1、Designation: D 7115 08Standard Test Method forMeasurement of Superpave Gyratory Compactor (SGC)Internal Angle of Gyration Using Simulated Loading1This standard is issued under the fixed designation D 7115; the number immediately following the designation indicates the year oforiginal adoption or, in
2、 the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the procedure for the measure-ment of the Superpave Gyrator
3、y Compactor (SGC) internalangle of gyration using an instrument capable of simulatingloading conditions similar to those created by a hot mix asphaltspecimen.1.2 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user
4、of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C 670 Practice for Preparing Precision and Bias Statementsfor Test Methods for Construction MaterialsD 2726 Test M
5、ethod for Bulk Specific Gravity and Densityof Non-Absorptive Compacted Bituminous MixturesD 3666 Specification for Minimum Requirements forAgen-cies Testing and Inspecting Road and Paving MaterialsD 6752 Test Method for Bulk Specific Gravity and Densityof Compacted Bituminous Mixtures Using Automati
6、cVacuum Sealing MethodD 6925 Test Method for Preparation and Determination ofthe Relative Density of Hot Mix Asphalt (HMA) Speci-mens by Means of the Superpave Gyratory CompactorE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 Definit
7、ions:3.1.1 external anglethe angle formed between the exter-nal mold diameter and a stationary reference axis of themachine frame.3.1.2 internal anglethe angle formed between the internalmold diameter and a mold end plate as a mold is gyrated in anSGC.3.1.3 top internal anglethe angle formed between
8、 theinternal mold diameter and the upper mold end plate as a moldis gyrated in an SGC.3.1.4 bottom internal anglethe angle formed between theinternal mold diameter and the lower mold end plate as a moldis gyrated in an SGC.3.1.5 effective internal anglethe average of the top inter-nal angle and the
9、bottom internal angle.3.1.6 tilting momenta force (F) acting at one end of anSGC mold platen in a direction parallel to the axis of gyration,but acting at some distance (e) away from that axis. The tiltingmoment at one end of the mold platen is computed as theproduct of this distance (e) and force (
10、F).3.1.7 total momentthe sum total (M) of the tilting momentacting at the top of the mold and the tilting moment acting atthe bottom of the mold.3.1.8 eccentricitythe distance (e) away from the axis ofgyration at which a force (F) is acting at one end of an SGCmold. This use of the term eccentricity
11、 is consistent withprevious published reports describing the mechanics of gyra-tory compaction.33.1.9 standard SGC volumetric specimena standard sizedhot mix asphalt specimen prepared using an SGC for purposesof volumetric mix design. Such a standard specimen, preparedin accordance with Test Method
12、D 6925, has a diameter of 150mm and a final compacted height of 115 6 5 mm.4. Summary of Test Method4.1 The internal angle of gyration of an SGC is measureddynamically with an instrument inserted into the SGC mold.1This test method is under the jurisdiction of ASTM Committee D04 on Roadand Paving Ma
13、terials and is the direct responsibility of Subcommittee D04.20 onMechanical Tests of Bituminous Mixtures.Current edition approved July 1, 2008. Published July 2008. Originally approvedin 2005. Last previous edition approved in 2005 as D 7115 05.2For referenced ASTM standards, visit the ASTM website
14、, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Guler, M., Bahia, H. U., Bosscher, P. J., and Plesha, M. E., “Device forMeasuring Shear Resistance of Hot Mix Asph
15、alt in Gyratory Compactor,” Trans-portation Research Record 1723, TRB, NationalAcademy of Sciences, Washington,DC, 2000, pp. 116124.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.2 A load (moment) is induced on the SGC while thein
16、ternal angle is simultaneously measured. The simulatedloading conditions are similar to those created by compactionof a standard SGC volumetric specimen.4.3 The internal angles at each end of the mold are mea-sured and then averaged to obtain the effective internal angle ofgyration.5. Significance a
17、nd Use5.1 SGCs are used to produce hot-mix asphalt (HMA)specimens in the laboratory to assess volumetric properties andpredict pavement performance. In the fabrication of an SGCspecimen in accordance with Test Method D 6925, loose HMAis placed inside a metal mold, which is then placed into anSGC. A
18、constant consolidation pressure is applied to thesample while the mold gyrates at a nominally constant angle(referred to as the angle of gyration) and rate. Consistency inthe density of the asphalt specimens produced as measured byTest Methods D 2726 or D 6752 is very important to thevalidity of the
