1、Designation: D6752/D6752M 11Standard Test Method forBulk Specific Gravity and Density of Compacted BituminousMixtures Using Automatic Vacuum Sealing Method1This standard is issued under the fixed designation D6752/D6752M; the number immediately following the designation indicates theyear of original
2、 adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of bulkspecific gravity o
3、f compacted bituminous mixtures by thevacuum sealing method.1.2 This method can be used for compacted cylindrical andcubical bituminous laboratory and field specimens.1.3 The bulk specific gravity of the compacted bituminousmixtures may be used in calculating the unit weight of themixture.1.4 The va
4、lues stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalent; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standar
5、d.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory requirements prior to use.2. Reference
6、d Documents2.1 ASTM Standards:2C670 Practice for Preparing Precision and Bias Statementsfor Test Methods for Construction MaterialsD2726 Test Method for Bulk Specific Gravity and Densityof Non-Absorptive Compacted Bituminous MixturesD3203 Test Method for Percent Air Voids in CompactedDense and Open
7、Bituminous Paving MixturesD3666 Specification for Minimum Requirements for Agen-cies Testing and Inspecting Road and Paving MaterialsD4753 Guide for Evaluating, Selecting, and SpecifyingBalances and Standard Masses for Use in Soil, Rock, andConstruction Materials TestingD5361 Practice for Sampling C
8、ompacted Bituminous Mix-tures for Laboratory TestingD7227 Practice for Rapid Drying of Compacted AsphaltSpecimens Using Vacuum Drying Apparatus2.2 AASHTO Standards:3M323 Standard Specification for Superpave Mix Design3. Significance and Use3.1 The results obtained from this method can be used todete
9、rmine the unit weight of compacted bituminous mixturesand in conjunction with Test Method D3203, to obtain percentair voids. These values in turn may be used in determining therelative degree of compaction.3.2 Since specific gravity has no units, it must be convertedto density in order to do calcula
10、tions that require units. Thisconversion is made by multiplying the specific gravity at agiven temperature by the density of water at the same tempera-ture.3.3 This method can be used for 100 mm 4 in. and 150 mm6 in. diameter cylindrical as well as cubical asphalt speci-mens to correct for inconsist
11、encies in sample weight determi-nations resulting from drainage of water from samples andinaccuracy in saturated surface dry weight of absorptive coarseand open graded mixes. Mixes such as Stone Matrix Asphalt(SMA), porous friction course, and coarse graded mixes withsignificant surface texture and
12、interconnected voids can betested with this method. Follow manufacturer recommendationfor appropriate bag sizes to be utilized with cubical andabnormally shaped samples.41This test method is under the jurisdiction of ASTM Committee D04 on Roadand Paving Materials and is the direct responsibility of
13、Subcommittee D04.21 onSpecific Gravity and Density of Bituminous Mixtures.Current edition approved June 1, 2011. Published July 2011. Originally approvedin 2002. Last previous edition approved in 2009 as D6752 09. DOI: 10.1520/D6752_D6752M-11.2For referenced ASTM standards, visit the ASTM website, w
14、ww.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.3Available from the American Association of State Highway TransportationOfficials (AASHTO), 441 N. Capitol Street, NW,
15、 Washington, DC 20001.4Bulk specific gravity determined by this method may be lower than the resultsobtained by Test Method D2726. As a result, air voids determined from these bulkspecific gravity values may be higher than the air voids values determined using TestMethod D2726. These differences may
16、 be more pronounced for coarse aggregatemixtures. Users of this method are cautioned to evaluate any alteration in percentasphalt content or aggregate gradations for mix designs with a known positiveperformance history.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohoc
17、ken, PA 19428-2959, United States.NOTE 1The personnel and equipment used in performing this test canbe evaluated in accordance with Practice D3666.4. Apparatus4.1 Balance, with ample capacity, and with sufficient sensi-tivity to enable bulk specific gravity of specimens to becalculated to at least f
