ASTM D6752/D6752M-23

Standard Test Method for Bulk Specific Gravity and Density of Compacted Asphalt Mixtures Using Automatic Vacuum Sealing Method

SIGNIFICANCE AND USE
4.1 The results obtained from this method can be used to determine the unit weight of compacted asphalt mixtures, and in conjunction with Test Method D3203/D3203M, to obtain percent air voids. These values in turn may be used in determining the relative degree of compaction.  
4.2 Since specific gravity has no units, it must be converted to density in order to do calculations that require units. This conversion is made by multiplying the specific gravity at a given temperature by the density of water at the same temperature.  
4.3 This method can be used for 100 mm [4 in.] and 150 mm [6 in.] diameter cylindrical as well as cubical asphalt mixture specimens to correct for inconsistencies in sample weight determinations resulting from drainage of water from samples and inaccuracy in saturated surface dry weight of absorptive coarse and open-graded mixes. Asphalt mixes such as stone matrix asphalt (SMA), porous friction course, and coarse-graded mixes with significant surface texture and interconnected voids can be tested with this method. Follow manufacturer recommendation for appropriate bag sizes to be utilized with cubical and abnormally shaped samples.4
Note 1: The quality of the results produced by this standard are dependent on the competence of the personnel performing the procedure and the capability, calibration, and maintenance of the equipment used. Agencies that meet the criteria of Specification D3666 are generally considered capable of competent and objective testing, sampling, inspection, etc. Users of this standard are cautioned that compliance with Specification D3666 alone does not completely ensure reliable results. Reliable results depend on many factors; following the suggestions of Specification D3666 or some similar acceptable guideline provides a means of evaluating and controlling some of those factors.
SCOPE
1.1 This test method covers the determination of bulk specific gravity of compacted asphalt mixtures by the vacuum sealing method.  
1.2 This method can be used for compacted cylindrical and cubical laboratory and field asphalt mixture specimens.  
1.3 The bulk specific gravity of the compacted asphalt mixtures may be used in calculating the unit weight of the mixture.  
1.4 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 nonconformance with the standard.  
1.5 The text of this standard references notes and footnotes which provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of the standard.  
1.6 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.7 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.

General Information

• Status: Published
• Publication Date: 31-Oct-2023
• ICS: 75.140 - Waxes, bituminous materials and other petroleum products
• Technical Committee: D04 - Road and Paving Materials
• Drafting Committee: D04.21 - Specific Gravity and Density of Asphalt Mixtures

Relations

• Replaces: ASTM D6752/D6752M-18 - Standard Test Method for Bulk Specific Gravity and Density of Compacted Asphalt Mixtures Using Automatic Vacuum Sealing Method
• Effective Date: 01-Nov-2023
• Refers: ASTM D4753-24 - Standard Guide for Evaluating, Selecting, and Specifying Balances and Standard Masses for Use in Soil, Rock, and Construction Materials Testing
• Effective Date: 01-Feb-2024
• Refers: ASTM C670-24a - Standard Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials
• Effective Date: 01-Feb-2024
• Refers: ASTM C670-24 - Standard Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials
• Effective Date: 01-Jan-2024
• Refers: ASTM C670-15 - Standard Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials
• Effective Date: 15-Jun-2015
• Refers: ASTM D4753-15 - Standard Guide for Evaluating, Selecting, and Specifying Balances and Standard Masses for Use in Soil, Rock, and Construction Materials Testing
• Effective Date: 01-May-2015
• Referred By: ASTM D7870/D7870M-20 - Standard Practice for Moisture Conditioning Compacted Asphalt Mixture Specimens by Using Hydrostatic Pore Pressure
• Effective Date: 01-Nov-2023
• Referred By: ASTM D8303-20 - Standard Test Method for Determining Thermal Cracking Properties of Asphalt Mixtures Through Measurement of Thermally Induced Stress and Strain
• Effective Date: 01-Nov-2023
• Referred By: ASTM D6925-15 - Standard Test Method for Preparation and Determination of the Relative Density of Asphalt Mix Specimens by Means of the Superpave Gyratory Compactor
• Effective Date: 01-Nov-2023
• Referred By: ASTM D2726/D2726M-21 - Standard Test Method for Bulk Specific Gravity and Density of Non-Absorptive Compacted Asphalt Mixtures
• Effective Date: 01-Nov-2023
• Referred By: ASTM D6927-22 - Standard Test Method for Marshall Stability and Flow of Asphalt Mixtures
• Effective Date: 01-Nov-2023
• Referred By: ASTM D7115-20 - Standard Test Method for Measurement of Superpave Gyratory Compactor (SGC) Internal Angle of Gyration Using Simulated Loading
• Effective Date: 01-Nov-2023
• Referred By: ASTM D4460-22a - Standard Practice for Calculating Precision Limits Where Values Are Calculated from Other Test Methods
• Effective Date: 01-Nov-2023
• Referred By: ASTM D7981-20 - Standard Practice for Compaction of Prismatic Asphalt Specimens by Means of the Shear Box Compactor
• Effective Date: 01-Nov-2023
• Referred By: ASTM D7064/D7064M-21 - Standard Practice for Open-Graded Friction Course (OGFC) Asphalt Mixture Design
• Effective Date: 01-Nov-2023

