 provides a means of evaluating some of those factors.
SCOPE
1.1 This test method describes the procedures for measuring in-place bulk density of soil and soil-aggregate using nuclear equipment with radioactive sources (hereafter referred to simply as “gauges”). These gauges are distinct from those described in Test Method D6938 insofar as:  
1.1.1 These gauges do not contain a system (nuclear or otherwise) for the determination of the water content of the material under measurement.  
1.1.2 These gauges have photon yields sufficiently low as to require the inclusion of background radiation effects on the response during normal operation.
1.1.2.1 For the devices described in Test Method D6938, the contribution of gamma rays detected from the naturally-occurring radioisotopes in most soils (hereafter referred to as “background”) compared to the contribution of gamma rays used by the device to measure in-place bulk density is typically small enough to be negligible in terms of their effect on measurement accuracy. However, for these low-activity gauges, the gamma ray yield from the gauge is low enough that the background contribution from most soils compared to the contribution of gamma rays from the gauge is no longer negligible, and changes in this background can adversely affect the accuracy of the bulk density reading.
1.1.2.2 In order to compensate for potentially differing background contribution to low-activity gauge measurements at different test sites, a background reading must be taken in conjunction with gauge measurements obtained at a given test site. This background reading is utilized in the bulk density calculation performed by the gauge with the goal of minimizing these background effects on the density measurement accuracy.  
1.2 For limitations see Section 5 on Interferences.  
1.3 The bulk density of soil and soil-aggregate is measured by the attenuation of gamma radiation where the source is placed at a known depth up to 300 mm [12 in.] and the detector(s) remains on the surface (some gauges may reverse this orientation).  
1.3.1 The bulk density of the test sample in mass per unit volume is calculated by comparing the detected rate of gamma radiation with previously established calibration data.  
1.3.2 Neither the dry density nor the water content of the test sample is measured by this device. However, the results of this test can be used with the water content or water mass per unit volume value determined by alternative methods to determine the dry density of the test sample.  
1.4 The gauge is calibrated to read the bulk den...

General Information

• Status: Published
• Publication Date: 31-Mar-2023
• ICS: 13.080.01 - Soil quality and pedology in general
• Technical Committee: D18 - Soil and Rock
• Drafting Committee: D18.08 - Special and Construction Control Tests

Relations

• Refers: ASTM D4959-24 - Standard Test Method for Determination of Water Content of Soil By Direct Heating
• Effective Date: 01-Feb-2024
• Refers: ASTM D3740-23 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Nov-2023
• Refers: ASTM D7382-20 - Standard Test Methods for Determination of Maximum Dry Unit Weight of Granular Soils Using a Vibrating Hammer
• Effective Date: 01-Jul-2020
• Refers: ASTM D3740-19 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Oct-2019
• Refers: ASTM D2216-19 - Standard Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass
• Effective Date: 01-Mar-2019
• Refers: ASTM D4944-18 - Standard Test Method for Field Determination of Water (Moisture) Content of Soil by the Calcium Carbide Gas Pressure Tester
• Effective Date: 15-Feb-2018
• Refers: ASTM D2487-17 - Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System)
• Effective Date: 15-Dec-2017
• Refers: ASTM D2487-17e1 - Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System)
• Effective Date: 15-Dec-2017
• Refers: ASTM D2488-17 - Standard Practice for Description and Identification of Soils (Visual-Manual Procedures)
• Effective Date: 15-Jul-2017
• Refers: ASTM D6938-17 - Standard Test Methods for In-Place Density and Water Content of Soil and Soil-Aggregate by Nuclear Methods (Shallow Depth)
• Effective Date: 01-Mar-2017
• Refers: ASTM D4643-17 - Standard Test Method for Determination of Water Content of Soil and Rock by Microwave Oven Heating
• Effective Date: 01-Feb-2017
• Refers: ASTM D4254-16 - Standard Test Methods for Minimum Index Density and Unit Weight of Soils and Calculation of Relative Density
• Effective Date: 01-Mar-2016
• Refers: ASTM D4253-16 - Standard Test Methods for Maximum Index Density and Unit Weight of Soils Using a Vibratory Table
• Effective Date: 01-Mar-2016
• Refers: ASTM D4253-16e1 - Standard Test Methods for Maximum Index Density and Unit Weight of Soils Using a Vibratory Table
• Effective Date: 01-Mar-2016
• Refers: ASTM D4959-16 - Standard Test Method for Determination of Water Content of Soil By Direct Heating
• Effective Date: 01-Jan-2016

