ASTM D7115-05
(Test Method)Standard Test Method for Measurement of Superpave Gyratory Compactor (SGC) Internal Angle of Gyration Using Simulated Loading
Standard Test Method for Measurement of Superpave Gyratory Compactor (SGC) Internal Angle of Gyration Using Simulated Loading
SIGNIFICANCE AND USE
SGCs are used to produce hot-mix asphalt (HMA) specimens in the laboratory to assess volumetric properties and predict pavement performance. In the fabrication of an SGC specimen in accordance with Test Method D 6925, loose HMA 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 angle of gyration) and rate. Consistency in the density of the asphalt specimens produced as measured by Test Method D 2726 or D 6752 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 angle of gyration during the compaction process.
There are several manufacturers and models of SGC. Each model employs a unique method of setting, inducing, and maintaining the angle of gyration. Each model also employs a unique calibration system to measure the external angle of gyration. These existing calibration systems can not 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.
This method describes instruments and processes that can be used to independently measure the internal angle of gyration of any manufacturers’ SGC model under simulated loading conditions. The external shape of the instrument chassis assures 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.
Unless otherwise specified, tilting moments corresponding to an eccentricity of 22 mm shall be used to simulate the loading conditions of a standard SGC volumetric specimen.
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 specimen.
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:D7115–05
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 D 7115; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3.1.3 top internal angle—the angle formed between the
internal mold diameter and the upper mold end plate as a mold
1.1 This test method covers the procedure for the measure-
is gyrated in a Superpave Gyratory Compactor.
ment of the Superpave Gyratory Compactor (SGC) internal
3.1.4 bottom internal angle—the angle formed between the
angle of gyration using an instrument capable of simulating
internal mold diameter and the lower mold end plate as a mold
loadingconditionssimilartothosecreatedbyahotmixasphalt
is gyrated in a Superpave Gyratory Compactor.
specimen.
3.1.5 effective internal angle—the average of the top inter-
1.2 This standard does not purport to address all of the
nal angle and the bottom internal angle.
safety concerns, if any, associated with its use. It is the
3.1.6 tilting moment—a force (F) acting at one end of an
responsibility of the user of this standard to establish appro-
SGC mold platen in a direction parallel to the axis of gyration,
priate safety and health practices and determine the applica-
but acting at some distance (e) away from that axis. The tilting
bility of regulatory limitations prior to use.
moment at one end of the mold platen is computed as the
2. Referenced Documents
product of this distance (e) and force (F).
3.1.7 total moment—thesumtotal(M)ofthetiltingmoment
2.1 ASTM Standards:
acting at the top of the mold and the tilting moment acting at
D 2726 Test Method for Bulk Specific Gravity and Density
the bottom of the mold.
of Non-Absorptive Compacted Bituminous Materials
3.1.8 eccentricity—the distance (e) away from the axis of
D 6752 Test Method for Bulk Specific Gravity and Density
gyration at which a force (F) is acting at one end of an SGC
of Compacted Bituminous Mixtures Using Automatic
mold. This use of the term eccentricity is consistent with
Vacuum Sealing Method
previous published reports describing the mechanics of gyra-
D 6925 Test Method for the Preparation and Determination
tory compaction.
of the Relative Density of Hot Mix Asphalt (HMA)
3.1.9 standard SGC volumetric specimen—a standard sized
Specimens by Means of the Superpave Gyratory Compac-
hot mix asphalt specimen prepared using an SGC for purposes
tor
of volumetric mix design. Such a standard specimen, prepared
E 691 Practice for Conducting an Inter-laboratory Study to
in accordance with Test Method D 6925, has a diameter of 150
Determine the Precision of a Test Method
mm and a final compacted height of 115 6 5 mm.
3. Terminology
4. Summary of Test Method
3.1 Definitions:
4.1 The internal angle of gyration of an SGC is measured
3.1.1 external angle—the angle formed between the exter-
dynamically with an instrument inserted into the SGC mold.
nal mold diameter and a stationary reference axis of the
4.2 A load (moment) is induced on the SGC while the
machine frame.
internal angle is simultaneously measured. The simulated
3.1.2 internal angle—the angle formed between the internal
loading conditions are similar to those created by compaction
mold diameter and a mold end plate as a mold is gyrated in a
of a standard SGC volumetric specimen.
Superpave Gyratory Compactor.
4.3 The internal angles at each end of the mold are mea-
suredandthenaveragedtoobtaintheeffectiveinternalangleof
This test method is under the jurisdiction of ASTM Committee D04 on Road
gyration.
and Paving Materials and is the direct responsibility of Subcommittee D04.20 on
Mechanical Tests of Bituminous Mixtures.
Current edition approved Feb. 1, 2005. Published February 2005.