18、our significant figures, that is to at leastthree decimal places. It shall be equipped with a suitableapparatus to permit weighing the specimen while it is sus-pended in water. The balance shall conform to Guide D4753 asa class GP2 balance.NOTE 2Since there are no more significant figures in the quo
19、tient(bulk specific gravity) than appear in either the dividend (the mass of thespecimen in air) or in the divisor (the volume of the specimen, obtainedfrom the difference in mass of the specimen in air and in water), thismeans that the balance must have a sensitivity capable of providing bothmass a
20、nd volume values to at least four figures. For example, a sensitivityof 0.1 g 0.00022 lb would provide four significant figures for thedetermination of a mass in the range from 130.0 to 999.9 g 0.29 to 2.20lb when the specific gravity is 2.300.4.2 Water Bath, with minimum dimensions (Length 3Width 3
21、 Depth) of 610 3 460 3 460 mm 24 3 18 3 18 in.or a large cylindrical container, for completely submerging thespecimen in water while suspended, equipped with an overflowoutlet for maintaining a constant water level.NOTE 3It is preferable to keep the water temperature constant byusing a temperature c
22、ontrolled heater. Also, to reduce the chance for thebag to touch the sides of the water tank, it is preferable to elevate the watertank to a level at which the sample can be placed on the weighingmechanism while standing up, and the placement of the sample and thebag in the water tank can easily be
23、inspected.4.3 Cushioned holder, for water displacement of the sample,having no sharp edges.NOTE 4To avoid accidental puncture of the plastic bags in the waterbath, plastic coated cushioned holders have been found to work well forthis test method.4.4 Vacuum Chamber, with a 0.93 kW (1.25 hp) pumpcapab
24、le of evacuating a sealed and enclosed chamber to aminimum pressure of 10 mm Hg (10 Torr) in less than 60 s,when at sea level. The chamber shall be large enough to sealsamples of 150 mm 6 in. wide by 350 mm 14 in. long by150 mm 6 in. thick. The device shall automatically seal theplastic bag and exha
25、ust air back into the chamber in acontrolled manner to ensure proper conformance of the plasticto the asphalt specimen. The air exhaust and vacuum operationtime should be calibrated at the factory prior to initial use. Theair exhaust system should be calibrated to bring the chamber toatmospheric pre
26、ssure in 80 to 120 s, after the completion of thevacuum operation. The vacuum system should be providedwith a latch to control the chamber door opening.4.5 A Vacuum Measurement Gauge, independent of thevacuum sealing device that could be placed directly inside thechamber to verify vacuum performance
27、 and the chamber doorsealing condition of the unit. The gauge shall be capable ofreading 3 mm Hg (3 Torr) pressure.4.6 Plastic Bags, used with the vacuum device shall be oneof the two following sizes. The smaller bags shall have aminimum opening of 241 mm 9.50 in. and maximum openingof 260 mm 10.25
28、in. and the larger bags shall have aminimum of 375 mm 14.75 in. and a maximum opening of394 mm 15.5 in. The bags shall be of plastic material thatwill not adhere to asphalt film, is puncture resistant, is capableof withstanding sample temperatures of up to 70C 158F, isimpermeable to water, and conta
29、ins no air channels forevacuation of air from the bag. The bags shall have a minimumthickness of 0.100 mm 0.004 in. and maximum thickness of0.152 mm 0.006 in. The apparent specific gravity for thebags shall be provided by the manufacturer. The apparentspecific gravity provided for each size bag shal
30、l account for thedifferent sample weights and bag weight used during testing.4.7 Specimen Sliding Plate, used within the chamber forreduction of friction on the plastic bags.4.8 Bag Cutting Knife, or scissors.5. Sampling5.1 Test specimens may be molded from laboratory pre-pared samples or taken from
31、 bituminous pavement in the field.Field samples should be obtained in accordance with PracticeD5361.6. Test Specimens6.1 It is recommended, (1) that the diameter of cylindricallymolded or cored specimens, or the length of the sides of sawedspecimens be at least equal to four times the maximum size o
32、fthe aggregate; and (2) that the thickness of specimens be atleast one and one half times the maximum size of theaggregate. Pavement specimens are to be taken by such meansas coring, sawing of blocks, and so forth.6.2 Take care to avoid distortion, bending, or cracking ofspecimens during and after r