Overview

ASTM D8167/D8167M-23e1 is the Standard Test Method for In-Place Bulk Density of Soil and Soil-Aggregate by a Low-Activity Nuclear Method (Shallow Depth). Developed by ASTM International, this standard provides a reliable, rapid, and nondestructive procedure for measuring the in-place bulk density of soil and soil-aggregate using nuclear gauges with low photon yields. Bulk density measurements are vital in construction, research, and quality control applications for compacted soils and soil-aggregate mixtures.

This test method is distinct from other nuclear methods, such as those in ASTM D6938, as it relies on gauges that do not measure water content and have sufficiently low radioactive yields, making background radiation a significant consideration. The method enables repeatable, statistically analyzable measurements, making it ideal for both field and research settings.

Key Topics

• Bulk Density Measurement: Utilizes gamma ray attenuation to determine the in-place bulk density of soils to depths up to 300 mm (12 in).
• Low-Activity Nuclear Gauges: Employs gauges with low radioactive source activity, necessitating background radiation compensation to ensure accuracy.
• Background Radiation Adjustment: Requires site-specific background readings due to low photon yield, minimizing interference and improving measurement precision.
• Calibration Procedures: Gauge calibration must conform to referenced ASTM practices to account for long-term radioactive source decay and environmental factors.
• Quality and Reliability: Emphasizes the importance of operator competence, equipment suitability, and compliance with established practices (e.g., ASTM D3740) for consistent and objective testing.
• Safety Protocols: Outlines proper handling and safety considerations when using nuclear equipment, aligning with regulatory standards for radioactive materials.

Applications

ASTM D8167/D8167M is widely used in sectors such as construction, civil engineering, and geotechnical research. Typical practical applications include:

• Construction Quality Control: Verifying compaction effectiveness of soil and soil-aggregate layers during road building, embankment construction, and other infrastructure projects.
• Field Acceptance Testing: Conducting onsite density tests to ensure compliance with project specifications and regulatory requirements.
• Research and Development: Supporting laboratory and field studies that require nondestructive and repeatable bulk density measurements.
• Performance Monitoring: Tracking changes in soil density for ongoing maintenance of earthwork structures and projects.
• Statistical Analysis: Nondestructive nature enables multiple measurements at a single location, allowing robust statistical evaluation of compaction uniformity.

It is important to note that this method measures only bulk density. To determine dry density, separate water content measurements (using methods described in ASTM D2216, D4643, D4944, or D4959) are required.

Related Standards

ASTM D8167/D8167M references several related standards, enhancing its integration into soil testing programs:

• ASTM D6938: Test Methods for In-Place Density and Water Content of Soil and Soil-Aggregate by Nuclear Methods
• ASTM D2216: Laboratory Determination of Water (Moisture) Content of Soil
• ASTM D4643, D4944, D4959: Various field and laboratory methods for determining water content
• ASTM D3740: Practice for Agencies Engaged in Testing and Inspection of Soil and Rock
• ASTM D6026: Practice for Using Significant Digits in Geotechnical Data
• ASTM D2487, D2488: Practices for Soil Classification and Description

These related standards provide complementary procedures for comprehensive soil analysis, including both density and moisture evaluations, classification, and reporting.