Overview

ASTM D6752/D6752M-23 specifies the standard test method for determining the bulk specific gravity and density of compacted asphalt mixtures using the automatic vacuum sealing method. Developed by ASTM International, this method offers reliable procedures for testing cylindrical and cubical asphalt mixture specimens-both from laboratory and field sources.

This standard provides a means to accurately determine the unit weight and density of asphalt mixtures, correcting for inconsistencies in sample weight determinations that can arise from water drainage and inaccuracies in surface dry weight, particularly in absorptive or open-graded mixes. Results from this test are vital when assessing percent air voids and the relative degree of compaction of asphalt pavements, which influence pavement performance and durability.

Key Topics

• Purpose: Reliable measurement of the bulk specific gravity and density of compacted asphalt mixtures, including those with high surface texture or interconnected voids.
• Vacuum Sealing: Use of automatic vacuum sealing equipment improves accuracy by preventing moisture loss and ensuring consistent results, particularly for stone matrix asphalt (SMA), porous friction course, and coarse-graded mixes.
• Specimen Size: Suitable for both 100 mm [4 in.] and 150 mm [6 in.] diameter cylindrical specimens, as well as cubical samples.
• Calculation Guidance: The test distinguishes between specific gravity (unitless) and density (with units), providing instructions for converting specific gravity to density using the density of water at the relevant temperature.
• Applicability: The method supports both SI and inch-pound units, but these must not be mixed within a single analysis.
• Quality Assurance: Emphasis on equipment calibration, personnel competency, and following agency standards for reliable results.
• Sample Handling: Detailed instructions to avoid distortion and contamination, including recommendations for proper sampling, handling, and preparation of asphalt specimens.

Applications

• Asphalt Mix Design Verification: Essential in both laboratory and field environments to confirm asphalt mixture properties meet specified requirements.
• Construction Quality Control: Used to assess compaction quality by determining percent air voids in asphalt pavements, which is critical for predicting pavement lifespan and performance.
• Compatibility with Various Mixes: Ideal for mixes with significant surface texture, such as SMA, coarse-graded mixtures, and other absorptive asphalt types where conventional methods may yield inaccurate results.
• Research and Development: Supports agencies and researchers in evaluating new materials or construction methods by ensuring accurate measurement of bulk specific gravity and density.

Related Standards

For comprehensive asphalt mixture evaluation and to ensure compliance with quality protocols, the following related ASTM and referenced standards are essential complements to ASTM D6752/D6752M-23:

• ASTM D3203/D3203M: Test Method for Percent Air Voids in Compacted Asphalt Mixtures
• ASTM D2726/D2726M: Test Method for Bulk Specific Gravity and Density of Non-Absorptive Compacted Asphalt Mixtures
• ASTM D3666: Specification for Minimum Requirements for Agencies Testing and Inspecting Road and Paving Materials
• ASTM D5361/D5361M: Practice for Sampling Compacted Asphalt Mixtures for Laboratory Testing
• ASTM D8: Terminology Relating to Materials for Roads and Pavements

These standards, when used in conjunction, support robust quality assurance programs and enhance the reliability of pavement material evaluations.

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Keywords: ASTM D6752/D6752M-23, bulk specific gravity, asphalt density, vacuum sealing, compacted asphalt mixture, asphalt pavement testing, air voids, unit weight, stone matrix asphalt, quality control, asphalt construction standards.

