1、Designation: D6926 16Standard Practice forPreparation of Asphalt Mixture Specimens Using MarshallApparatus1This standard is issued under the fixed designation D6926; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
2、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 practice covers preparation and compaction of 4 in.(101.6 mm) diameter by nominal 2.5 in. (63.5 mm) highcylindrical as
3、phalt paving mixture specimens. This practice isintended for use with laboratory and plant-produced asphaltmixtures with aggregate up to 1 in. (25.4 mm) maximum sizeand for recompaction of asphalt paving mixture samples.1.2 There are three types of Marshall compaction apparatusin use. The following
4、types of hammer arrangements areincluded in this practice:1.2.1 Manually held hammer handle is attached to a flatcompaction foot through a spring-loaded swivel and is handoperated (original standard developed by the United StatesArmy Corps of Engineers).1.2.2 Hammer handle restrained laterally (fixe
5、d) but notvertically, attached to a flat compaction foot through a spring-loaded swivel and is either mechanically or hand operated.There may or may not be a constant surcharge on top of thehammer handle. Mechanical hammers are available that oper-ate at (1) nominal 55 blows per minute or (2) equal
6、to or greaterthan 75 blows per minute.1.2.3 Hammer handle restrained laterally (fixed) with con-stant surcharge on top of hammer, is attached to a slantedcompaction foot on a rotating mold base, and is mechanicallyoperated. This method must be used as a referee method.1.3 Although the mass and heigh
7、t of mass drop for eachapparatus are the same, density achieved in compacted speci-mens with the same number of blows will be different. It is upto the owner or specifier to establish the specific requirednumber of blows to be used for compaction of the specimen inrelation to the field.1.4 UnitsThe
8、values stated in inch-pound units are to beregarded as standard. The values given in parentheses aremathematical conversions to SI units that are provided forinformation only and are not considered standard.1.5 The text of this standard references notes and footnoteswhich provide explanatory materia
9、l. These notes and footnotes(excluding those in tables and figures) shall not be consideredas requirements of the standard.2. Referenced Documents2.1 ASTM Standards:2D8 Terminology Relating to Materials for Roads and Pave-mentsD3666 Specification for Minimum Requirements for Agen-cies Testing and In
10、specting Road and Paving MaterialsD4402 Test Method for Viscosity Determination of Asphaltat Elevated Temperatures Using a Rotational ViscometerD6927 Test Method for Marshall Stability and Flow ofAsphalt MixturesE1 Specification for ASTM Liquid-in-Glass ThermometersE11 Specification for Woven Wire T
11、est Sieve Cloth and TestSievesE77 Test Method for Inspection and Verification of Ther-mometersE2251 Specification for Liquid-in-Glass ASTM Thermom-eters with Low-Hazard Precision Liquids3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this practice, refer toTerminology D8.3.2 Def
12、initions of Terms Specific to This Standard:3.2.1 lab mix lab compacted (LMLC) asphalt mixture,nasphalt mix samples that are prepared in the laboratory byweighing and blending each constituent then compacting theblended mixture after two hours of curing at the compactiontemperature or curing time sp
13、ecified by the owner, using alaboratory compaction apparatus.3.2.1.1 DiscussionLMLC typically occurs during the as-phalt mixture design phase.1This practice is under the jurisdiction of ASTM Committee D04 on Road andPaving Materials and is the direct responsibility of Subcommittee D04.20 onMechanica
14、l Tests of Asphalt Mixtures.Current edition approved Dec. 15, 2016. Published January 2017. Originallyapproved in 2004. Last previous edition approved in 2010 as D6926 10. DOI:10.1520/D6926-16.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at se
15、rviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance
16、 with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.13.2.2 plant mix laboratory compacted
17、(PMLC) asphaltmisture, nasphalt mix samples that are manufactured in aproduction plant, sampled prior to compaction, then immedi-ately compacted using a laboratory compaction apparatus.3.2.2.1 DiscussionPMLC specimens are often used forquality control testing. This designation is limited to specimen
18、sthat have not been permitted to cool substantially, but PMLCsamples may be placed in a laboratory oven to equilibrate themix to the compaction temperature before molding.3.2.3 reheated plant mix lab compacted (RPMLC) asphaltmixture, nasphalt mix samples that are manufactured in aproduction plant, s