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Keywords: in-place bulk density, soil density, nuclear gauge, low-activity method, construction quality control, ASTM D8167, soil compaction testing, background radiation adjustment, field density, nondestructive testing, soil-aggregate, statistical analysis

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
´1
Designation: D8167/D8167M − 23
Standard Test Method for
In-Place Bulk Density of Soil and Soil-Aggregate by a Low-
Activity Nuclear Method (Shallow Depth)
This standard is issued under the fixed designation D8167/D8167M; 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.
ε NOTE—Minor editorial correction was made in May 2023.
1. Scope* 1.2 For limitations see Section 5 on Interferences.
1.1 This test method describes the procedures for measuring
1.3 The bulk density of soil and soil-aggregate is measured
in-place bulk density of soil and soil-aggregate using nuclear
by the attenuation of gamma radiation where the source is
equipment with radioactive sources (hereafter referred to
placed at a known depth up to 300 mm [12 in.] and the
simply as “gauges”). These gauges are distinct from those
detector(s) remains on the surface (some gauges may reverse
described in Test Method D6938 insofar as:
this orientation).
1.1.1 These gauges do not contain a system (nuclear or
1.3.1 The bulk density of the test sample in mass per unit
otherwise) for the determination of the water content of the
volume is calculated by comparing the detected rate of gamma
material under measurement.
radiation with previously established calibration data.
1.1.2 These gauges have photon yields sufficiently low as to
1.3.2 Neither the dry density nor the water content of the
require the inclusion of background radiation effects on the
test sample is measured by this device. However, the results of
response during normal operation.
this test can be used with the water content or water mass per
1.1.2.1 For the devices described in Test Method D6938, the
unit volume value determined by alternative methods to
contribution of gamma rays detected from the naturally-
determine the dry density of the test sample.
occurring radioisotopes in most soils (hereafter referred to as
1.4 The gauge is calibrated to read the bulk density of soil
“background”) compared to the contribution of gamma rays
or soil-aggregate.
used by the device to measure in-place bulk density is typically
small enough to be negligible in terms of their effect on
1.5 All observed and calculated values shall conform to the
measurement accuracy. However, for these low-activity
guidelines for significant digits and rounding established in
gauges, the gamma ray yield from the gauge is low enough that
Practice D6026.
the background contribution from most soils compared to the
1.5.1 For purposes of comparing, a measured or calculated
contribution of gamma rays from the gauge is no longer
value(s) with specified limits, the measured or calculated
negligible, and changes in this background can adversely affect
value(s) shall be rounded to the nearest decimal or significant
the accuracy of the bulk density reading.
digits in the specified limits.
1.1.2.2 In order to compensate for potentially differing
1.5.2 The procedures used to specify how data are collected/
background contribution to low-activity gauge measurements
recorded and calculated in this standard are regarded as the
at different test sites, a background reading must be taken in
industry standard. In addition, they are representative of the
conjunction with gauge measurements obtained at a given test
significant digits that should generally be retained. The proce-
site. This background reading is utilized in the bulk density
dures used do not consider material variation, purpose for
calculation performed by the gauge with the goal of minimiz-
obtaining the data, special purpose studies, or any consider-
ing these background effects on the density measurement
ations for the user’s objectives; and it is common practice to
accuracy.
increase or reduce significant digits of reported data to com-
mensurate with these considerations. It is beyond the scope of
this standard to consider significant digits used in analysis
This test method is under the jurisdiction of ASTM Committee D18 on Soil and
methods for engineering design.
Rock and is the direct responsibility of Subcommittee D18.08 on Special and
Construction Control Tests.
1.6 Units—The values stated in either SI units or inch-
Current edition approved April 1, 2023. Published April 2023. Originally
pound units are to be regarded separately as standard. The
approved in 2018. Last previous edition approved in 2018 as D8167/D8167M–18a.
DOI: 10.1520/D8167_D8167M–23E01. values stated in each system may not be exact equivalents;
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
´1
D8167/D8167M − 23