19、 tests performed. Specimens of a consistentdensity are produced when an SGC maintains a constantpressure and a known constant angle of gyration during thecompaction process.5.2 There are several manufacturers and models of SGC.Each model employs a unique method of setting, inducing, andmaintaining t
20、he angle of gyration. Each model also employs aunique calibration system to measure the external angle ofgyration. These existing calibration systems can not be useduniversally on all of the different SGC models commerciallyavailable. Inconsistencies in asphalt specimens produced ondifferent SGC mod
21、els have been at least partially attributed tovariations in the angle of gyration.5.3 This method describes instruments and processes thatcan be used to independently measure the internal angle ofgyration of any manufacturers SGC model under simulatedloading conditions. The external shape of the ins
22、trumentchassis assures that the points of physical contact between themold end plates and the instrument occur at a fixed and knowndistance away from the axis of gyration.As a result, the verticalload is applied at these fixed points, creating tilting moments ateach end of the mold.5.4 Unless otherw
23、ise specified, a tilting moment of 466.5N-m shall be applied to the SGC by the instrument whilemaking this measurement.NOTE 1The quality of the results produced by this test method aredependent on the competence of the personnel performing the procedureand the capability, calibration, and maintenanc
24、e of the equipment used.Agencies that meet the criteria of Practice D 3666 are generally consid-ered capable of competent and objective testing/sampling/inspection/etc.Users of this test method are cautioned that compliance with PracticeD 3666 alone does not completely assure reliable results. Relia
25、ble resultsdepend on many factors; following the suggestions of Practice D 3666 orsome similar acceptable guideline provides a means of evaluating andcontrolling some of those factors.NOTE 2A 466.5 N-m tilting moment corresponds to a 22 mmeccentric on the AFLS1 or a 21 deg cone angle on the DAVII-HM
26、S withan applied load of 10603 N (600 kPa at a 150 mm diameter specimensetting).6. Interferences6.1 Debris on the SGC mold, base plates, ram head, reactionsurfaces, or instrument can cause errant measurement results.Extreme care should be taken to thoroughly clean the SGC,mold, instrument, and any w
27、ork areas that will be utilizedduring the measurement procedure.6.2 Scarring or irregular surfaces on mold walls and endplates is also known to cause incorrect results. Do not use anyequipment that shows signs of damage. The precision requiredin the execution of this test method necessitates that ex
28、tremecare must be taken to avoid errors from damaged or improperlymaintained equipment.7. Apparatus7.1 An instrument capable of being gyrated inside an SGCmold which induces tilting moments at each end of the SGCmold while simultaneously measuring an internal angle ofgyration.7.1.1 Data AcquisitionT
29、he timing of the data acquisitionsystem may be automatically triggered by the start of thegyration process. Provision for excluding a known number ofinitial gyrations from the angle measurement may be provided(initial delay period), and the angle shall be measured through-out a known number of subse
30、quent gyrations (data acquisitionperiod). The durations of the initial delay and the dataacquisition periods may be programmable or fixed.7.1.2 Display OptionsThe angle measurement result(s)may be viewable on a display built into the instrument chassisor retrievable from the instrument by means of a
31、 communica-tions port, or both.7.1.3 Temperature MeasurementThe instrument may op-tionally have a means for displaying, recording, or otherwiseindicating its internal temperature during the angle measure-ment process.7.1.4 Static Angle GageA National Institute of Standardsand Technology (NIST)-trace
32、able angle gage device with oneor more known angles used to calibrate and to verify thecalibration of the angle measurement instrument.7.1.5 Wear Protection PlatesThin steel plates (optional)which protect the SGC mold end plates from any cosmeticdamage by the contact rings.7.2 Superpave Gyratory Com
33、pactor (SGC) and associatedequipment as described in Test Method D 6925. The SGC shallbe in good repair with the compaction pressure, specimenheight measurement system, and gyration rate verified to bewithin specifications. The mechanisms used to induce andmaintain the angle of gyration shall be set
34、 and maintainedwithin the manufacturers guidelines.7.2.1 The SGC molds, mold end plates, base platens, andram head surface smoothness shall be confirmed to be withinthe specifications of Test Method D 6925. Any equipment notmeeting these requirements shall not be used.8. Preparation of Apparatus8.1
