ASTM D7115-20

Standard Test Method for Measurement of Superpave Gyratory Compactor (SGC) Internal Angle of Gyration Using Simulated Loading

SIGNIFICANCE AND USE
5.1 SGCs are used to produce asphalt mixture specimens in the laboratory to assess volumetric properties and predict pavement performance. In the fabrication of an SGC specimen in accordance with Test Method D6925, loose asphalt mixture is placed inside a metal mold, which is then placed into an SGC. A constant consolidation pressure is applied to the sample while the mold gyrates at a nominally constant angle (referred to as the internal angle of gyration) and rate. Consistency in the density of the asphalt specimens produced as measured by Test Method D2726/D2726M or D6752/D6752M is very important to the validity of the tests performed. Specimens of a consistent density are produced when an SGC maintains a constant pressure and a known constant internal angle of gyration during the compaction process.  
5.2 There are several manufacturers and models of SGC. Each model employs a unique method of setting, inducing, and maintaining the internal angle of gyration. Each model also employs a unique calibration system to measure the external angle of gyration. These existing calibration systems cannot be used universally on all of the different SGC models commercially available. Inconsistencies in asphalt specimens produced on different SGC models have been at least partially attributed to variations in the angle of gyration.  
5.3 This method describes instruments and processes that can be used to independently measure the internal angle of gyration of any manufacturer’s SGC model under simulated loading conditions. The external shape of the instrument chassis ensures that the points of physical contact between the mold end plates and the instrument occur at a fixed and known distance away from the axis of gyration. As a result, the vertical load is applied at these fixed points, creating tilting moments at each end of the mold.  
5.4 Unless otherwise specified, a tilting moment of 466.5 N-m shall be applied to the SGC by the instrument while making this measurement....
SCOPE
1.1 This test method covers the procedure for the measurement of the Superpave Gyratory Compactor (SGC) internal angle of gyration using an instrument capable of simulating loading conditions similar to those created by an asphalt mixture specimen.  
1.2 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. The value given in rotations per minute is provided for information regarding commonly used units.  
1.2.1 IEEE/ASTM SI 10, American National Standard for Metric Practice, offers guidance where use of decimal degrees for plane angles (versus radians) and revolutions per minute for rate of gyration (versus radians per second) is acceptable within the IEEE/ASTM SI 10 system when used on a minimal basis.  
1.3 The text of this test method 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  
1.4 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
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.

General Information

• Status: Published
• Publication Date: 30-Apr-2020
• ICS: 93.080.20 - Road construction materials
• Technical Committee: D04 - Road and Paving Materials
• Drafting Committee: D04.20 - Mechanical Tests of Asphalt Mixtures

Relations

• Replaces: ASTM D7115-10(2015) - Standard Test Method for Measurement of Superpave Gyratory Compactor (SGC) Internal Angle of Gyration Using Simulated Loading
• Effective Date: 01-May-2020
• 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 D6925-23 - 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-Dec-2023
• Refers: ASTM D6752/D6752M-23 - 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 D8-19 - Standard Terminology Relating to Materials for Roads and Pavements
• Effective Date: 01-Aug-2019
• Refers: ASTM D8-18c - Standard Terminology Relating to Materials for Roads and Pavements
• Effective Date: 15-Dec-2018
• Refers: ASTM D6752/D6752M-18 - Standard Test Method for Bulk Specific Gravity and Density of Compacted Asphalt Mixtures Using Automatic Vacuum Sealing Method
• Effective Date: 15-Aug-2018
• Refers: ASTM D8-18b - Standard Terminology Relating to Materials for Roads and Pavements
• Effective Date: 15-Aug-2018
• Refers: ASTM D8-18a - Standard Terminology Relating to Materials for Roads and Pavements
• Effective Date: 01-Jul-2018
• Refers: ASTM D8-18 - Standard Terminology Relating to Materials for Roads and Pavements
• Effective Date: 01-Feb-2018
• Refers: ASTM D8-17c - Standard Terminology Relating to Materials for Roads and Pavements
• Effective Date: 15-Jul-2017
• Refers: ASTM D8-17b - Standard Terminology Relating to Materials for Roads and Pavements
• Effective Date: 15-Jun-2017
• Refers: ASTM D6752/D6752M-17 - Standard Test Method for Bulk Specific Gravity and Density of Compacted Asphalt Mixtures Using Automatic Vacuum Sealing Method
• Effective Date: 01-Jun-2017
• Refers: ASTM D2726/D2726M-17 - Standard Test Method for Bulk Specific Gravity and Density of Non-Absorptive Compacted Asphalt Mixtures
• Effective Date: 01-Jun-2017