therefore, each system shall be used independently of the other. ture) Content of Soil by the Calcium Carbide Gas Pressure
Combining values from the two systems may result in non- Tester
conformance with the standard. Reporting test results in units D4959 Test Method for Determination of Water Content of
other than SI shall not be regarded as nonconformance with Soil By Direct Heating
this standard. D6026 Practice for Using Significant Digits and Data Re-
cords in Geotechnical Data
1.7 This standard does not purport to address all of the
D6938 Test Methods for In-Place Density and Water Content
safety concerns, if any, associated with its use. It is the
of Soil and Soil-Aggregate by Nuclear Methods (Shallow
responsibility of the user of this standard to establish appro-
Depth)
priate safety, health, and environmental practices and deter-
D7013/D7013M Guide for Calibration Facility Setup for
mine the applicability of regulatory limitations prior to use.
Nuclear Surface Gauges
NOTE 1—Nuclear density gauge manuals and reference materials, as
D7382 Test Methods for Determination of Maximum Dry
well as the gauge displays themselves, typically refer to bulk density as
Unit Weight of Granular Soils Using a Vibrating Hammer
“wet density” or “WD.”
D7759/D7759M Guide for Nuclear Surface Moisture and
NOTE 2—The term “bulk density” is used throughout this standard. This
term has different definitions in Terminology D653, depending on the Density Gauge Calibration
context of its use. For this standard, however, “bulk density” refers to, as
E177 Practice for Use of the Terms Precision and Bias in
defined in Terminology D653, “the total mass of partially saturated or
ASTM Test Methods
saturated soil or rock per unit total volume.”
E691 Practice for Conducting an Interlaboratory Study to
1.8 This international standard was developed in accor-
Determine the Precision of a Test Method
dance with internationally recognized principles on standard-
3. Terminology
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
3.1 Definitions:
mendations issued by the World Trade Organization Technical
3.1.1 For definitions of common technical terms used in this
Barriers to Trade (TBT) Committee.
standard, refer to Terminology D653.
3.2 Definitions of Terms Specific to This Standard:
2. Referenced Documents
3.2.1 nuclear gauge, n—a device containing one or more
2.1 ASTM Standards:
radioactive sources used to measure certain properties of soil
D653 Terminology Relating to Soil, Rock, and Contained
and soil-aggregates.
Fluids
3.2.2 probe, n—aslender, elongated device, part of the
D698 Test Methods for Laboratory Compaction Character-
gauge, that is inserted into the soil being measured by the
istics of Soil Using Standard Effort (12,400 ft-lbf/ft (600
gauge. This device may contain either a radioactive source, a
kN-m/m ))
radiation detection device, or both. Probes containing only a
D1557 Test Methods for Laboratory Compaction Character-
radioactive source are commonly referred to as “source rods.”
istics of Soil Using Modified Effort (56,000 ft-lbf/ft
3 3.2.3 test count, n—the measured output of a detector for a
(2,700 kN-m/m ))
specific type of radiation for a given test.
D2216 Test Methods for Laboratory Determination of Water
3.2.4 standardization count, n—the measured output of a
(Moisture) Content of Soil and Rock by Mass
D2487 Practice for Classification of Soils for Engineering detector taken for the purposes of evaluating gauge stability
and accounting for long-term aging of the radioactive sources.
Purposes (Unified Soil Classification System)
D2488 Practice for Description and Identification of Soils This output is frequently referred to as the “standard count” as
well.
(Visual-Manual Procedures)
D3740 Practice for Minimum Requirements for Agencies
3.2.5 background count, n—the counts measured by the
Engaged in Testing and/or Inspection of Soil and Rock as
gauge to evaluate the ambient radiation in the proximity where
Used in Engineering Design and Construction
a test measurement is to be taken rather than the radiation
D4253 Test Methods for Maximum Index Density and Unit
emitted by the gauge itself.
Weight of Soils Using a Vibratory Table
3.2.6 background position, n—the orientation of the gauge
D4254 Test Methods for Minimum Index Density and Unit
source rod when the background count is acquired.
Weight of Soils and Calculation of Relative Density
D4643 Test Method for Determination of Water Content of
4. Significance and Use
Soil and Rock by Microwave Oven Heating
4.1 The test method described is useful as a rapid, nonde-
D4718/D4718M Practice for Correction of Unit Weight and
structive technique for in-place measurements of bulk density
Water Content for Soils Containing Oversize Particles
of soil and soil-aggregate. Test results may be used for the
D4944 Test Method for Field Determination of Water (Mois-
determination of dry density if the water content of the soil or
