ASTM D4125/D4125M-21

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Designation: D4125/D4125M − 10 (Reapproved 2016) D4125/D4125M − 21
Standard Test Methods for
Asphalt Content of BituminousAsphalt Mixtures by the
Nuclear Method
This standard is issued under the fixed designation D4125/D4125M; 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
1.1 These test methods cover the procedures for determining the asphalt content of samples of uncompacted bituminousasphalt
mixtures (Test Method A), and of laboratory compacted specimens of bituminousasphalt mixtures (Test Method B) by examining
a test sample with an apparatus that utilizes neutron thermalization techniques.
1.2 The values stated in either SI units or inch-pound units 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-conformancenonconformance with the standard.
1.3 A precision and bias statement for Method B in this standard has not been developed at this time. Therefore, Method B should
not be used for acceptance or rejection of a material for purchasing purposes.
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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use. See Section 6 and 8.4.2, 8.5.6, and Note 4, for specific hazards.
1.5 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.
2. Referenced Documents
2.1 ASTM Standards:
C670 Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials
D75D75/D75M Practice for Sampling Aggregates
D140D140/D140M Practice for Sampling Asphalt Materials
D979D979/D979M Practice for Sampling Bituminous Paving Mixtures
D1461 Test Method for Moisture or Volatile Distillates in Asphalt Mixtures
D1559 Test Method for Resistance to Plastic Flow of Bituminous Mixtures Using Marshall Apparatus (Withdrawn 1998)
D1561D1561/D1561M Practice for Preparation of Bituminous Mixture Test Specimens by Means of California Kneading
Compactor
These test methods are under the jurisdiction of ASTM Committee D04 on Road and Paving Materials and isare the direct responsibility of Subcommittee D04.25 on
Analysis of Asphalt Mixtures.
Current edition approved Oct. 1, 2016April 1, 2021. Published October 2016April 2021. Originally approved in 1983. Last previous edition approved in 20102016 as
D4125/D4125M – 10.D4125/D4125M – 10 (2016). DOI: 10.1520/D4125_D4125M-10R16.10.1520/D4125_D4125M-21.
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 ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4125/D4125M − 21
D3387 Test Method for Compaction and Shear Properties of Bituminous Mixtures by Means of the U.S. Corps of Engineers
Gyratory Testing Machine (GTM) (Withdrawn 2020)
D4013 Practice for Preparation of Test Specimens of Bituminous Mixtures by Means of Gyratory Shear Compactor (Withdrawn
2013)
3. Significance and Use
3.1 These test methods are useful as a rapid, nondestructive technique for determination of asphalt content of bituminousasphalt
mixtures.
3.2 These test methods are suitable for quality control and acceptance testing for construction and for research and development
applications. The test method is used for determination of asphalt content only as it does not provide extracted aggregate for
gradation analysis.
3.3 The non-destructivenondestructive nature of the test allows repetitive measurements to be made on a single test sample for
statistical analysis of test data.
3.4 These test methods determine the asphalt content of a test sample by comparing the measured asphalt content with previously
established calibration data.
3.4.1 The asphalt content of a material expressed as a percentage,percentage is the ratio of the mass of asphalt in a given mass
of material to the total mass of the sample or to the mass of the solid material particles.
4. Interferences
4.1 The fundamental assumptions inherent in this test method are that the material under test is homogeneous and that hydrogen
present is in the form of asphalt or has been otherwise accounted for in the calibration process.
4.2 Accurate results will be dependent upon proper calibration of the apparatus to the material being tested.
4.3 This apparatus measures the total amount of hydrogen in the sample, including hydrogen present in the form of water. Unless
the test sample is free of water, such percentage must be determined in accordance with the provisions of Test Method D1461 and
the percentage determined subtracted from the asphalt percentage as measured by the apparatus.
4.3.1 Alternatively, the sample may be dried to a constant mass in an oven at 110 6 5°C5 °C [230 6 9°F],9 °F], thereby nullifying
the need for the correction.
4.4 This apparatus may be sensitive to outside influences,influences; therefore, any other source of neutron radiation shall be kept
at least 10 m [30 ft] from the apparatus during use. The area around the apparatus shall be kept free of large amounts of
hydrogenous material,material such as water, plastics, or asphalt during use.
4.5 Moving the apparatus to a different location, even within the same laboratory, can cause a change in background radiation
measurements. Also, if objects containing hydrogenous materials are moved in the area near the apparatus, the measurement counts
may be affected. New background measurements shall be taken prior to use whenever background conditions have changed (see
Section 10).
5. Apparatus
5.1 While exact details of construction for the apparatus may vary, the system shall consist of the following items:
5.1.1 Neutron Source—An encapsulated and sealed radioactive source such as americium/beryllium.
5.1.2 Detectors—Any type of thermal neutron detectors, such as helium-3 or boron trifluoride.
5.1.3 Read-Out Instrument, such as a scaler or a direct reading digital device calibrated in percent asphalt.
D4125/D4125M − 21
FIG. 1 Molded Laboratory Specimen-Containers Specimen Containers Measurement Values in SI Units (CM)—Other Values for Refer-
ence Only
5.2 Other Apparatus:
5.2.1 Stainless Steel Sample Pans, of uniform size and mass.
5.2.2 Balance, capable of weighing to 20 kg [44 lb], readable to 1 g [0.0002 lbm].
5.2.3 Oven, capable of heating to 177 6 3°C3 °C [350 6 5°F].5 °F].
5.2.4 Straightedge, steel, approximately 450 mm [18 in.] in length.
5.2.5 Flat Plate, metal or wood, having an area slightly larger than the sample pan. The metal plate shall have a minimum
3 3
thickness of 10 mm [ ⁄8 in.]. The wooden plate shall have a minimum thickness of 20 mm [ ⁄4 in.].