Overview

ASTM D7115-20: Standard Test Method for Measurement of Superpave Gyratory Compactor (SGC) Internal Angle of Gyration Using Simulated Loading provides a standardized procedure for determining the internal angle of gyration in Superpave Gyratory Compactors (SGCs) under conditions that simulate actual asphalt mixture compaction. Ensuring the consistency and accuracy of this internal angle is critical for producing reliable laboratory asphalt mix specimens, which in turn are foundational for assessing volumetric properties and predicting pavement performance.

Maintaining a precise internal angle of gyration during compaction directly affects the density and quality of asphalt specimens, influencing the integrity of subsequent performance testing.

Key Topics

• SGC Internal Angle Measurement
  Defines how to measure the internal angle of gyration within the mold of a Superpave Gyratory Compactor using a specialized instrument under simulated loading conditions.

• Simulated Loading Protocol
  Describes the induction of a specified tilting moment (normally 466.5 N-m) to replicate the stresses experienced during hot mix asphalt (HMA) compaction.

• Instrument and Calibration
  Outlines requirements for the measurement apparatus, including calibration using a NIST-traceable static angle gage and periodic verification to ensure measurement accuracy.

• Multiple Compactor and Instrument Compatibility
  Provides a method adaptable to various SGC models and brands, addressing the lack of universal calibration systems among different manufacturers.

• Measurement Process
  Specifies procedures for measuring top and bottom internal angles, averaging results, and recording all relevant test information to ensure repeatability and traceability.

Applications

The ASTM D7115-20 standard test method offers significant benefits for:

• Testing Laboratories
  Ensures that SGCs provide consistent compaction characteristics, directly supporting laboratory quality assurance and performance-based pavement evaluation.

• Pavement Material Specification
  Provides a reliable means of verifying that compactors across different plants and laboratories operate with comparable internal angles, improving confidence in mix designs and performance predictions.

• Manufacturers and Calibrators of SGCs
  Offers a standardized procedure for verifying and certifying the performance of each compactor, which is essential for inter-laboratory consistency and equipment compliance.

• Quality Control for Road Construction
  Enables agencies and contractors to identify and mitigate variability in compacted asphalt specimens, supporting better road durability and lifecycle outcomes.

Related Standards

• ASTM D6925: Test Method for Preparation and Determination of the Relative Density of Asphalt Mix Specimens by the Superpave Gyratory Compactor.
• ASTM D2726/D2726M: Test Method for Bulk Specific Gravity and Density of Non-Absorptive Compacted Asphalt Mixtures.
• ASTM D6752/D6752M: Test Method for Bulk Specific Gravity and Density of Compacted Asphalt Mixtures Using Automatic Vacuum Sealing.
• ASTM D3666: Specification for Minimum Requirements for Agencies Testing and Inspecting Road and Paving Materials.
• IEEE/ASTM SI 10: American National Standard for Metric Practice.

By following ASTM D7115-20, laboratories and agencies ensure standardized, accurate measurement of the internal angle of gyration, thereby delivering reliable data for asphalt mix design and performance assessment. This standard underpins confidence in asphalt quality across the paving industry and supports compliance with international best practices.

