1、Designation: D 6926 04Standard Practice forPreparation of Bituminous Specimens Using MarshallApparatus1This standard is issued under the fixed designation D 6926; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last rev
2、ision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers preparation and compaction of 102mm (4 in.) diameter by nominal 64 mm (2.5 in.) highcylindrical bitumino
3、us paving mixture specimens by means ofthe original manual Marshall method and subsequent variationsof the method. This practice is intended for use with laboratoryand plant produced bituminous mixtures with aggregate up to25 mm (1 in.) maximum size and for recompaction of asphaltpavement samples.1.
4、2 There are three types of Marshall compaction apparatusin use. The following types of hammer arrangements areincluded in this practice:1.2.1 Manually held hammer handle attached to a flatcompaction foot through a spring loaded swivel and is handoperated (original standard developed by the Corps of
5、Engi-neers).1.2.2 Hammer handle restrained laterally (fixed) but notvertically attached to a flat compaction foot through a springloaded 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 o
6、per-ate at (1) nominal 55 blows per minute and (2) equal to orgreater than 75 blows per minute.1.2.3 Hammer handle restrained laterally (fixed) with con-stant surcharge on top of hammer, a slanted compaction foot,rotating mold base, and is mechanically operated.1.3 Although the mass and height of ma
7、ss 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 user to establish the specific required number of blows tobe used for compaction of the specimen in relation to the field.2. Referenced Documents2.1 ASTM S
8、tandards:2D 2171 Test Method for Viscosity of Asphalts by VacuumCapillary ViscometerD 2493 Viscosity-Temperature Chart for AsphaltsD 4402 Test Method for Viscosity Determinations of As-phalt at Elevated Temperature Using a Brookfield Ther-mosel ApparatusE11 Specification for Wire Cloth and Sieves fo
9、r TestingPurposes3. Significance and Use3.1 Compacted bituminous mixture specimens molded bythis procedure are used for various physical tests such asstability, flow, indirect tensile strength, fatigue, creep, andmodulus. Density and voids analysis are also conducted onspecimens for mixture design a
10、nd evaluation of field compac-tion.NOTE 1Uncompacted mixtures are used for determination of theo-retical maximum specific gravity.4. Apparatus4.1 Specimen Mold AssemblyMold cylinders, base plates,and extension collars shall conform to the details shown in Fig.1.4.2 Specimen ExtractorThe specimen ext
11、ractor shall havea steel disk that will enter the mold without binding and not beless than 100 mm (3.95 in.) in diameter and 12.5 mm (12 in.)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
12、 jack apparatus or a leverarm device may be used, provided the specimens are notdeformed during the extraction process.4.3 Compaction Hammers:4.3.1 Compaction Hammers with a Manually Held (Type 1)or Fixed (Type 2) Handle, either mechanically or hand operatedas generally shown in Fig. 2, shall have a
13、 flat, circularcompaction foot with spring loaded swivel and a 4.54 6 0.01kg (10 6 0.02 lb) sliding mass with a free fall of 457.2 6 1.5mm (18 6 0.06 in.) (see Fig. 2 for hammer tolerances). Amechanical hammer is shown in Fig. 3.NOTE 2Manual compaction hammers should be equipped with afinger safety
14、guard.1This practice is under the jurisdiction of ASTM Committee D04 on Road andPaving Materials and is the direct responsibility of Subcommittee D04.20 onMechanical Tests of Bituminous Mixes.Current edition approved Aug. 1, 2004. Published August 2004.2For referenced ASTM standards, visit the ASTM
15、website, 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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United
16、States.4.3.2 Compaction Hammers with a Fixed Hammer Handle,surcharge on top of handle, constantly rotating base, andmechanically operated (Type 3) as generally shown in Fig. 4shall have a slanted, circular tamping face and a 4.54 6 0.01 kg(10 6 0.02 lb) sliding weight with a free fall of 457.2 6 1.5
17、mm (18 6 0.06 in.) (see Fig. 2 and Fig. 4 for hammer andtamping face bevel angle and tolerances, respectively). Arotating mechanism is incorporated in the base. The baserotation rate and hammer blow rate shall be 18 to 30 rpm and64 6 4 blows per minute, respectively.NOTE 3Type 3 Marshall hammer appa
18、ratus are available in versionswith more than one hammer. Multiple hammer operation will affectspecimen density. Best comparative results will be obtained by compact-ing all specimens with the same hammer and with no other hammersoperating.4.4 Compaction PedestalThe compaction pedestal shallconsist
