Designation:D3387−11
Standard Test Method for
Compaction and Shear Properties of Bituminous Mixtures by Means of the U.S.Corps of Engineers Gyratory Testing Machine(GTM)1
This standard is issued under thefixed designation D3387;the number immediately following the designation indicates the year of original adoption or,in the ca of revision,the year of last revision.A number in parenthes indicates the year of last reapproval.A superscript epsilon(´)indicates an editorial change since the last revision or reapproval.
1.Scope
1.1This method employs a testing machine(Fig.1)that generates a precily controlled gyratory kneading process which is ud to prepare and test specimens of bituminous paving mixtures.This method is intended for u in bituminous mixtures design and control testing as well as accelerated traffic simulation.The objective is to compact to the ultimate in place density under the anticipated vertical stress while moni-toring the process in terms of unit mass,and shearing resis-tance including the plastic properties.Particular attention is given to the development of the plastic properties associated with the compaction phenomenon.The maximum permissible bitumen content is indicated directly by thefirst evidence of a progressive increa in shear strain(as indicated by a progres-sive increa in the gyratory angle)accompanied by a progres-sive reduction in shear strength(as indicated by a progressive reduction in roller pressure.)The procedures described here are for mix design and plant control as well as accelerated traffic simulation.
1.2This test method covers two parate modes of opera-tion of the Gyratory Testing Machine(GTM),namely:(1) GTM oil-filled roller mode;and(2)GTM air-filled roller mode. With the airfilled roller,the GTM machine angle varies according to the resistance encountered during the gyratory kneading process.Thus the GTM using the air-filled roller is considered a better mechanical analog of the interaction between pneumatic tire and pavement structure.
1.3This test method is for u with mixtures containing asphalt cement,asphalt binder cutback asphalt,asphalt emul-sion.Test molds are available in4-in.(101.6mm),6-in.( 15
2.4mm),and8-in.(20
3.2mm)diameters with corresponding height of8-in(203.2mm),10-in.(25
4.0mm),and12-in.(304.8 mm)respectively.The molds can accommodate maximum particle sizes of1in.(2
5.4mm)1.5-in.(38.1mm)and2.0-in.
(50.8mm)respectively.
1.4Units—The values stated in inch pound units are to be regarded as standard.The values given in parenthes are mathematical conversions to SI units that are provided for information only and are not considered standard.
1.5The text of this standard references notes and footnotes which provide explanatory material.The notes and footnotes (excluding tho in tables andfigures)shall not be considered as requirements of the standard.
1.6This standard may involve hazardous materials, operations,and equipment.This standard does not purport to address all of the safety concerns,if any,associated with its u.It is the responsibility of the ur of this standard to establish appropriate safety and health practices and deter-mine the applicability of regulatory limitations prior to u.
2.Referenced Documents
2.1ASTM Standards:2
D3666Specification for Minimum Requirements for Agen-cies Testing and Inspecting Road and Paving Materials E1Specification for ASTM Liquid-in-Glass Thermometers 3.Terminology
3.1Definitions:田猜一成语
3.1.1Critical roller pressure,p’—the roller pressure re-quired for a Gyratory Shear Factor(GSF)equal to unity.That is,the roller pressure when SG=t max.(See Annex A1)
3.1.2Equilibrium density—density when a rate of densifi-cation of1lb/ft3(16kg/m3)per100revolutions of the GTM roller carriage is reached.This rate of densification is intended to duplicate the ultimate in place density.
3.1.3Gyratory Angle—measure of the magnitude of the gyratory strain u.Four pertinent angles are defined as follows: 3.1.3.1Machine angle(machine tting)u0.
1This test method is under the jurisdiction of ASTM Committee D04on Road and Paving Materials and is the direct responsibility of Subcommittee D04.26on
Fundamental/Mechanistic Tests.
Current edition approved Aug.1,2011.Published September2011.Originally approved in1974.Last previous edition approved in2003as D3387–03.DOI: 10.1520/D3387-11.