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: D7115 − 20
Standard Test Method for
Measurement of Superpave Gyratory Compactor (SGC)
Internal Angle of Gyration Using Simulated Loading
This standard is issued under the fixed designation D7115; 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 procedure for the measure- 2.1 ASTM Standards:
ment of the Superpave Gyratory Compactor (SGC) internal C670 Practice for Preparing Precision and Bias Statements
angle of gyration using an instrument capable of simulating for Test Methods for Construction Materials
loading conditions similar to those created by an asphalt D8 Terminology Relating to Materials for Roads and Pave-
mixture specimen. ments
D2726/D2726M Test Method for Bulk Specific Gravity and
1.2 Units—The values stated in SI units are to be regarded
Density of Non-Absorptive Compacted Asphalt Mixtures
as standard. No other units of measurement are included in this
D3666 Specification for Minimum Requirements for Agen-
standard. The value given in rotations per minute is provided
cies Testing and Inspecting Road and Paving Materials
for information regarding commonly used units.
D6752/D6752M Test Method for Bulk Specific Gravity and
1.2.1 IEEE/ASTM SI 10, American National Standard for
Density of CompactedAsphalt Mixtures UsingAutomatic
Metric Practice, offers guidance where use of decimal degrees
Vacuum Sealing Method
forplaneangles(versusradians)andrevolutionsperminutefor
D6925 Test Method for Preparation and Determination of
rate of gyration (versus radians per second) is acceptable
the Relative Density ofAsphalt Mix Specimens by Means
within the IEEE/ASTM SI 10 system when used on a minimal
of the Superpave Gyratory Compactor
basis.
E691 Practice for Conducting an Interlaboratory Study to
1.3 The text of this test method references notes and
Determine the Precision of a Test Method
footnotes which provide explanatory material. These notes and
IEEE/ASTM SI 10 American National Standard for Metric
footnotes (excluding those in tables and figures) shall not be
Practice
considered as requirements of the standard
1.4 This standard does not purport to address all of the 3. Terminology
safety concerns, if any, associated with its use. It is the
3.1 Definitions—For definitions of terms used in this test
responsibility of the user of this standard to establish appro-
method, refer to Terminology D8.
priate safety, health, and environmental practices and deter-
3.2 Definitions of Terms Specific to This Standard:
mine the applicability of regulatory limitations prior to use.
3.2.1 bottom internal angle, n—the angle formed between
1.5 This international standard was developed in accor-
the internal mold diameter and the lower mold end plate as a
dance with internationally recognized principles on standard-
mold is gyrated in an SGC.
ization established in the Decision on Principles for the
3.2.2 eccentricity, e, n—the distance away from the axis of
Development of International Standards, Guides and Recom-
gyration at which a force (F) is acting at one end of an SGC
mendations issued by the World Trade Organization Technical
mold.
Barriers to Trade (TBT) Committee.
3.2.2.1 Discussion—This use of the term eccentricity is
This test method is under the jurisdiction of ASTM Committee D04 on Road
and Paving Materials and is the direct responsibility of Subcommittee D04.20 on
Mechanical Tests of Asphalt Mixtures. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved May 1, 2020. Published May 2020. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 2005. Last previous edition approved in 2015 as D7115 – 10 (2015). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D7115-20. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7115 − 20
consistent with previous published reports describing the an SGC maintains a constant pressure and a known constant
mechanics of gyratory compaction. internal angle of gyration during the compaction process.
3.2.3 effective internal angle, n—the average of the top
5.2 There are several manufacturers and models of SGC.
internal angle and the bottom internal angle.
Each model employs a unique method of setting, inducing, and
maintaining the internal angle of gyration. Each model also
3.2.4 external angle, n—the angle formed between the
employs a unique calibration system to measure the external
external mold diameter and a stationary reference axis of the
angle of gyration.These existing calibration systems cannot be
machine frame as a mold is gyrated in the SGC.
used universally on all of the different SGC models commer-
3.2.5 internal angle, n—the angle formed between the
cially available. Inconsistencies in asphalt specimens produced
internal mold diameter and a mold end plate as a mold is
on different SGC models have been at least partially attributed
gyrated in an SGC.
to variations in the angle of gyration.
3.2.6 standard SGC volumetric specimen, n—a standard
5.3 This method describes instruments and processes that
sized asphalt mixture specimen prepared using an SGC for
can be used to independently measure the internal angle of
purposes of volumetric mix design.