soil-aggregate is determined by separate means, such as those
methods described in Test Methods D2216, D4643, D4944,
For referenced ASTM standards, visit the ASTM website, www.astm.org, or and D4959.
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
4.2 The test method is used for quality control and accep-
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. tance testing of compacted soil and soil-aggregate mixtures as
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D8167/D8167M − 23
used in construction and also for research and development. 5.1.8.1 For scintillation detectors, changing temperatures
The nondestructive nature allows repetitive measurements at a may cause variations in the resulting light output distribution
single test location and statistical analysis of the results. from the crystal—both in magnitude and shape of the spec-
trum. These variations may result in corresponding variations
4.3 Density—The fundamental assumptions inherent in the
in the number of counted photons and, consequently, the wet
method is that Compton scattering is the dominant interaction
density determined from the measurement.
and that the material is homogeneous.
5.1.8.2 The changes to the detector response due to tem-
NOTE 3—The quality of the result produced by this standard test method
perature changes are compensated by various detector stabili-
is dependent on the competence of the personnel performing it, and the
zation methods that compare current detector response to a
suitability of the equipment and facilities used. Agencies that meet the
standardized response and correct for energy spectrum changes
criteria of Practice D3740 are generally considered capable of competent
accordingly.
and objective testing/sampling/inspection, and the like. Users of this
5.1.8.3 The working temperature range of the gauge at
standard are cautioned that compliance with Practice D3740 does not in
itself assure reliable results. Reliable results depend on many factors;
which the aforementioned temperature variations are compen-
Practice D3740 provides a means of evaluating some of those factors.
sated is provided in the gauge specifications. In general, for a
gauge using a sodium iodide scintillation detector, the working
5. Interferences
temperature range is similar to that of a nuclear gauge using
Geiger-Mueller gas detectors: –10 to 70 °C [14 to 158 °F].
5.1 In-Place Density Interferences:
Please refer to the operator’s manual to find the operating
5.1.1 Measurements may be affected by the chemical com-
temperature range of the gauge.
position of the material being tested.
5.1.8.4 For special applications where the gauge is used
5.1.2 Measurements may be affected by non-homogeneous
outside the operating temperature range, please consult the
soils and surface texture (see 10.2). Excessive voids in the
gauge manufacturer.
prepared test surface beneath the gauge can cause density
measurements that are lower than the actual soil density.
NOTE 4—Separation of the gauge described in this standard by a
distance of 9 m [30 ft] from one another, or from the gauges described in
Excessive use of fill material to compensate for these voids
Test Method D6938, has typically proven sufficient in preventing radiation
may likewise cause biased density measurements.
from one gauge from being detected by another gauge and potentially
5.1.3 The measurement volume of the gauge in a given
causing an incorrect standardization or test measurement reading. This
probe orientation extends from near the tip of the probe (which
separation can be reduced by the proper use of shielding. With regards to
can be placed at a known depth up to 300 mm [12 in.]) to the reflections from large masses or other items potentially causing incorrect
standardization counts, a separation of 1 m [3 ft] between the gauge and
detector at the surface of the in situ material under measure-
the mass or item in question has typically proven sufficient to prevent such
ment. This volume is similar to that described by the volume
reflections from influencing the standardization counts.
bounded by an elliptic paraboloid surface. This volume varies
for different depths of the probe within the material under
6. Apparatus
measurement. Large particles near the probe tip may also
6.1 Nuclear Density Gauge—While exact details of con-
distort the volume of measurement of the gauge.
struction of the apparatus may vary, the system shall consist of:
5.1.4 Gravel particles or large voids in the source-detector
6.1.1 Gamma Source—A sealed source of high-energy
path may cause higher or lower density measurements. Where
gamma radiation such as cesium, cobalt, or radium.
lack of uniformity in the soil due to layering, aggregate or
6.1.2 Gamma Detector—Any type of gamma detector, but
voids is suspected, the test site should be excavated and