2For referenced ASTM standards,visit the ASTM website,www.astm,or contact ASTM Customer Service at rvice@astm.For Annual Book of ASTM Standards volume information,refer to the standard’s Document Summary page on the ASTM website.
Copyright©ASTM International,100Barr Harbor Drive,PO Box C700,West Conshohocken,PA19428-2959.United States
3.1.3.2Minimum gyratory angle or shear strain u min .3.1.3.3Maximum gyratory angle or shear strain u max .
做人的基本原则
3.1.3.4Final gyratory angle u f .This is the angle at the conclusion of
test.
FIG.1Largest Model of Gyratory Testing
Machine
3.1.4Gyratory Compactibility Index(GCI)—the ratio of the unit mass(total mix)at30revolutions of the GTM to the unit mass(total mix)at60revolutions of the GTM.
3.1.5Gyratory Compression Modulus(Eg)—a calculated value bad upon the gyratory shear modulus Gg and a measured or assumed value of Poissons´ratioµ.Eg=2Gg(1 +µ)
3.1.6Gyratory Shear Factor(GSF)—the ratio of the mea-sured gyratory shear strength to the theoretical maximum induced pavement shear stress;SG/t max.This is a factor of safety type index with regard to failure in simple shear for the defined loading conditions.The GSF value is not applicable when GSI>1.0
3.1.7Gyratory Shear Modulus(G g)—The gyratory shear SG divided by the gyratory shear strain tan u,(G g=S G/tan u0) 3.1.8Gyratory Shear Strength(S G)—the shear resistance of the specimen which is,among other things,a function of the impod vertical pressure and degree of strain.The S G value is influenced by the characteristics of the aggregate,binder and level of densification achieved.
蛔虫病的症状3.1.9Gyratory Stability Index(GSI)—the ratio of the maxi-mum gyratory angle to the minimum gyratory angle u max/u min.
4.Significance and U
4.1The GTM test method described here is intended to be ud to determine the maximum allowable bitumen content, establish unit mass requirements,and arrive at a rational shear strength.The GTM is also ud to conduct accelerated traffic simulation.It is esntial that the vertical pressure corresponds to the maximum anticipated vertical contact pressure between tire and pavement,since the theoretical stress for compaction and maximum induced shear is bad on the concept of employing maximum anticipated loads.
4.2The u of this methodfin the lection of the optimum bitumen content is limited to mixtures that are susceptible to the development of excess pore pressure when the voids become overfilled with b
itumen.This applies to den graded HMA but does not apply to SMA mixes or to open graded friction cours.(This restriction does not apply to the gyratory strength factor,GSF.)A gyratory stability index(GSI)in excess of unity,overfilled voids and therefore rves to establish the maximum permissible bitumen content.The optimum bitumen content should be lected at a value of GSI equals one.This is established by interpolation of a graph of GSI vs.bitumen content.An increa in this index indicates an excessive bitumen content for the compaction pressure employed and foretells instability of the bituminous mixture for the loading employed.A reduction in roller pressure during the compaction process likewi indicates loss of stability becau of overfilled voids;this phenomenon also rves as an indicator of maxi-mum allowable bitumen content as does the increa of gyratory angle which gives a stability index in excess of unity.
4.3It must be pointed out that the gyratory angle,being a measure of shear strain,is highly nsitive to temperature, especially on the rich side of optimum where the voids are overfilled and the shear stress is being transferred to the bituminous pha.Also,once the voids become over-filled,the bituminous mixture is subject to the phenomenon that may be best described as“stress-softening”,that isflattening of the stress-strain curve(reduction in stability)with continued kneading.Attempts to relate GSI values to performance is not recommended other than to identify the maximum permissible bitumen content as that at which the GSI value starts to exceed one.
N OTE1—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 ud. Agencies that meet the criteria of Standard Practice D3666are generally considered capable of competent and objective testing/sampling/ inspection/etc.Urs of this standard are cautioned that compliance with D3666alone does not completely assure reliable results.Reliable results depend on many factors;following the suggestions of D3666or some similar acceptable guideline provides a mean of evaluating and controlling some of tho factors.