35、Before each use of the angle measurement instrument,verify the angle measurement system using the static anglegage according to manufacturers instructions. The static anglegage, which can apply one or more known angles to theD7115082instrument, is used to confirm that the instrument is operatingwith
36、in calibration. The instrument and the static angle gagemust be at the same, uniform, stable temperature for theverification to be accurate.NOTE 3These instruments typically have an operating temperaturerange of 20 to 40C. Consult the manufacturers instructions for specifictemperature limitations du
37、ring calibration, verification, and use within theSGC.8.2 Be sure the probe tips and contact rings on the anglemeasurement instrument are free of debris.8.3 Prepare a clean compaction mold assembly.NOTE 4Accumulation of HMA on mold surfaces, mold end plates,base platens, or ram head surfaces, or com
38、bination thereof, directlyimpacts the instruments ability to accurately measure the angle ofgyration. Use mineral spirits or another appropriate solvent to clean thesesurfaces.8.4 Perform the angle measurement with the SGC mold atroom temperature. Optionally, the measurement may be madewith the mold
39、 at an elevated temperature. If the angle mea-surement is to be made at an elevated temperature, then placethe SGC mold in an oven at the desired temperature 6 5C fora minimum of 45 min prior to making the first angle measure-ment. Do not place the angle measurement instrument in theoven. Mold tempe
40、ratures other than room temperature usedduring angle measurement shall be noted on the report.NOTE 5The SGC manufacturer may recommend measurement of theangle at an elevated temperature for those SGC models where the anglechanges with mold temperature.NOTE 6These instruments typically have an operat
41、ing temperaturerange of 20 to 40C. After use in a hot mold, the angle measurementinstrument can be cooled by using a fan to blow ambient air over theinstrument or by placing it in front of an air conditioner. Elevating theinstrument above the table surface so as to permit maximum airflow overthe ent
42、ire instrument will increase the rate of cooling. Do not cool theinstrument below room temperature. Consult the manufacturers instruc-tions for specific temperature limitations during calibration, verification,and use within the SGC.8.5 Verify the settings on the compactor. Unless notedotherwise, th
43、e SGC shall be initialized to provide specimencompaction using a consolidation pressure of 600 6 18 kPa,and the gyration rate shall be 30 6 0.5 rpm.8.6 Set the number of gyrations on the SGC in accordancewith the recommendations of the manufacturer of the anglemeasurement instrument. Typically, ten
44、gyrations are sufficientto obtain an accurate angle measurement using simulatedloading.9. Calibration and Standardization9.1 The angle measurement instrument requires periodicstandardization. The system shall be standardized prior toinitial use and at least once every 12 months thereafter. Thisannua
45、l standardization shall follow instrument manufacturerrecommendations and include the following:9.1.1 Standardization of the static angle gage with a NISTtraceable measurement system, and9.1.2 Standardization of the angle measurement instrument.10. Procedure10.1 The average internal angle is based o
46、n six individualangle measurements as follows:10.1.1 The top internal angle is measured in triplicate.10.1.2 The bottom internal angle is measured in triplicate.10.2 Each of the six individual angle measurements isperformed as follows:10.2.1 Arm the angle measurement instrument for collect-ing data.
47、10.2.2 Place the angle measurement instrument inside theSGC mold. Orient the instrument probes or reference base asappropriate to measure the top or bottom angle.NOTE 7The operator may wish to use a specimen extruder to elevatethe bottom mold plate to a position where insertion of the anglemeasureme
48、nt instrument into the SGC mold is easier.10.2.3 Place the SGC mold inside the SGC.NOTE 8For some SGCs, it may be more convenient to first place themold in the SGC, and then place the angle measurement instrument in themold.10.2.4 Initiate the compaction process. For most SGCs, thisis an automatic p
49、rocess consisting of pressing a button to startthe compaction process. The SGC automatically applies theram pressure, induces the angle, and gyrates the mold to thespecified number of gyrations.10.2.5 Remove the angle measurement instrument from theSGC mold.NOTE 9Use caution when removing the instrument, especially whenusing a power extruder. Take care that the instrument does not get caughtor damaged during the extrusion process.10.2.6 Record the angle result reported by the instrument tonearest 0.01. Record which angle (top or bottom) and whichtrip