19、of a nominal 203.2 by 203.2 mm (8 by 8 in.) woodenpost approximately 457 mm (18 in.) long capped with a steelplate approximately 304.8 by 304.8 mm (12 by 12 in.) and 25.4mm (1 in.) thick. The wooden post shall be oak, yellow pine,or other wood having an average dry density of 670 to 770kg/m3(42 to 4
20、8 lb/ft3). The wooden post shall be secured bybolts through four angle brackets to a solid concrete slab. Thesteel cap shall be firmly fastened to the post. The pedestalassembly shall be installed so that the post is plumb and the capis level.mm in.A 104.1 to 105.4 4.100 to 4.150B 109.1 to 110.2 4.2
21、95 to 3.439C 114.0 to 115.8 4.490 to 4.560D 107.0 to 109.7 4.211 to 4.320E 101.3 to 101.7 3.990 to 4.005F 119.9 to 121.4 4.720 to 4.780G 101.1 to 101.3 3.980 to 3.990H 69.3 to 70.4 2.730 to 2.770J 7.0 to 7.2 0.235 to 0.285K 6.1 to 6.7 0.235 to 0.265L 86.9 to 87.9 3.420 to 3.460M 3.0 to 4.8 0.120 to
22、0.190N 12.3 to 14.9 0.485 to 0.585FIG. 1 Compaction MoldD69260424.5 Specimen Mold-HolderWith single hammer compac-tors, the holder shall be mounted on the compaction pedestal soas to center the compaction mold over the center of the post.Specimen mold-holders of multi-hammer compactors are notnecess
23、arily centered. The holders shall hold the compactionmold, collar, and base plate securely in position duringcompaction of the specimen.4.6 Ovens, Heating Pots or Hot PlatesCirculating airovens or thermostatically controlled heating pot and hot platesshall be provided for heating aggregates, bitumin
24、ous material,specimen molds, compaction hammers, and other equipment towithin 3C (5F) of the required mixing and compactiontemperatures. Suitable shields, baffle plates, or sand baths shallbe used on the surfaces of the hot plates to minimize localizedoverheating.4.7 Mixing ApparatusMechanical mixin
25、g is recom-mended. Any type of mechanical mixer may be used providedthe mix can be maintained at the required temperature andmixing will produce a well-coated, homogeneous mixture ofthe required amount in the allowable time, and further providedthat essentially all of the batch can be recovered. A m
26、etal panor bowl of sufficient capacity for hand mixing may also beused.4.8 Miscellaneous Equipment:4.8.1 Containers for Heating Aggregates, flat-bottom metalpans, or other suitable containers.4.8.2 Covered Containers for Heating Bituminous Material,either gill-type tins, beakers, pouring pots, or sa
27、ucepans maybe used.4.8.3 Mixing Tools, shall consist of a steel trowel (Masonspointing trowel with point rounded), spoon or spatula, forspading and hand mixing.4.8.4 Calibrated Thermometers, for determining tempera-tures of aggregates, bitumen, and bituminous mixtures.Armored-glass or dial-type ther
28、mometers with metal stems arerecommended. A range from 10 to 200C (50 to 400F) withsensitivity of 3C (5F) is required.4.8.5 Balance, readable to at least 0.1 g for batchingmixtures.4.8.6 Gloves, for handling hot equipment.mm in.O minus P 456.6 to 457.8 17.975 to 18.025Q Bronze bushings R Minimum nom
29、inal diameter of 0.625 in. (15.9 mm)and with suitable corrosion resistance15.9 0.625S Face hardened. Impact resistant material 98.0 to 100.0 3.860 to 3.950T 11.5 to 14.0 0.450 to 0.550U 49.8 to 51.8 1.960 to 2.040kg lbW 4.53 to 4.55 9.98 to 10.02X Spring loaded swivel between guide rod and footdetai
30、ls optional FIG. 2 Manual Compaction HammerD69260434.8.7 Marking Crayons, for identifying specimens.4.8.8 Scoop, flat bottom, for batching aggregates.4.8.9 Spoon, large, for placing the mixture in the specimenmolds.5. Test Specimens5.1 Preparation of AggregatesDry aggregates to constantweight. Oven
31、drying should be done at 105 to 110C (221 to230F). After cooling, separate the aggregates by dry-sievinginto the desired size fractions.3The following minimum sizefractions are recommended:25 to 19 mm (1 to34 in.)19 to 12.5 mm (34 to12 in.)12.5 to 9.5 mm (12 to38 in.)9.5to4.75mm(38 to No. 4)4.75 to
32、2.36 mm (No. 4 to No. 8)2.36 mm (Passing No. 8)5.2 Determination of Mixing and Compacting Tempera-tures:5.2.1 The asphalt cement used in preparing the samplesmust be heated to produce viscosities of 0.17 6 0.02 Pas and0.28 6 0.03 Pas for mixing and compacting, respectively. Anexample of a viscosity
33、temperature chart is given in Fig. 2 ofD 2493.NOTE 4Selection of mixing and compaction temperatures at viscosi-ties of 0.17 6 0.02 Pas and 0.28 6 0.03 Pas, respectively, may not applyto modified binders. The user should contact the manufacturer to establishappropriate mixing and compaction temperatu
34、re ranges.5.2.2 Cutback Asphalt MixtureThe temperature to whicha cutback asphalt must be heated to produce a viscosity of 0.173Detailed requirements for these sieves are given in ASTM Specification E11.FIG. 3 Mechanical HammerFIG. 4 Slanted Foot, Rotating Base CompactorD69260446 0.02 Pas shall be th