2 3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Guler, M., Bahia, H. U., Bosscher, P. J., and Plesha, M. E., “Device for
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Measuring Shear Resistance of Hot Mix Asphalt in Gyratory Compactor,” Trans-
Standards volume information, refer to the standard’s Document Summary page on portation Research Record 1723,TRB,NationalAcademyofSciences,Washington,
the ASTM website. DC, 2000, pp. 116-124.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D7115–05
5. Significance and Use initial gyrations from the angle measurement may be provided
(initial delay period), and the angle shall be measured through-
5.1 SGCs are used to produce hot-mix asphalt (HMA)
out a known number of subsequent gyrations (data acquisition
specimens in the laboratory to assess volumetric properties and
period). The durations of the initial delay and the data
predict pavement performance. In the fabrication of an SGC
acquisition periods may be programmable or fixed.
specimen in accordance withTest Method D 6925, loose HMA
7.1.2 Display Options—The angle measurement result(s)
is placed inside a metal mold, which is then placed into an
may be viewable on a display built into the instrument chassis
SGC. A constant consolidation pressure is applied to the
and/or retrievable from the instrument via a communications
sample while the mold gyrates at a nominally constant angle
port.
(referred to as the angle of gyration) and rate. Consistency in
7.1.3 Temperature Measurement—The instrument may op-
the density of the asphalt specimens produced as measured by
tionally have a means for displaying, recording or otherwise
TestMethodD 2726orD 6752isveryimportanttothevalidity
indicating its internal temperature during the angle measure-
of the tests performed. Specimens of a consistent density are
ment process.
produced when an SGC maintains a constant pressure and a
7.1.4 Static Angle Gage—A NIST-traceable angle gage
known constant angle of gyration during the compaction
device with one or more known angles used to calibrate and to
process.
verify the calibration of the angle measurement instrument.
5.2 There are several manufacturers and models of SGC.
7.1.5 Wear Protection Plates—Thin steel plates (optional)
Each model employs a unique method of setting, inducing, and
which protect the SGC mold end plates from any cosmetic
maintaining the angle of gyration. Each model also employs a
damage by the contact rings.
unique calibration system to measure the external angle of
7.2 Superpave Gyratory Compactor (SGC) and associated
gyration. These existing calibration systems can not be used
equipment as described inTest Method D 6925.The SGC shall
universally on all of the different SGC models commercially
be in good repair with the compaction pressure, specimen
available. Inconsistencies in asphalt specimens produced on
height measurement system, and gyration rate verified to be
different SGC models have been at least partially attributed to
within specifications. The mechanisms used to induce and
variations in the angle of gyration.
maintain the angle of gyration shall be set and maintained
5.3 This method describes instruments and processes that
within the manufacturer’s guidelines.
can be used to independently measure the internal angle of
7.2.1 The SGC molds, mold end plates, base platens, and
gyration of any manufacturers’ SGC model under simulated
ram head surface smoothness shall be confirmed to be within
loading conditions. The external shape of the instrument
the specifications of Test Method D 6925. Any equipment not
chassis assures that the points of physical contact between the
meeting these requirements shall not be used.
mold end plates and the instrument occur at a fixed and known
distanceawayfromtheaxisofgyration.Asaresult,thevertical
8. Preparation of Apparatus
load is applied at these fixed points, creating tilting moments at
8.1 Before each use of the angle measurement instrument,
each end of the mold.
verify the angle measurement system using the static angle
5.4 Unless otherwise specified, tilting moments correspond-
gage according to manufacturer’s instructions. The static angle
ing to an eccentricity of 22 mm shall be used to simulate the
gage, which can apply one or more known angles to the
loading conditions of a standard SGC volumetric specimen.
instrument, is used to confirm that the instrument is operating
within calibration. The instrument and the static angle gage
6. Interferences
must be at the same, uniform, stable temperature for the
6.1 DebrisontheSGCmold,baseplates,ramhead,reaction
verification to be accurate.
surfaces, or on the instrument can cause errant measurement
results. Extreme care should be taken to thoroughly clean the NOTE 1—These instruments typically have an operating temperature
range of 20 to 40°C. Consult the manufacturer’s instructions for specific
SGC, mold, instrument, and any work areas that will be
temperature limitations during calibration, verification, and use within the
utilized during the measurement procedure.
SGC.
6.2 Scarring or irregular surfaces on mold walls and end
plates is also known to cause incorrect results. Do not use any 8.2 Be sure the probe tips and contact rings on the angle
measurement instrument are free of debris.
equipment that shows signs of damage. The precision required
in the execution of this test method necessitates that extreme 8.3 Prepare a clean compaction mold assembly.
caremustbetakentoavoiderrorsfromdamagedorimproperly
NOTE 2—Accumulation of HMA on mold surfaces, mold end plates,
maintained equipment.
base platens, and/or ram hea
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