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.
Designation: D6752/D6752M − 23
Standard Test Method for
Bulk Specific Gravity and Density of Compacted Asphalt
Mixtures Using Automatic Vacuum Sealing Method
This standard is issued under the fixed designation D6752/D6752M; 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 2. Referenced Documents
1.1 This test method covers the determination of bulk 2.1 ASTM Standards:
specific gravity of compacted asphalt mixtures by the vacuum C670 Practice for Preparing Precision and Bias Statements
sealing method. for Test Methods for Construction Materials
D8 Terminology Relating to Materials for Roads and Pave-
1.2 This method can be used for compacted cylindrical and
ments
cubical laboratory and field asphalt mixture specimens.
D2726/D2726M Test Method for Bulk Specific Gravity and
1.3 The bulk specific gravity of the compacted asphalt
Density of Non-Absorptive Compacted Asphalt Mixtures
mixtures may be used in calculating the unit weight of the
D3203/D3203M Test Method for Percent Air Voids in Com-
mixture.
pacted Asphalt Mixtures
1.4 The values stated in either SI units or inch-pound units D3666 Specification for Minimum Requirements for Agen-
cies Testing and Inspecting Road and Paving Materials
are to be regarded separately as standard. The values stated in
each system may not be exact equivalents; therefore, each D4753 Guide for Evaluating, Selecting, and Specifying Bal-
ances and Standard Masses for Use in Soil, Rock, and
system shall be used independently of the other. Combining
values from the two systems may result in nonconformance Construction Materials Testing
D5361/D5361M Practice for Sampling Compacted Asphalt
with the standard.
Mixtures for Laboratory Testing
1.5 The text of this standard references notes and footnotes
D7227/D7227M Practice for Rapid Drying of Compacted
which provide explanatory material. These notes and footnotes
Asphalt Mixture Specimens Using Vacuum Drying Appa-
(excluding those in tables and figures) shall not be considered
ratus
as requirements of the standard.
2.2 AASHTO Standard:
1.6 This standard does not purport to address all of the
M 323 Standard Specification for Superpave Mix Design
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
3. Terminology
priate safety, health, and environmental practices and deter-
3.1 For definitions of terms used in this standard, refer to
mine the applicability of regulatory limitations prior to use.
Terminology D8.
1.7 This international standard was developed in accor-
dance with internationally recognized principles on standard-
4. Significance and Use
ization established in the Decision on Principles for the
4.1 The results obtained from this method can be used to
Development of International Standards, Guides and Recom-
determine the unit weight of compacted asphalt mixtures, and
mendations issued by the World Trade Organization Technical
in conjunction with Test Method D3203/D3203M, to obtain
Barriers to Trade (TBT) Committee.
1 2
This test method is under the jurisdiction of ASTM Committee D04 on Road For referenced ASTM standards, visit the ASTM website, www.astm.org, or
and Paving Materials and is the direct responsibility of Subcommittee D04.21 on contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Specific Gravity and Density of Asphalt Mixtures. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Nov. 1, 2023. Published December 2023. Originally the ASTM website.
approved in 2002. Last previous edition approved in 2018 as D6752/D6752M – 18. Available from the American Association of State Highway Transportation
DOI: 10.1520/D6752_D6752M-23. Officials (AASHTO), 441 N. Capitol Street, NW, Washington, DC 20001.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6752/D6752M − 23
using a temperature-controlled heater. Also, to reduce the chance for the
percent air voids. These values in turn may be used in
bag to touch the sides of the water tank, it is preferable to elevate the water
determining the relative degree of compaction.
tank to a level at which the sample can be placed on the weighing
4.2 Since specific gravity has no units, it must be converted
mechanism while standing up, and the placement of the sample and the
bag in the water tank can easily be inspected.
to density in order to do calculations that require units. This
conversion is made by multiplying the specific gravity at a
5.3 Cushioned Holder, for water displacement of the
given temperature by the density of water at the same tempera-
sample, having no sharp edges.
ture.
NOTE 4—To avoid accidental puncture of the plastic bags in the water
4.3 This method can be used for 100 mm [4 in.] and bath, plastic-coated cushioned holders have been found to work well for
this test method.
150 mm [6 in.] diameter cylindrical as well as cubical asphalt
mixture specimens to correct for inconsistencies in sample
5.4 Vacuum Chamber, with a 0.93 kW [1.25 hp] pump,