5.Apparatus
5.1Gyratory Testing Machine(GTM)and Appurtenances—The primary equipment for this test is the Gyratory Testing Machine(GTM)and appurtenances.Fig.1is a photograph of the largest model GTM which is equipped to test4-in.(101.6 mm),6-in.(152.4mm),or8-in.(203.2mm)specimens.Refer to manufacturer’s manual for more information.
5.2Supplementary Equipment−the following conventional materials testing laboratory equipment will be required:
5.2.1Ovens—Ventilated ovens shall be provided for heating aggregates,bituminous material,and spe
cimen molds and for curing cut-back mixes and emulsion mixes.It is recommended that the heating units be thermostatically controlled so as to maintain the required temperature within5°F(2.8°C).
5.2.2Balances,one having a capacity of5kg or more, nsitive to1.0g and one having a capacity of2kg,nsitive to0.1g.
5.2.3Thermometers—Armored glass or dial-type thermom-eters with metal stems are recommended.A range from50to 400°F(9.9to20.4°C)with nsitivity of5°F(2.8°C)is required.
5.2.4Miscellaneous Apparatus—Trowels,spatulas,scoops, spoons,gloves,rubber gloves,metal pans.
6.Test Specimens
6.1Refer to manufacturer’s manual for detail information.
6.2Prepare at least three specimens for each combination of aggregate and bitumen.Include a range of bitumen contents so as to fully develop the compaction curve,develop a smooth curve of GSI vs.bitumen content and have at least three bitumen contents in which the gyratory angle shows progres-sive increa with continued compaction.Conduct check tests on outliers as necessary to insure smooth curves of density, GSI and gyratory shear vs.bitumen content
6.3Preparation of Aggregates—Separate the aggregate into the various size fractions necessary for accurately recombining into test mixtures conforming to specified grading require-
ments.
6.4Preparation of Mixtures—Combine the freeoven-dried aggregates into appropriate size batches.See 6.6for size of compacted specimens.Heat the aggregate to the desired temperature,into the aggregate mixture.Mixing of the aggre-gate and bitumen shallshould be as thorough and rapid as possible;mechanical mixing is recommended.
N OTE 2—For estimating purpos u 156.0pounds/cubic foot (2.5Mg/m 3)as the unit weight of compacted specimen.
6.5For mixes employing penetration/viscosity/PG grades of asphalt,the temperature of the aggregate and asphalt at the time of mixing should correspond to the temperatures antici-pated to be ud at the plant during manufacture of the
paving
FIG.2GTM Compaction and Shear
Test
员工调薪申请表mix.The temperatures will generally be somewhere in the range of250to325°F(121to163°C).
6.6For mixtures employing liquid bitumen(cutbacks or emulsions),the asphalt need not be heated but the aggregate should be dried to constant weight at221to230°F(105to 110°C).Cool the aggregate to room temperature and then mix with liquid bitumen.Following mixing,cure the loo mixture in a ventilated oven maintained at221to230°F(105to 110°C)for at least12hours prior to compaction at this temperature.The mix may be stirred occasionally during curing to accelerate loss of volatiles.
6.7Size of Specimens—The GTM can prepare a wide range of specimen lengths in the different diameter molds,including duplications of actual pavement thickness.It is recommended that for most
purpos,a ratio of1to1of diameter to height be ud so as to obtain the most favorable ratio of particle size to mold size for height as well as diameter.Recommended sizes are:
Mold Diameter Specimen Height
4to4.01inches(101.6to 101.9mm)3.5to4inches(88.9to101.6 mm)洛阳年票
6to6.01inches(152.4to 152.7mm)5.5to6inches(139.7to152.4 mm)
8to8.01inches(203.2to 203.5mm)7.5to8inches(190.5to203.2 mm)
N OTE3—Trial batches might be needed to verify the batch weights to obtain desired specimen heights.
7.Calibration and Standardization
7.1Refer to manufacturer’s manual for detail information.