gyration of any manufacturer’s SGC model under simulated
3.2.6.1 Discussion—Such a standard specimen, prepared in
loading conditions. The external shape of the instrument
accordance with Test Method D6925, has a diameter of
chassis ensures that the points of physical contact between the
150 mm and a final compacted height of 115 6 5 mm.
mold end plates and the instrument occur at a fixed and known
3.2.7 tilting moment, n—a force (F) acting at one end of an
distanceawayfromtheaxisofgyration.Asaresult,thevertical
SGC mold platen in a direction parallel to the axis of gyration,
load is applied at these fixed points, creating tilting moments at
but acting at some distance (e) away from that axis. The tilting
each end of the mold.
moment at one end of the mold platen is computed as the
5.4 Unless otherwise specified, a tilting moment of
product of this distance (e) and force (F).
466.5 N-m shall be applied to the SGC by the instrument while
3.2.8 top internal angle, n—the angle formed between the
making this measurement.
internal mold diameter and the upper mold end plate as a mold
is gyrated in an SGC. NOTE 1—The quality of the results produced by this test method are
dependent on the competence of the personnel performing the procedure
3.2.9 total moment, M, n—the sum total of the tilting
and the capability, calibration, and maintenance of the equipment used.
moment acting at the top of the mold and the tilting moment
Agencies that meet the criteria of Specification D3666 are generally
acting at the bottom of the mold. considered capable of competent and objective testing, sampling,
inspection, etc. Users of this test method are cautioned that compliance
with Specification D3666 alone does not completely ensure reliable
4. Summary of Test Method
results. Reliable results depend on many factors; following the sugges-
4.1 The internal angle of gyration of an SGC is measured
tions of Specification D3666 or some similar acceptable guideline
dynamically with an instrument inserted into the SGC mold.
provides a means of evaluating and controlling some of those factors.
NOTE 2—A 466.5 N-m tilting moment corresponds to a 22 mm
4.2 A load (moment) is induced on the SGC while the
eccentric on the AFLS1 or a 21° cone angle on the DAVII-HMS with an
internal angle is simultaneously measured. The simulated
applied load of 10603 N (600 kPa at a 150 mm diameter specimen
loading conditions are similar to those created by compaction
setting).
of a standard SGC volumetric specimen.
6. Interferences
4.3 The internal angles at each end of the mold are mea-
suredandthenaveragedtoobtaintheeffectiveinternalangleof 6.1 DebrisontheSGCmold,baseplates,ramhead,reaction
gyration.
surfaces, or instrument can cause errant measurement results.
Extreme care should be taken to thoroughly clean the SGC,
5. Significance and Use
mold, instrument, and any work areas that will be utilized
during the measurement procedure.
5.1 SGCs are used to produce asphalt mixture specimens in
the laboratory to assess volumetric properties and predict
6.2 Scarring or irregular surfaces on mold walls and end
pavement performance. In the fabrication of an SGC specimen
plates is also known to cause incorrect results. Do not use any
in accordance with Test Method D6925, loose asphalt mixture
equipment that shows signs of damage. The precision required
is placed inside a metal mold, which is then placed into an
in the execution of this test method necessitates that extreme
SGC. A constant consolidation pressure is applied to the
caremustbetakentoavoiderrorsfromdamagedorimproperly
sample while the mold gyrates at a nominally constant angle
maintained equipment.
(referred to as the internal angle of gyration) and rate.
6.3 Worn parts on the instrument can lead to erroneous
Consistency in the density of the asphalt specimens produced
measurements.
as measured by Test Method D2726/D2726M or D6752/
D6752M is very important to the validity of the tests per-
7. Apparatus
formed. Specimens of a consistent density are produced when
7.1 An instrument capable of being gyrated inside an SGC
mold which induces tilting moments at each end of the SGC
Guler, M., Bahia, H. U., Bosscher, P. J., and Plesha, M. E., “Device for
mold while simultaneously measuring an internal angle of
Measuring Shear Resistance of Hot Mix Asphalt in Gyratory Compactor,” Trans-
portation Research Record, Vol 1723, No. 1, 2000, pp. 116–124. gyration.
D7115 − 20
7.1.1 Data Acquisition—The timing of the data acquisition in the oven. Mold temperatures other than room temperature
system may be automatically triggered by the start of the used during angle measurement shall be noted on the report.
NOTE 5—The SGC manufacturer may recommend measurement of the
gyration process. Provision for excluding a known number of
angle at an elevated temperature for those SGC models where the angle
initial gyrations from the angle measurement may be provided
changes with mold temperature.
(initial delay period), and the angle shall be measured through-
NOTE 6—These instruments typically have an operating temperature
out a known number of subsequent gyrations (data acquisition
range of 20 to 40 °C. After use in a hot mol
...