5.2.6 Assorted Spoons and Mixing Bowls.
5.2.7 Thermometer with a temperature range of 10 to 250°C250 °C [50 to 482°F].482 °F].
5.3 Additional Apparatus for Test Method B:
5.3.1 Molded Laboratory Specimen Container, (provided by instrument manufacturer) to allow for proper testing of laboratory
compacted samples (see Fig. 1).
5.3.2 Apparatus, necessary to prepare compacted specimens as specified in Test Methods D1559, D1561,and D3387, or
PracticePractices D1561/D1561M and D4013.
6. Hazards
6.1 Warning—This equipment utilizes radioactive materials which may be hazardous to the health of the users unless proper
precautions are taken. Users of this equipment must become completely familiar with possible safety hazards and with all
applicable regulations concerning the handling and use of radioactive materials. Effective user instructions together with routine
D4125/D4125M − 21
safety procedures are a recommended part of the operation of this apparatus.Warning—This equipment utilizes radioactive
materials which may be hazardous to the health of the users unless proper precautions are taken. Users of this equipment must
become completely familiar with possible safety hazards and with all applicable regulations concerning the handling and use of
radioactive materials. Effective user instructions together with routine safety procedures are a recommended part of the operation
of this apparatus.
7. Sampling
7.1 Obtain random samples of aggregates in accordance with Practice D75D75/D75M.
7.2 Obtain random samples of freshly produced bituminousasphalt paving mixture in accordance with Practice D979D979/
D979M.
7.3 Obtain random samples of bituminousasphalt materials in accordance with Practice D140D140/D140M.
8. Calibration
8.1 The test results obtained using this test method will be influenced by the types of aggregate, source, and grade of asphalt, and
by the mix gradation. Accordingly, a calibration curve must be developed for each mix type and aggregate blend to be tested under
this test method.
8.1.1 A new calibration curve shall be developed whenever there is a change in the source of asphalt or aggregate or a significant
change in aggregate gradation.
8.1.2 A new calibration curve shall be established for new or repaired apparatus.
8.2 For Test Method A, calibrate the apparatus using the following procedures:
8.2.1 Sample the aggregates in accordance with 7.1 and blend the aggregates in the proper proportions. Obtain enough aggregate
for a minimum of three samples. Approximately 30 kg 30 kg [65 lb] will be required, and
8.2.2 Sample the bituminousasphalt materials in accordance with 7.3. Approximately 2.5 kg [5.5 lb] will be required.
8.3 Use a minimum of three prepared samples to establish the calibration curve. The range of asphalt contents shall vary by at
least two percent 2 % asphalt content from the lowest to the highest contents in the samples. The range shall encompass the asphalt
content of the proposed mix design. The mass of the samples shall be within 10 g [0.02 lb] of each other.
8.3.1 Unless the apparatus makes provision for temperature corrections, all calibration samples shall be tested at a uniform
temperature,temperature within 65°C [9°F].65 °C [9 °F]. Calibration samples should be prepared and tested as closeclosely as
possible to the temperature of test samples of completed mixes.
8.4 Prepare a blank sample (sample of hot, dry aggregate without asphalt) to determine the mass to be used for calibration and
plant mix samples. Using this mass will ensure the same average density for all test samples.
8.4.1 Thoroughly mix at least 10 kg [22 lb] of the aggregate after heating and drying it to a constant mass and temperature.
8.4.2 Fill a sample pan with the aggregate in two or three layers, avoiding segregation. Using a scoop or spatula, distribute the
aggregate to reduce voids and segregation. For each layer raise the pan approximately 20 to 50 mm [1 to 2 in.] from the working
surface and tap the pan against the working surface two or three times to settle the contents. Fill the pan to a point slightly above
the top edge. Slide a straightedge along the top of the pan until the aggregate is absolutely flush with the top edge of the pan.
(Caution—Do not compact the sample.)
8.4.3 Determine the mass of the blank sample to the nearest gram and record data. Use this mass for all calibration and plant mix
test samples. (See Note 2.)
8.4.4 Place the pan containing the blank sample in the apparatus and take a measurement in accordance with the manufacturer’s
instructions.
D4125/D4125M − 21
8.4.5 Record the blank sample count.
8.4.6 To detect changes in aggregate that may affect test results, a sample of aggregate may be prepared and tested each day as
described herein. If a significant change in the count [60.5 %](60.5 %) has occurred, then check the calibration as described in
9.3. If necessary, prepare a new calibration curve as outlined in 8.5 (see Note 1).
NOTE 1—Batch plant hot bin samples may be used to obtain the dry aggregate count. Care must be taken to ensure that the aggregate is completely dried
and properly mixed before testing when using hot bin samples.
8.5 Prepare a minimum of three calibration samples using the following procedures:
8.5.1 Heat the aggregates and asphalt cement to approximately 150°C [300°F].150 °C [300 °F]. Heat all bowls, sample pans, and
tools to approximately 150°C [300°F].150 °C [300 °F].
8.5.2 To prevent samples from being biased by residual asphalt retained in the mixing bowl, do not clean the bowl after each
mixing of the samples. Scrape it clean, leaving a coat
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