1、Designation: D6926 10Standard Practice forPreparation of Bituminous 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 revis
2、ion. 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 102mm (4 in.) diameter by nominal 64 mm (2.5 in.) highcylindrical bituminous
3、paving mixture specimens by means ofthe original manual Marshall method and subsequent variationsof the method (Test Method D6927). This practice is intendedfor use with laboratory and plant produced bituminous mix-tures with aggregate up to 25 mm (1 in.) maximum size and forrecompaction of asphalt
4、pavement samples.1.2 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 develop
5、ed by the Corps of 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 a
6、re available that oper-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 ma
7、ss and height 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 user to establish the specific required number of blows tobe used for compaction of the specimen in relation to the field.1.4 UnitsThe v
8、alues 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 material
9、. These notes and footnotes(excluding those in tables and figures) shall not be consideredas requirements of the standard.2. Referenced Documents2.1 ASTM Standards:2D2493 Standard Viscosity-Temperature Chart for AsphaltsD3666 Specification for Minimum Requirements for Agen-cies Testing and Inspectin
10、g Road and Paving MaterialsD6927 Test Method for Marshall Stability and Flow ofBituminous MixturesE11 Specification for Woven Wire Test Sieve Cloth and TestSieves3. Significance and Use3.1 Compacted bituminous mixture specimens molded bythis procedure are used for various physical tests such asstabi
11、lity, flow, indirect tensile strength, fatigue, creep, andmodulus. Density and voids analysis are also conducted onspecimens for mixture design and evaluation of field compac-tion.NOTE 1Uncompacted mixtures are used for determination of theo-retical maximum specific gravity.4. Apparatus4.1 Specimen
12、Mold AssemblyMold cylinders, base plates,and extension collars shall conform to the details shown in Fig.1.4.2 Specimen ExtractorThe specimen extractor shall havea steel disk that will enter the mold without binding and not beless than 3.95 in. (100 mm) in diameter and12 in. (12.5 mm)thick. The stee
13、l 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 the specimens are notdeformed during the extraction process.4.3 Compaction Hammers:4.3.1 Compacti
14、on Hammers with a Manually Held (Type 1)or Fixed (Type 2) Handle, either mechanically or hand operated1This 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 Mixtures.Current e
15、dition approved June 15, 2010. Published September 2010. Originallyapproved in 2004. Last previous edition approved in 2004 as D692604 DOI:10.1520/D6926-10.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of AST
16、MStandards 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 States.as generally shown in Fig. 2, shall have a flat, circularcompaction foot with spring loade
17、d swivel and a 10 6 0.02 lb(4.54 6 0.01 kg) sliding mass with a free fall of 18 6 0.06 in.(457.2 6 1.5 mm) (see Fig. 2 for hammer tolerances).Atypicalmechanical hammer is shown in Fig. 3.NOTE 2Manual compaction hammers should be equipped with afinger safety guard.4.3.2 Compaction Hammers with a Fixe
18、d 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 (4.54 6 0.01 kg) slidingweight with a free fall of 18 6 0.06 in. (457.2 6 1.5 mm) (seeFig. 2 for hammer and tamping face bevel angle a
19、nd tolerances,respectively).Arotating mechanism is incorporated in the base.The base rotation rate and hammer blow rate shall be 18 to 30rpm and 64 6 4 blows per minute, respectively.NOTE 3Type 3 Marshall hammer apparatus are available in versionswith more than one hammer. Multiple hammer operation
20、will affectspecimen density and is not recommended. Best comparative results willbe obtained by compacting all specimens with the same hammer and withno other hammers operating.4.4 Compaction PedestalThe compaction pedestal shallconsist of a nominal 8 by 8 in. (203.2 by 203.2 mm) woodenpost approxim
21、ately 18 in. (457 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 shall be oak, yellow pine, orother wood having an average dry density of 42 to 48lb/ft3(670 to 770 kg/m3). The wooden post shall be secured byin. (mm)A 4.100 t
22、o 4.150 (104.1 to 105.4)B 4.295 to 3.439 (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 0.235 to 0.285 (7.0 to 7.2)K 0.235 to 0.265 (
23、6.1 to 6.7)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 102FIG. 2 Manual Compaction HammerD6926 103bolts through four angle brackets to a solid concrete slab. Thesteel cap shall be firmly fastened to the post. The pedestalasse
24、mbly shall be installed so that the post is plumb and the capis level.4.5 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 not
25、necessarily 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, b
26、ituminous material,specimen molds, compaction hammers, and other equipment towithin 5F (3C) 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
27、 mixing 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 recovere