weight determinations resulting from drainage of water from
capable of evacuating a sealed and enclosed chamber to a
samples and inaccuracy in saturated surface dry weight of
minimum pressure of 10 mm Hg [10 Torr] in less than 60 s
absorptive coarse and open-graded mixes. Asphalt mixes such
when at sea level. The chamber shall be large enough to seal
as stone matrix asphalt (SMA), porous friction course, and
samples of 150 mm [6 in.] wide by 350 mm [14 in.] long by
coarse-graded mixes with significant surface texture and inter-
150 mm [6 in.] thick. The device shall automatically seal the
connected voids can be tested with this method. Follow
plastic bag and exhaust air back into the chamber in a
manufacturer recommendation for appropriate bag sizes to be
controlled manner to ensure proper conformance of the plastic
utilized with cubical and abnormally shaped samples.
to the asphalt specimen. The air exhaust and vacuum operation
time should be calibrated at the factory prior to initial use. The
NOTE 1—The quality of the results produced by this standard are
air exhaust system should be calibrated to bring the chamber to
dependent on the competence of the personnel performing the procedure
and the capability, calibration, and maintenance of the equipment used. atmospheric pressure in 80 to 120 s, after the completion of the
Agencies that meet the criteria of Specification D3666 are generally
vacuum operation. The vacuum system should be provided
considered capable of competent and objective testing, sampling,
with a latch to control the chamber door opening.
inspection, etc. Users of this standard are cautioned that compliance with
Specification D3666 alone does not completely ensure reliable results.
5.5 Vacuum Measurement Gauge, independent of the
Reliable results depend on many factors; following the suggestions of
vacuum sealing device that could be placed directly inside the
Specification D3666 or some similar acceptable guideline provides a
chamber, to verify vacuum performance and the chamber door
means of evaluating and controlling some of those factors.
sealing condition of the unit. The gauge shall be capable of
reading 3 mm Hg [3 Torr] pressure.
5. Apparatus
5.6 Plastic Bags, used with the vacuum device, shall be one
5.1 Balance, with ample capacity, and with sufficient sensi-
of the two following sizes. The smaller bags shall have a
tivity to enable bulk specific gravity of specimens to be
minimum opening of 235 mm [9.25 in.] and maximum opening
calculated to at least four significant figures, that is, to at least
of 267 mm [10.50 in.], and the larger bags shall have a
three decimal places. It shall be equipped with a suitable
minimum of 368 mm [14.50 in.] and a maximum opening of
apparatus to permit weighing the specimen while it is sus-
394 mm [15.5 in.]. The bags shall be of plastic material that
pended in water. The balance shall conform to Guide D4753 as
will not adhere to asphalt film, is puncture resistant, is capable
a class GP2 balance.
of withstanding sample temperatures of up to 70 °C [158 °F],
NOTE 2—Since there are no more significant figures in the quotient
is impermeable to water, and contains no air channels for
(bulk specific gravity) than appear in either the dividend (the mass of the
evacuation of air from the bag. The bags shall have a minimum
specimen in air) or in the divisor (the volume of the specimen obtained
from the difference in mass of the specimen in air and in water), this thickness of 0.102 mm [0.004 in.] and maximum thickness of
means that the balance must have a sensitivity capable of providing both
0.178 mm [0.007 in.]. The apparent specific gravity for the
mass and volume values to at least four figures. For example, a sensitivity
bags shall be provided by the manufacturer. The apparent
of 0.1 g [0.00022 lb] would provide four significant figures for the
specific gravity provided for each size bag shall account for the
determination of a mass in the range from 130.0 to 999.9 g [0.29 to
different sample weights and bag weight used during testing.
2.20 lb] when the specific gravity is 2.300.
5.7 Specimen Sliding Plate, used within the chamber for
5.2 Water Bath, with minimum dimensions (length × width
reduction of friction on the plastic bags.
× depth) of 610 by 460 by 460 mm [24 by 18 by 18 in.] or a
large cylindrical container, for completely submerging the
5.8 Bag-Cutting Knife, or scissors.
specimen in water while suspended, equipped with an overflow
outlet for maintaining a constant water level.
6. Sampling
NOTE 3—It is preferable to keep the water temperature constant by
6.1 Test specimens may be molded from laboratory-
prepared samples or taken from asphalt pavement in the field.
Field samples should be obtained in accordance with Practice
Bulk specific gravity determined by this method may be lower than the results
D5361/D5361M.
obtained by Test Method D2726/D2726M. As a result, air voids determined from