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: D7115 − 10 (Reapproved 2015) D7115 − 20
Standard Test Method for
Measurement of Superpave Gyratory Compactor (SGC)
Internal Angle of Gyration Using Simulated Loading
This standard is issued under the fixed designation D7115; 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 procedure for the measurement of the Superpave Gyratory Compactor (SGC) internal angle of
gyration using an instrument capable of simulating loading conditions similar to those created by a hot mix asphalt an asphalt
mixture specimen.
1.2 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this
standard. The value given in rotations per minute is provided for information regarding commonly used units.
1.2.1 IEEE/ASTM SI 10, American National Standard for the Use of International System of Units (SI): The Modern Metric
System,Metric Practice, offers guidance where use of decimal degrees for plane angles (versus radians) and revolutions per minute
for rate of gyration (versus radians per second) is acceptable within the IEEE/ASTM SI 10 system when used on a minimal basis.
1.3 The text of this test method 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
1.4 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.
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
D8 Terminology Relating to Materials for Roads and Pavements
D2726D2726/D2726M Test Method for Bulk Specific Gravity and Density of Non-Absorptive Compacted Asphalt Mixtures
D3666 Specification for Minimum Requirements for Agencies Testing and Inspecting Road and Paving Materials
D6752D6752/D6752M Test Method for Bulk Specific Gravity and Density of Compacted Asphalt Mixtures Using Automatic
Vacuum Sealing Method
D6925 Test Method for Preparation and Determination of the Relative Density of Asphalt Mix Specimens by Means of the
Superpave Gyratory Compactor
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
IEEE/ASTM SI 10 American National Standard for the Use of International System of Units (SI): The Modern Metric
SystemMetric Practice
3. Terminology
3.1 Definitions—For definitions of terms used in this test method, refer to Terminology D8.
3.2 Definitions:Definitions of Terms Specific to This Standard:
This test method is under the jurisdiction of ASTM Committee D04 on Road and Paving Materials and is the direct responsibility of Subcommittee D04.20 on Mechanical
Tests of Asphalt Mixtures.
Current edition approved Dec. 1, 2015May 1, 2020. Published February 2016May 2020. Originally approved in 2005. Last previous edition approved in 20102015 as
D7115 – 10.D7115 – 10 (2015). DOI: 10.1520/D7115-10R15.10.1520/D7115-20.
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
D7115 − 20
3.2.1 bottom internal angle, n—the angle formed between the internal mold diameter and the lower mold end plate as a mold
is gyrated in an SGC.
3.2.2 eccentricity, e, n—the distance away from the axis of gyration at which a force (F) is acting at one end of an SGC mold.
3.2.2.1 Discussion—
This use of the term eccentricity is consistent with previous published reports describing the mechanics of gyratory compaction.
3.2.3 effective internal angle, n—the average of the top internal angle and the bottom internal angle.
3.2.4 external angle—angle, n—the angle formed between the external mold diameter and a stationary reference axis of the
machine frame.frame as a mold is gyrated in the SGC.
3.2.5 internal angle—angle, n—the angle formed between the internal mold diameter and a mold end plate as a mold is gyrated
in an SGC.
3.2.6 top internal angle—standard SGC volumetric specimen, n—the angle formed between the internal mold diameter and the
upper mold end plate as a mold is gyrated in an SGC.a standard sized asphalt mixture specimen prepared using an SGC for
purposes of volumetric mix design.
3.2.6.1 Discussion—
Such a standard specimen, prepared in accordance with Test Method D6925, has a diameter of 150 mm and a final compacted
height of 115 6 5 mm.
3.1.4 bottom internal angle—the angle formed between the internal mold diameter and the lower mold end plate as a mold is
gyrated in an SGC.
3.1.5 effective internal angle—the average of the top internal angle and the bottom internal angle.
3.2.7 tilting moment—moment, n—a force (F) acting at one end of an SGC mold platen in a direction parallel to the axis of
gyration, but acting at some distance (e) away from that axis. The tilting moment at one end of the mold platen is computed as
the product of this distance (e) and force (F).
3.2.8 top internal angle, n—the angle formed between the internal mold diameter and the upper mold end plate as a mold is
gyrated in an SGC.
3.2.9 total moment—moment, M, n—the sum total (M) of the tilting moment acting at the top of the mold and the tilting moment
acting at the bottom of the mold.
3.1.8 eccentricity—the distance (e) away from the axis of gyration at which a force (F) is acting at one end of an SGC mold.
This use of the term eccentricity is consistent with previous published reports describing the mechanics of gyratory compaction.
3.1.9 standard SGC volumetric specimen—a standard sized hot mix asphalt specimen prepared using an SGC for purposes of
volumetric mix design. Such a standard specimen, prepared in accordance with Test Method D6925, has a diameter of 150 mm