28、d. A metal 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,
29、 or saucepans 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 Thermometer(s)temperature measuring device(s)readable to 2F (1C) for checking mixing and compactingtemperatures.4.8.5 Calibrated
30、 Thermometers, for determining tempera-tures of aggregates, bitumen, and bituminous mixtures.Armored-glass or dial-type thermometers with metal stems arerecommended. A range from 50 to 400F (10 to 200C) withsensitivity of 3C (5F) is required.NOTE 4Standardization practices specified in Specification
31、 D3666 arerecommended for the thermometer used in this test method. Dial ther-mometer may exhibit inaccuracies due to frequently use or mishandling.It is recommended that the standardization of dial thermometers beconducted more frequently by a comparison to a reference thermometricdevice of equal o
32、r greater readability at a temperature within the range ofintended use.4.8.6 Balance, readable to at least 0.1 g (0.004 oz (avoir)for batching mixtures.4.8.7 Gloves, for handling hot equipment.4.8.8 Marking Crayons, for identifying specimens.4.8.9 Scoop, flat bottom, for batching aggregates.4.8.10 S
33、poon, large, for placing the mixture in the specimenmolds.5. Test Specimens5.1 Preparation of AggregatesDry aggregates to constantweight. Oven drying should be done at 105 to 110C (221 to230F). After cooling, separate the aggregates by dry-sievinginto the desired size fractions.3The following minimu
34、m 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)5.2 Determination of Mixing and Compacting Tempera-tures:5.2.1 The asphalt cement used in preparing the sam
35、plesmust be heated to produce viscosities of 170 6 20 cP (0.17 60.02 Pas) and 0.28 6 0.03 Pas (280 6 30 cP) for mixing andcompacting, respectively. An example of a viscosity tempera-ture chart is given in Fig. 2 of D2493.3Detailed requirements for these sieves are given in ASTM Specification E11.FIG
36、. 3 Typical Mechanical HammerD6926 104NOTE 5Selection 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 6 0.03Pas), respectively, may not apply to modified binders. The user shouldcontact the manufacturer to establish appropriate mixing and
37、compactiontemperature ranges.5.2.2 Cutback Asphalt MixtureThe temperature to whicha cutback asphalt must be heated to produce a viscosity of 1706 20 cP (0.17 6 0.02 Pas) shall be the mixing temperature.The compaction temperature for a cutback asphalt mixture isselected using a compositional chart of
38、 viscosity versus percentsolvent for that cutback asphalt. From the compositional chart,determine the cutback asphalts percentage of solvent byweight from its viscosity at 140F (60C) after it has lost 50percent of its solvent (for rapid-cure and medium-cure cut-backs) or 20 percent of its solvent (f
39、or slow cure cutbacks). Thecompaction temperature is determined from the viscositytemperature chart as that to which the cutback asphalt must beheated to produce a viscosity of 280 6 30 cP (0.28 6 0.03Pas) after losing the specified amount of original solvent.5.2.3 Recompacted Paving MixturesMateria
40、ls obtainedfrom an existing pavement shall be warmed in coveredcontainers in an oven to within 5F (3C) of the desiredcompaction temperature. Heating should only be long enoughto achieve desired compaction temperature. If the compactiontemperature for a specific mixture is not known, experience hassh
41、own that these mixes should be compacted at a temperaturebetween 250F (120C) and 275F (135C). In preparation forheating to compaction temperature the material should bewarmed and worked until a loose mixture condition is ob-tained.Any cut aggregate can be removed. Stability of reheatedand recompacte
42、d 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.5.3 Mixture PreparationSpecimens may be preparedfrom single batches or multiple batches containing suff
43、icientmaterial 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 compacted specimens 2.5 60.1 in. (63.5 6 2.5 mm) in height (about 1200, 2400, 3600 or4800 g, respectively)
44、. 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 50F (28C) for asphalt cement and tar mixes and25F (14C) for cutback asphalt mixes. Charge the mixingcontainer with the heated agg
45、regate 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 mixture.For mixes prepared with cutback asphalt, introduce the mixingblade in the mixing bowl and determi
46、ne 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, themixture temperature shall be within the limits of the mixingtemperature established in 5.2. Mix the agg
47、regate 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 batches in covered metal containersin an oven at a temperature 15F (8C) to 20F (11C) abovethe compaction tem
48、perature 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 ensureuniformity and quarter into appropriate sample size to conformto specimen height requirements. For asphalt ceme
49、nts 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 and a maximum of 2 h. Cure cutback asphalt mixture in themixing bowl in a ventilated oven maintained at approximately20F (11C) 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 in the mixing bowl during c