typically a scintillation detector or semiconductor based detec-
visually examined to determine whether the test material is
tor.
representative of the in situ material in general and whether an
6.2 Site Preparation Device—A plate, straightedge, or other
oversize correction is required in accordance with Practice
D4718/D4718M. suitable leveling tool that may be used for planing the test site
to the required smoothness and guiding the drive pin to prepare
5.1.5 The measured volume is approximately 0.0057 m
a perpendicular hole.
[0.20 ft ] when the test depth is 150 mm [6 in.]. The actual
measured volume is indeterminate and varies with the appara-
6.3 Drive Pin—A pin of slightly larger diameter than the
tus and the density of the material.
probe in the instrument, used to prepare a hole in the test site
5.1.6 Perform gauge measurements with the gauge far
for inserting the probe.
enough away from other apparatus containing radioactive
6.3.1 Drive Pin Guide—A fixture that keeps the drive pin
sources to prevent interference due to radiation from the other
perpendicular to the test site. Generally part of the site
apparatus. (See Note 4.)
preparation device.
5.1.7 For gauges with low source activity, variations in
6.4 Hammer—Heavy enough to drive the pin to the required
ambient background radiation from one test site to another may
depth without undue distortion of the hole.
significantly influence test results. In such instances this
6.5 Drive Pin Extractor—A tool that may be used to remove
ambient background radiation must be measured at the test site
the drive pin in a vertical direction so that the pin will not
in conjunction with the test measurement and used in the
distort the hole during the extraction process.
calculation of the measured bulk density.
5.1.8 The gamma radiation response for any detector is 6.6 Slide Hammer, with a Drive Pin Attached—As an
typically influenced by the environmental testing temperature. alternative to 6.3 through 6.5, may also be used both to prepare
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D8167/D8167M − 23
a hole in the material to be tested and to extract the pin without 9.2.6 With the gauge placed over the prepared hole and the
distortion of the hole. probe in safe position, take a reading that is the duration of a
normal measurement period (where a normal measurement
7. Hazards
period is typically two minutes).
9.2.7 Immediately after the preceding count is complete,
7.1 These gauges utilize radioactive materials that may be
hazardous to the health of the users unless proper precautions lower the probe to background position, into the hole that was
are taken. Users of these gauges must become familiar with formed in 9.2.4, and take a two minute background count. The
applicable safety procedures and government regulations and
difference between the count acquired in 9.2.6 and this back-
follow these standards when using the gauge.
ground constitutes one standardization count.
7.2 Effective user instructions, together with routine safety 9.2.8 Use the procedure recommended by the gauge manu-
procedures, are a mandatory part of the operation and storage facturer to establish the compliance of the standard measure-
of these gauges. ment to the accepted range. Otherwise, without specific rec-
ommendations from the gauge manufacturer, use the procedure
8. Calibration
in 9.2.8.1.
9.2.8.1 If the values of the current standardization count are
8.1 Gauge calibration shall be performed in accordance with
Guides D7759/D7759M and D7013/D7013M. outside the limits set by Eq 1, repeat the standardization check.
If the second standardization check satisfies Eq 1, the gauge is
9. Standardization considered in satisfactory operating condition. If the second
standardization check does not satisfy Eq 1, then the gauge
9.1 Nuclear density gauges are subject to long-term aging of
must be removed from service until such time that the gauge
the radioactive sources, which will change the relationship
can pass this standardization test.
between test count rates and the material bulk density. To
~ ~ !! ~ ~ !!
2 ln 2 t 2 ln 2 t
correct for this aging effect, gauges are calibrated as a ratio of
0.98 N e T # N # 1.02 N e T (1)
~ ! ~ ! ~ ! ~ !
d 1 ⁄ 2 d 1 ⁄ 2
dc d0 dc
the test count rate to a reference count rate.
where:
9.2 Standardization of the gauge must be performed at the
T = the half-life of the isotope that is used for the
d(1/2)
start of each day’s use, and a record of these data must be
density determination in the gauge. For example,
retained for the amount of time required to ensure compliance
for Cs, the radioactive isotope most commonly
with either 9.2.8 or 9.2.8.1, whichever is applicable.
used for density determination in these gauges,
9.2.1 Perform the standardization with the gauge far enough
T , is 11,023 days,
d(1/2)
away from other apparatus containing radioactive sources to
N =
...