and a final compacted height of 115 6 5 mm.
4. Summary of Test Method
4.1 The internal angle of gyration of an SGC is measured dynamically with an instrument inserted into the SGC mold.
4.2 A load (moment) is induced on the SGC while the internal angle is simultaneously measured. The simulated loading
conditions are similar to those created by compaction of a standard SGC volumetric specimen.
4.3 The internal angles at each end of the mold are measured and then averaged to obtain the effective internal angle of gyration.
5. Significance and Use
5.1 SGCs are used to produce hot-mix asphalt (HMA)mixture specimens in the laboratory to assess volumetric properties and
predict pavement performance. In the fabrication of an SGC specimen in accordance with Test Method D6925, loose HMA asphalt
mixture is placed inside a metal mold, which is then placed into an SGC. A constant consolidation pressure is applied to the sample
while the mold gyrates at a nominally constant angle (referred to as the internal angle of gyration) and rate. Consistency in the
density of the asphalt specimens produced as measured by Test MethodsMethod D2726D2726/D2726M or D6752D6752/D6752M
is very important to the validity of the tests performed. Specimens of a consistent density are produced when an SGC maintains
a constant pressure and a known constant internal angle of gyration during the compaction process.
Guler, M., Bahia,Bahia, H. U., Bosscher,Bosscher, P. J., and Plesha,Plesha, M. E., “Device“Device for Measuring Shear Resistance of Hot Mix Asphalt in Gyratory
Compactor,” Transportation Research Recordfor Measuring, Vol 1723Shear Resistance, No. 1of Hot Mix Asphalt in Gyratory Compactor,”, Transportation Research Record
1723, TRB, National Academy of Sciences, Washington, DC, 2000, pp. 116–124.
D7115 − 20
5.2 There are several manufacturers and models of SGC. Each model employs a unique method of setting, inducing, and
maintaining the internal angle of gyration. Each model also employs a unique calibration system to measure the external angle of
gyration. These existing calibration systems can not cannot be used universally on all of the different SGC models commercially
available. Inconsistencies in asphalt specimens produced on different SGC models have been at least partially attributed to
variations in the angle of gyration.
5.3 This method describes instruments and processes that can be used to independently measure the internal angle of gyration
of any manufacturers’manufacturer’s SGC model under simulated loading conditions. The external shape of the instrument chassis
assuresensures that the points of physical contact between the mold end plates and the instrument occur at a fixed and known
distance away from the axis of gyration. As a result, the vertical load is applied at these fixed points, creating tilting moments at
each end of the mold.
5.4 Unless otherwise specified, a tilting moment of 466.5 N-m 466.5 N-m shall be applied to the SGC by the instrument while
making this measurement.
NOTE 1—The quality of the results produced by this test method 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 PracticeSpecification D3666 are generally considered
capable of competent and objective testing/sampling/inspection/etc. testing, sampling, inspection, etc. Users of this test method are cautioned that
compliance with PracticeSpecification D3666 alone does not completely assureensure reliable results. Reliable results depend on many factors; following
the suggestions of PracticeSpecification D3666 or some similar acceptable guideline provides a means of evaluating and controlling some of those factors.
NOTE 2—A 466.5 N-m tilting moment corresponds to a 22 mm eccentric on the AFLS1 or a 21 deg 21° cone angle on the DAVII-HMS with an applied
load of 10603 N (600 kPa at a 150 mm diameter specimen setting).
6. Interferences
6.1 Debris on the SGC mold, base plates, ram head, reaction surfaces, or instrument can cause errant measurement results.
Extreme care should be taken to thoroughly clean the SGC, mold, instrument, and any work areas that will be utilized during the
measurement procedure.
6.2 Scarring or irregular surfaces on mold walls and end plates is also known to cause incorrect results. Do not use any
equipment that shows signs of damage. The precision required in the execution of this test method necessitates that extreme care
must be taken to avoid errors from damaged or improperly maintained equipment.
6.3 Worn parts on the instrument can lead to erroneous measurements.
7. Apparatus
7.1 An instrument capable of being gyrated inside an SGC mold which induces tilting moments at each end of the SGC mold
while simultaneously measuring an internal angle of gyration.
7.1.1 Data Acquisition—The timing of the data acquisition system may be automatically triggered by the start of the gyration
process. Provision for excluding a known number of initial gyrations from the angle measurement may be provided (initial delay
period), and the angle shall be measured throughout a known number of subsequent gyrations (data acquisition period). The
durations of the initial delay and the data acquisition periods may be programmab
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