8.Test Procedure
8.1Compaction and Shear Test
8.1.1Set the GTM heater control to the maximum antici-pated pavement temperature.Install the mold chuck front clamp piece and turn the heater on.Allow sufficient time for the heater indicator light to show that the temperature has been attained by lighting up intermittently(approximately1hour is required).
8.1.2Prepare three initial batches of mix at each of the following suggested bitumen contents:(1)At the estimated optimum bitumen content(2)0.5%less than estimated opti-mum(3)0.5%greater than estimated optimum.Conduct additional tests and check tests for outliers as required ensuring fully developed smooth curves of density,GSI and gyratory shear vs.bitumen content.Include at least three specimens for which GSI exceeds one.
8.1.3Test parameters to be checked,input,or recorded include the following:
8.1.3.1Material Type–bituminous mix
8.1.3.2Location where test material will be in pavement structure−surface/subsurface including thickness of cover layers
8.1.3.3Contact Pressure−to be estimated from anticipated maximum tire pavement contact pressure as pavement design criteria
8.1.3.4Vertical Pressure–the program calculates and dis-plays the needed vertical pressure bad on the design contact pressure,thickness of cover layers and type of materials input by the operator
8.1.3.5Quantity of Material
8.1.3.6Percent bitumen
8.1.3.7Specimen Description
8.1.3.8Test Termination Condition(Equilibrium Density, Specimen Height,Density or Number of Revolutions) N OTE4—New GTM program allows the ur four different options for controlling the end-point of the compaction process.Refer to manufac-turer’s manual for more information
8.1.4Set Vertical Pressure which the specimen will be subjected to under design contact pressure during u.Sub-surface material will obviously experience lower stress than surface material.
8.1.5When using an oil-filled roller t a machine angle of 0.8˚
8.1.6When using an airfilled roller t an initial machine angle of2˚with a high pressure(>1.5x p’)in the roller cylinder to preclude compression of the roller during the angle tting procedure.After the i
nitial machine angle is t at2˚reduce the air pressure in the roller cylinder to the critical pressure p’corresponding to the size specimen.(See Annex A and defini-tion for p’)
8.1.7Prepare a moldfilled with the test mix and heated within2.8°C of the anticipated plant mix temperature.Install the mold in the GTM.Start compaction test andof the shear mix.
8.1.8During compaction the computer will record all mea-sured parameters as follows in each revolution:
8.1.8.1Revolution number
8.1.8.2Specimen height
8.1.8.3Specimen density同安六中
8.1.8.4Gyratory angle
8.1.8.5Work done(energy provided)
Program then make tho calculations necessary to deter-mine if the lected termination condition
has been met.The GTM will compact the mix until the lected termination condition is reached,at which point the computer will stop the roller carriage.There is no need to stop the carriage during the test at any point.
N OTE5—This applies to computerized models only.For non-computerized models,refer to manufacturer’s manual.
8.1.9Upon completion of compaction,allow the mold chuck temperature to stabilize at the maximum anticipated pavement temperature before taking thefinal readings.
8.2Cyclic Loading Test
8.2.1When the compaction test has been completed the GTM software includes an optional test that can be run on the new computerized GTM.This is the cyclic loading test which measures the dynamic compression and rebound moduli of the test specimen.This test is conducted on a specimen immedi-ately after a compaction test has been run.The cyclic loading test option can be lected at the end of a compaction and shear test.Clicking on the cyclic loading option button will start the cyclic loading program The cyclic loading program
quences
the vertical pressure applied to the specimen while the speci-men is also undergoing gyratory kneading.
8.2.2The cyclic loading program will t up a screen graph to give an analog display of the applied pressure cycle and the resulting specimen deflection.This graphical display is linear in both the vertical axis and the horizontal axis.The horizontal axis for this graph is time,not revolutions as was the ca for the compaction test.
8.2.3The program will store measurements of specimen deflection and cyclic pressure change for11revolutions,then stop the roller carriage,compute all dynamic parameters and print out the result.