19、ampled prior to compaction, allowed to coolto room temperature, then reheated in a laboratory oven andcompacted using a laboratory compaction apparatus.3.2.3.1 DiscussionRPMLCs are often used for qualityacceptance and verification testing. The reheating is as brief aspossible to obtain uniform tempe
20、rature while avoiding artificialaging of the specimens. Asphalt mix conditioning, reheattemperature, and reheat time should be defined in the appli-cable specification.4. Significance and Use4.1 Compacted asphalt mixture specimens molded by thisprocedure are used for various physical tests such as s
21、tability,flow, indirect tensile strength, fatigue, creep, and modulus.Density and void analysis are also conducted on specimens formixture design and evaluation of field compaction.NOTE 1Uncompacted mixtures are used for determination of theo-retical maximum specific gravity.NOTE 2The quality of the
22、 results produced by this practice aredependent on the competence of the personnel performing the procedureand the capability, calibration, and maintenance of the equipment used.Agencies that meet the criteria of Specification D3666 are generallyconsidered capable of competent and objective testing,
23、 sampling,inspection, etc. Users of this practice are cautioned that compliance withSpecification D3666 alone does not completely ensure reliable results.Reliable results depend on many factors; following the suggestions ofSpecification D3666 or some similar acceptable guideline provides ameans of e
24、valuating and controlling some of those factors.5. Apparatus5.1 Specimen Mold AssemblyMold cylinders, base plates,and extension collars shall conform to the details shown in Fig.1 (Compaction Mold).5.2 Specimen ExtractorThe specimen extractor shall havea steel disk that will enter the mold without b
25、inding and not beless than 3.95 in. (100.3 mm) in diameter and 0.5 in. (12.7 mm)thick. The steel disk is used for extracting compacted speci-mens from molds with the use of the mold collar. Any suitableextraction device such as a hydraulic jack apparatus or a leverarm device may be used, provided th
26、e specimens are notdeformed during the extraction process.5.3 Compaction Hammers:5.3.1 Compaction Hammers with a Manually Held (Type 1)or Fixed (Type 2) Handle, either mechanically or hand operatedas generally shown in Figs. 2 and 3, shall have a flat, circularcompaction foot with spring-loaded swiv
27、el and a 10 6 0.02 lb(4.545 6 0.009 kg) sliding mass with a free fall of 18 60.06 in. (457.2 6 1.5 mm) (see Fig. 2 for hammer tolerances).A typical manual compaction hammer is shown in Fig. 2.Atypical mechanical hammer is showed in Fig. 3.NOTE 3Manual compaction hammers should be equipped with afing
28、er safety guard.5.3.2 Compaction Hammers with a Fixed Hammer Handle,surcharge on top of handle, constantly rotating base, andmechanically operated (Type 3), shall have a slanted, circulartamping face and a 10 6 0.02 lb (4.536 6 0.009 kg) slidingweight with a free fall of 18 6 0.06 in. (457.2 6 1.5 m
29、m). SeeFig. 4 (Hammer Bevel Detail) for hammer and tamping facebevel angle and tolerances, respectively. A rotating mechanismis incorporated in the base. The base rotation rate and hammerblow rate shall be 18 to 30 rpm and 64 6 4 blows per minute,respectively.NOTE 4Multiple hammer operation may affe
30、ct the density of thesamples.5.4 Compaction PedestalThe compaction pedestal shallconsist of a 7.5 in. by 8.0 in. (191.0 mm by 203.2 mm) woodenpost approximately 18 in. (457.2 mm) long, capped with a steelplate approximately 12 by 12 in. (304.8 by 304.8 mm) and 1 in.(25.4 mm) thick. The wooden post s
31、hall be oak, yellow pine, orother wood having an average dry density of 42 to48 lb ft3(674.2 to 770.5 kg/m3). The wooden post shall besecured by bolts through four angle brackets to a solid concreteslab. The steel cap shall be firmly fastened to the post. Thepedestal assembly shall be installed so t
32、hat the post is plumband the cap is level.5.5 Specimen Mold HolderWith single-hammercompactors, the holder shall be mounted on the compactionpedestal so as to center the compaction mold over the center ofthe post. The holders shall hold the compaction mold, collar,and base plate securely in position
33、 during compaction of thespecimen.5.6 Ovens, Heating Pots or Hot PlatesCirculating airovens or thermostatically controlled heating pots and hot platesshall be provided for heating aggregates, asphalt material,specimen molds, compaction hammers, and other equipment towithin 5 F (3 C) of the required
34、mixing and compactiontemperatures. Suitable shields, baffle plates, or sand baths shallbe used on the surfaces of the hot plates to minimize localizedoverheating.5.7 Mixing ApparatusMechanical mixing isrecommended, but also can be mixed manually. Any type ofmechanical mixer may be used provided the