these bulk specific gravity values may be higher than the air voids values determined
using Test Method D2726/D2726M. These differences may be more pronounced for 7. Test Specimens
coarse aggregate mixtures. Users of this method are cautioned to evaluate any
7.1 It is recommended (1) that the diameter of cylindrically
alteration in percent asphalt content or aggregate gradations for mix designs with a
known positive performance history. molded or
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D6752/D6752M − 18 D6752/D6752M − 23
Standard Test Method for
Bulk Specific Gravity and Density of Compacted Asphalt
Mixtures Using Automatic Vacuum Sealing Method
This standard is issued under the fixed designation D6752/D6752M; 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 This test method covers the determination of bulk specific gravity of compacted asphalt mixtures by the vacuum sealing
method.
1.2 This method can be used for compacted cylindrical and cubical laboratory and field asphalt mixture specimens.
1.3 The bulk specific gravity of the compacted asphalt mixtures may be used in calculating the unit weight of the mixture.
1.4 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 nonconformance with the standard.
1.5 The text of this standard references notes and footnotes which provide explanatory material. These notes and footnotes
(excluding those in tables and figures) shall not be considered as requirements of the standard.
1.6 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, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.7 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
D8 Terminology Relating to Materials for Roads and Pavements
D2726/D2726M Test Method for Bulk Specific Gravity and Density of Non-Absorptive Compacted Asphalt Mixtures
D3203/D3203M Test Method for Percent Air Voids in Compacted Asphalt Mixtures
D3666 Specification for Minimum Requirements for Agencies Testing and Inspecting Road and Paving Materials
This test method is under the jurisdiction of ASTM Committee D04 on Road and Paving Materials and is the direct responsibility of Subcommittee D04.21 on Specific
Gravity and Density of Asphalt Mixtures.
Current edition approved Aug. 15, 2018Nov. 1, 2023. Published August 2018December 2023. Originally approved in 2002. Last previous edition approved in 20172018
as D6752/D6752M – 17.D6752/D6752M – 18. DOI: 10.1520/D6752_D6752M-18.10.1520/D6752_D6752M-23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6752/D6752M − 23
D4753 Guide for Evaluating, Selecting, and Specifying Balances and Standard Masses for Use in Soil, Rock, and Construction
Materials Testing
D5361/D5361M Practice for Sampling Compacted Asphalt Mixtures for Laboratory Testing
D7227/D7227M Practice for Rapid Drying of Compacted Asphalt Mixture Specimens Using Vacuum Drying Apparatus
2.2 AASHTO Standard:
M323M 323 Standard Specification for Superpave Mix Design
3. Terminology
3.1 For definitions of terms used in this standard, refer to Terminology D8.
4. Significance and Use
4.1 The results obtained from this method can be used to determine the unit weight of compacted asphalt mixtures, and in
conjunction with Test Method D3203/D3203M, to obtain percent air voids. These values in turn may be used in determining the
relative degree of compaction.
4.2 Since specific gravity has no units, it must be converted to density in order to do calculations that require units. This conversion
is made by multiplying the specific gravity at a given temperature by the density of water at the same temperature.
4.3 This method can be used for 100 mm [4 in.] and 150 mm [6 in.] diameter cylindrical as well as cubical asphalt mixture
specimens to correct for inconsistencies in sample weight determinations resulting from drainage of water from samples and
inaccuracy in saturated surface dry weight of absorptive coarse and open-graded mixes. Asphalt mixes such as stone matrix asphalt
(SMA), porous friction course, and coarse-graded mixes with significant surface texture and interconnected voids can be tested
with this method. Follow manufacturer recommendation for appropriate bag sizes to be utilized with cubical and abnormally
shaped samples.
NOTE 1—The quality of the results produced by this standard are dependent on the competence of the personnel performing the procedure and the
capability, calibration, and maintenance of the equipment used. Agencies that meet the criteria of Specification D3666 are generally considered capable
of competent and objective testing, sampling, inspection, etc. Users of this standard are cautioned that compliance with Specification D3666 alone does
not completely ensure reliable results. Reliable results depend on many factors; following the suggestions of Specification D3666 or some similar
acceptable guideline provides a means of evaluating and controlling some of those factors.
5. Apparatus
5.1 Balance, with ample capacity, and with sufficient sensitivity to enable bulk specific gravity of specimens to be calculated to