8.3Wall Friction Test
指甲上的月牙
8.3.1When the GTM compaction and shear test have been completed there is an optional test that can be performed to give an improved accuracy to the test results;this is the wall friction test.This test must be performed immediately after the compaction and shear test have been completed.If a wall friction test is planned,click on the wall friction test option on the computerized GTM or follow the manufacturer’s directions for the noncomputerized model to obtain the wall friction data. Enter the measured wall friction data into the computer or on the data sheet.This correction for wall friction is then ud in subquent calculations.
8.3.2Click on the text box associated with the wall friction option and enter the wall friction pressure reading noted above. Then click the next button.The computer will then print the test results using the wall friction data entry.
8.3.3When a wall friction entry is made the computer printout for the compaction test will include a ction for results that include corrections for wall friction in the compu-tations as well as the standard computations.
9.Calculation or Interpretation of Results
9.1After specimen compaction is terminated the computer will u the measurements collected to ca
lculate results and print a report(no manual calculation is needed).The following are the main calculated results:
9.1.1Unit Weight at the end of compaction
9.1.2Gyratory Compatibility Index(GCI)
N OTE6—With newer models of GTM,recommending using Total Work Done(Total Energy Provided)instead of GCI.
9.1.3Total Work Done(Total Energy Provided)
9.1.4Gyratory Stability Index(GSI)
9.1.5Gyratory Shear Factor(GSF)
9.1.6Static Shear Modulus
9.1.7Static Compression Modulus
9.1.8Dynamic Shear Modulus(if cyclic loading test is chon at the end of compaction test)
节制闸9.1.9Dynamic Compression Modulus(if cyclic loading test is chon at the end of compaction test)
9.2All of the information collected during each test is stored in afile on the computer disk drive.
9.3Test results can be retrieved at a later date and a report duplicating the end-of-test report can be printed.
9.4The test-results-file can also be retrieved into an Excel spreadsheet for other study if desired.10.Report
10.1The following are various items to be reported along with the test report:
10.1.1Date and time
10.1.2Test Number
10.1.3Name of operator
10.1.4Total Specimen Weight
10.1.5Percent of Bitumen
10.1.6Compaction Stress
10.1.7Number of Revolution at the end of compaction 10.1.8Compaction Terminated Condition
10.1.9Specimen Height at End of Compaction
10.1.10Unit Weight of Total Mix
10.1.11Unit Weight of Aggregate only.
10.1.12Ud of O-rings or not
10.1.13Gyratory Compatibility Index
10.1.14Total Work Done
10.1.15Machine Angle
10.1.16Intermediate Gyratory Angle
10.1.17Gyratory Angle at the end of Compaction
10.1.18Gyratory Stability Index
10.1.19Average Roller Pressure
10.1.20Static Shear Strength
10.1.21Gyratory Shear Factor
10.1.22Static Shear Modulus
10.1.23Static Compression Modulus
10.1.24Dynamic Shear Modulus(if cyclic loading test is chon at the end of compaction test)
10.1.25Dynamic Compression Modulus(if cyclic loading test is chon at the end of compaction test)
10.2In addition to the parameters in10.1,the report shall include the following parameters for each specimen tested using the oilfilled roller mode of operation:
10.2.1Gyratory shear strength(S G),and
10.2.2Gyratory strength factor(GSF).
10.3An example of a test report(retrieved from testfile)is provided in the11.1.The test report includes specimen identification,tup parameters and calculated results.The test report also includes a graph of the measurements recorded each revolution.
11.Precision and Bias
11.1The within-laboratory repeatability standard deviation for gyratory stability index(GSI)has been determined to be 0.007,bad on one lab,4test replicates,and16different samples.The within-laboratory repeatability standard devia-tion for Density has been determined to be0.044gm/cc,bad on one lab,4test replicates,and16different samples The betweenlaboratory reproducibility of this test method is being determined and will be available on or before June2016. Therefore,this Standard should not be ud for acceptance or rejection of a material for purchasing purpos
11.2Bias—since there is no accepted reference material suitable for determining the bias for the procedure in the test methods for measuring the GSI and density,no statement on bias is being
made.