35、e mixing temperature. The compactiontemperature for a cutback asphalt mixture is selected using acompositional chart of viscosity versus percent solvent for thatcutback asphalt. From the compositional chart, determine thecutback asphalts percentage of solvent by weight from itsviscosity at 60C (140F
36、) after it has lost 50 percent of itssolvent (for rapid-cure and medium-cure cutbacks) or 20percent of its solvent (for slow cure cutbacks). The compactiontemperature is determined from the viscosity temperature chartas that to which the cutback asphalt must be heated to producea viscosity of 0.28 6
37、 0.03 Pas after losing the specifiedamount of original solvent.5.2.3 Recompacted Paving MixturesMaterials obtainedfrom an existing pavement shall be warmed in coveredcontainers in an oven to within 3C (5F) of the desiredcompaction temperature. Heating should only be long enoughto achieve desired com
38、paction temperature. If the compactiontemperature for a specific mixture is not known, experience hasshown that these mixes should be compacted at a temperaturebetween 120C (250F) and 135C (275F). In preparation forheating to compaction temperature the material should bewarmed and worked until a loo
39、se mixture condition is ob-tained.Any cut aggregate can be removed. Stability of reheatedand recompacted mixtures from existing pavements is likely tobe higher than the original mixture due to in service hardeningof the binder. The reheating process will have only minorinfluence on binder hardening.
40、5.3 Mixture PreparationSpecimens may be preparedfrom single batches or multiple batches containing sufficientmaterial for three or four specimens.5.3.1 Weigh into separate containers the amount of eachaggregate size fraction required to produce a batch that willresult in one, two, three, or four com
41、pacted specimens 63.5 62.5 mm (2.5 6 0.1 in.) in height (about 1200, 2400, 3600 or4800 g, respectively). Place aggregate batches in containers ona hot plate or in an oven and heat to a temperature above butnot exceeding the mixing temperature established in 5.2 bymore than 28C (50F) for asphalt ceme
42、nt and tar mixes and14C (25F) for cutback asphalt mixes. Charge the mixingcontainer with the heated aggregate and dry mix thoroughly(approximately 5 s) with scoop or spoon. Form a crater in thedry blended aggregate and weigh the required amount ofbituminous material at mixing temperature into the mi
43、xture.For mixes prepared with cutback asphalt, introduce the mixingblade in the mixing bowl and determine the total weight of themix components plus bowl and blade before proceeding withmixing. Care must be exercised to prevent loss of the mixduring mixing and subsequent handling. At this point, the
44、mixture temperature shall be within the limits of the mixingtemperature established in 5.2. Mix the aggregate and bitumi-nous material rapidly until thoroughly coated for approxi-mately 60 s for single-specimen batches and approximately120 s for multiple-specimen batches.5.3.2 Condition single batch
45、es in covered metal containersin an oven at a temperature 8C (15F) to 11C (20F) abovethe compaction temperature established in 5.2 for a minimumof 1 h and a maximum of 2 h.5.3.3 For multiple batched sample, place the entire batch orsample on a clean non-absorptive surface. Hand mix to ensureuniformi
46、ty and quarter into appropriate sample size to conformto specimen height requirements. For asphalt cements and tarmixtures, put the samples into metal containers and cover.Place the covered metal containers in a ventilated oven at thetemperature established in 5.3.2 to condition for a minimum of1 h
47、and a maximum of 2 h. Cure cutback asphalt mixture in themixing bowl in a ventilated oven maintained at approximately11C (20F) above the compaction temperature. Curing is to becontinued in the mixing bowl until precalculated weight of 50% solvent loss or more has been obtained. The mix may bestirred
48、 in the mixing bowl during curing to accelerate thesolvent loss. However, care should be exercised to prevent mixloss. Weigh the mix during curing in successive intervals of 15min initially and less than 10 min intervals as the weight of themix at 50 % solvent loss is approached.5.3.4 Other bitumino
49、us or plant-produced materials mayrequire special curing techniques.NOTE 5Heating mixtures for a period of time prior to compactionmay result in specimens having properties that are different from thosethat are compacted immediately after mixing (original Marshall criteriaare based on a no-cure procedure).5.4 Compaction of Specimens:5.4.1 Thoroughly clean the specimen mold assembly andthe face of the compaction hammer and heat them either inboiling water, in an oven, or on a hot plate to a temperaturebetween 90 and 150C (2
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