at least four significant figures, that is, to at least three decimal places. It shall be equipped with a suitable apparatus to permit
weighing the specimen while it is suspended in water. The balance shall conform to Guide D4753 as a class GP2 balance.
NOTE 2—Since there are no more significant figures in the quotient (bulk specific gravity) than appear in either the dividend (the mass of the specimen
in air) or in the divisor (the volume of the specimen,specimen obtained from the difference in mass of the specimen in air and in water), this means that
the balance must have a sensitivity capable of providing both mass and volume values to at least four figures. For example, a sensitivity of 0.1 g [0.00022
lb] would provide four significant figures for the determination of a mass in the range from 130.0 to 999.9 g [0.29 to 2.20 lb] when the specific gravity
is 2.300.
5.2 Water Bath, with minimum dimensions (length × width × depth) of 610 by 460 by 460 mm [24 by 18 by 18 in.] or a large
cylindrical container, for completely submerging the specimen in water while suspended, equipped with an overflow outlet for
maintaining a constant water level.
NOTE 3—It is preferable to keep the water temperature constant by using a temperature-controlled heater. Also, to reduce the chance for the bag to touch
the sides of the water tank, it is preferable to elevate the water tank to a level at which the sample can be placed on the weighing mechanism while standing
up, and the placement of the sample and the bag in the water tank can easily be inspected.
Available from the American Association of State Highway Transportation Officials (AASHTO), 441 N. Capitol Street, NW, Washington, DC 20001.
Bulk specific gravity determined by this method may be lower than the results obtained by Test Method D2726/D2726M. As a result, air voids determined from these
bulk specific gravity values may be higher than the air voids values determined using Test Method D2726/D2726M. These differences may be more pronounced for coarse
aggregate mixtures. Users of this method are cautioned to evaluate any alteration in percent asphalt content or aggregate gradations for mix designs with a known positive
performance history.
D6752/D6752M − 23
5.3 Cushioned Holder, for water displacement of the sample, having no sharp edges.
NOTE 4—To avoid accidental puncture of the plastic bags in the water bath, plastic-coated cushioned holders have been found to work well for this test
method.
5.4 Vacuum Chamber, with a 0.93-kW [1.25-hp] pump 0.93 kW [1.25 hp] pump, capable of evacuating a sealed and enclosed
chamber to a minimum pressure of 10 mm Hg [10 Torr] in less than 60 s, 60 s when at sea level. The chamber shall be large enough
to seal samples of 150 mm [6 in.] wide by 350 mm [14 in.] long by 150 mm [6 in.] thick. The device shall automatically seal the
plastic bag and exhaust air back into the chamber in a controlled manner to ensure proper conformance of the plastic to the asphalt
specimen. The air exhaust and vacuum operation time should be calibrated at the factory prior to initial use. The air exhaust system
should be calibrated to bring the chamber to atmospheric pressure in 80 to 120 s, after the completion of the vacuum operation.
The vacuum system should be provided with a latch to control the chamber door opening.
5.5 Vacuum Measurement Gauge, independent of the vacuum sealing device that could be placed directly inside the chamber, to
verify vacuum performance and the chamber door sealing condition of the unit. The gauge shall be capable of reading 3 mm Hg
[3 Torr] pressure.
5.6 Plastic Bags, used with the vacuum device, shall be one of the two following sizes. The smaller bags shall have a minimum
opening of 241 mm [9.50235 mm [9.25 in.] and maximum opening of 267 mm [10.50 in.], and the larger bags shall have a
minimum of 368 mm [14.50 in.] and a maximum opening of 394 mm [15.5 in.]. The bags shall be of plastic material that will not
adhere to asphalt film, is puncture resistant, is capable of withstanding sample temperatures of up to 70 °C [158 °F], is
impermeable to water, and contains no air channels for evacuation of air from the bag. The bags shall have a minimum thickness
of 0.127 mm [0.0050.102 mm [0.004 in.] and maximum thickness of 0.178 mm [0.007 in.]. The apparent specific gravity for the
bags shall be provided by the manufacturer. The apparent specific gravity provided for each size bag shall account for the different
sample weights and bag weight used during testing.
5.7 Specimen Sliding Plate, used within the chamber for reduction of friction on the plastic bags.
5.8 Bag-Cutting Knife, or scissors.
6. Sampling
6.1 Test specimens may be molded from laboratory-prepared samples or taken from asphalt pavement in the field. Field samples
should be obtained in accordance with Practice D5361/D5361M.
7. Test Specimens
7.1 It is r
...