35、mix can bemaintained at the required temperature and mixing will pro-duce a well-coated, homogeneous mixture of the requiredamount in the allowable time, and further provided thatessentially all of the batch can be recovered. A metal pan orbowl of sufficient capacity for hand mixing may also be used
36、.5.8 Miscellaneous Equipment:5.8.1 Containers for Heating Aggregates, flat-bottom metalpans, or other suitable containers.5.8.2 Covered Containers for Heating Asphalt Binder, eithergill-type tins, beakers, pouring pots, or saucepans may be used.5.8.3 Mixing Tools, shall consist of a steel trowel (ma
37、sonspointing trowel with point rounded), spoon or spatula, forspading and hand mixing.D6926 1625.8.4 Thermometerthe thermometer shall be one of thefollowing:5.8.4.1 A liquid-in-glass thermometer of suitable range withsubdivisions and maximum scale error of 1.0 F (0.5 C) whichconforms to the requirem
38、ents of Specification E1. Calibrate thethermometer in accordance with one of the methods in TestMethod E77.5.8.4.2 A liquid-in-glass partial immersion thermometer ofsuitable range with subdivisions and maximum scale error of1.0 F (0.5 C) which conforms to the requirements of Speci-fication E2251. Ca
39、librate the thermometer in accordance withone of the methods in Test Method E77.5.8.4.3 Electronic thermometers may be used, for examplethermocouples, thermistors, or PRTs, with a readability of1.0 F (0.5 C) that has been calibrated as a system (probe andmeter).5.8.5 SievesThe sieve cloth and standa
40、rd sieves, given inSpecification E11, shall be mounted on substantial framesconstructed in a manner that will prevent loss of materialduring sieving.NOTE 5It is recommended that sieves mounted in frames larger thanstandard 8-in. (203.2-mm) diameter be used for testing coarse aggregatesto reduce the
41、possibility of overloading the sieves.5.8.6 Balance, readable to at least 0.1 g for batchingmixtures.5.8.7 Gloves, for handling hot equipment.5.8.8 Markers, for identifying specimens.5.8.9 Scoop, flat bottom, for batching aggregates.5.8.10 Spoon, large, for placing the mixture in the specimenmolds.i
42、n. (mm)A 4.100 to 4.150 (104.1 to 105.4)B 4.295 to 4.339 (109.1 to 110.2)C 4.490 to 4.560 (114.0 to 115.8)D 4.211 to 4.320 (107.0 to 109.7)E 3.990 to 4.005 (101.3 to 101.7)F 4.720 to 4.780 (119.9 to 121.4)G 3.980 to 3.990 (101.1 to 101.3)H 2.730 to 2.770 (69.3 to 70.4)J 0.120 to 0.285 (3.0 to 7.2)K
43、0.235 to 0.295 (6.0 to 7.5)L 3.420 to 3.460 (86.9 to 87.9)M 0.120 to 0.190 (3.0 to 4.8)N 0.485 to 0.585 (12.3 to 14.9)FIG. 1 Compaction MoldD6926 1636. Test Specimens6.1 Preparation of AggregatesDry aggregates to constantweight in an oven. Drying should be done at 230 6 9F(1106 5 C). After cooling,
44、separate the aggregates by dry-sievinginto the desired size fractions.3The following minimum sizefractions are recommended:1to34 in. (25 to 19 mm)34 to12 in. (19 to 12.5 mm)12 to38 in. (12.5 to 9.5 mm)38 to No. 4 (9.5 to 4.75 mm)No. 4 to No. 8 (4.75 to 2.36 mm)Passing No. 8 (2.36 mm)3Detailed requir
45、ements for these sieves are given in Specification E11.in. (mm)O P Drop Distance 17.94 to 18.06 (455.7 to 458.7)Q Guide Bushing . . . . . .R Guide Rod Nominal Diameter 0.625 (15.9)S Face Diameter Hardened Impact Resistant 3.860 to 3.960 (98.0 to 100.6)T Foot Thickness 0.450 to 0.550 (11.4 to 14.0)U
46、Weight Face Diameter 1.960 to 2.040 (49.8 to 51.8)X Spring . .Z Finger Guard 2.95 to 4.50 (75.0 to 114.3)lb. (kg)W Weight Mass 9.98 to 10.02 (4.527 to 4.545)FIG. 2 Manual Compaction HammerD6926 1646.2 Determination of Mixing and Compacting Tempera-tures:6.2.1 The asphalt binder used in preparing the
47、 samples mustbe heated to the range of mixing temperatures recommendedfor manufacturer/supplier or must be heated to the range ofmixing and compaction temperatures to produce a viscosity of170 6 20 cP (0.17 6 0.02 Pa.s) and 280 6 30 cP (0.28 60.03 Pa.s), respectively, for a binder density measured i
48、naccordance with Test Method D4402.NOTE 6Selection of mixing and compaction temperatures at viscosi-ties of 170 6 20 cP (0.17 6 0.02 Pas) and 280 6 30 cP (0.28 60.03 Pas), respectively, may not apply to modified binders. Modifiedasphalt binders, such as those produced with polymer additives or crumb
49、rubber, generally use mixing and compaction temperatures different thanindicated in 6.2.1. The user should contact the manufacturer to establishappropriate mixing and compaction temperature ranges.6.2.2 Cutback Asphalt MixtureThe temperature to which acutback asphalt must be heated to produce a viscosity of 170 620 cP (0.17 6 0.02 Pas) shall be the mixing temperature. Thecompaction temperature for a cutback asphalt mixture isselected using a compositional chart of viscosity versus percentsolvent for that cutback asphalt. From the com