33、emoval from pavement or mold.Store specimens in a safe, cool place.6.3 Specimens shall be free of foreign materials, such assealcoat, tack coat, foundation material, soil, paper, or foil.When any of these materials are visually evident, they shall beremoved. Sealcoat, tackcoat or irregular surfaces
34、that mayresult in the plastic bag not complying with the sample shall beremoved by sawing the bottom or the top faces, or both, of thesample.6.4 If desired, specimens may be separated from otherpavement layers by sawing or other suitable means.6.5 Use a brush or a soft sanding block to break sharp e
35、dgesaround the top and bottom corners of the sample.7. Procedure7.1 This procedure can be used for compacted field andlaboratory specimens. Specifically, use this procedure, if themix is absorptive as determined by Test Method D2726 and forcoarse and open graded mixes. For mixes such as Stone Matrix
36、Asphalt (SMA), porous friction course, and coarse gradedmixes with significant surface texture and interconnectedvoids, follow the procedure outlined in this section for deter-mination of bulk specific gravity.7.2 Mass of Unsealed Specimen:7.2.1 Laboratory Prepared SpecimensDetermine themass of the
37、specimen after it has cooled to room temperature.Designate this mass as A.D6752/D6752M 1127.2.2 Cores and Specimens Containing MoistureDry thespecimen and designate this mass as A. Vacuum drying D7227or other approved methods may be used to dry the sample toconstant mass.7.3 Mass of Sealed Specimen:
38、7.3.1 Select an appropriate size bag. For all 100 mm 4 in.diameter samples and samples with 150 mm 6 in. diameterand less than 75 mm 3 in. thickness, use the bag with smalleropening size as specified in 4.6. For 150 mm 6 in. sampleswith greater than 50 mm 2 in. thickness, use the largeropening size
39、bags as specified in 4.6. For samples that weighmore than 5500 g 12.1 lb or abnormally shaped samples, usemanufacturers recommendation for appropriate bag size andconfiguration.NOTE 5Protect the bag during storage. Rough handling, storing inproximity to sharp objects such as tools, aggregate, or ins
40、ide drawers willdamage the plastic bag. Refer to manufacturers recommendation forhandling and safe storage.7.3.2 Inspect an appropriate size bag for holes or irregulari-ties, record the bag mass and place a bag inside the vacuumchamber on top of the specimen sliding plate.7.3.3 Gently open the bag a
41、nd place the specimen in theplastic bag on top of the specimen sliding plate, being carefulto handle the bag in such a manner that would prevent apuncture. Avoid dropping or impacting the bag, and followmanufacturers recommendations for handling the specimensand the bags.7.3.4 Allow the vacuum chamb
42、er to remove the air from thechamber and the plastic bag. The vacuum chamber shallautomatically seal the bag once the air is removed.7.3.5 Exhaust air into the chamber until the chamber dooropens indicating atmospheric pressure within the chamber. Thechamber door latch can be used to avoid automatic
43、 opening ofthe door after completion of the test.7.3.6 Remove the sealed sample from the vacuum chamber.Handle the sealed sample with extreme care to preventpuncturing the bag. Gently pull on the bag and if the bag easilyseparates from the sample, the bag may be punctured; repeatthe sealing process
44、with a new bag.7.3.7 Immediately place the sample in the water tank on topof the weighing mechanism and determine the mass of thesealed specimen in a water bath at 25 6 1C 77 6 2F.Designate this mass as E.7.3.8 To ensure tight seal in the bag, remove the samplefrom water and cut the bag open. Remove
45、 the sample from thebag and determine its mass. Designate this mass as C. Comparethis mass with initial dry mass in 7.2.1 (mass A). If mass C isgreater than mass A by 5 g, then dry and retest the sample,otherwise continue with the calculation step.7.3.9 Calculate the mass of the sealed specimen in a
46、ir bysumming the masses in either 7.2.1 or 7.2.2 and 7.3.2.Designate this mass as B.8. Calculations8.1 Calculate the bulk specific gravity of the sealed speci-men as follows:Bulk Specific Gravity 5AC 1 B A!# E B AFT(1)where:A = initial mass of dry specimen in air, g,B = mass of dry, sealed specimen,
47、 g (A + mass of plasticbag from 7.3.2),C = final mass of specimen after removal from sealed bag,g,E = mass of sealed specimen underwater, g, andFT= apparent specific gravity of plastic sealing material at25C 77F, provided by the manufacturer.8.2 Calculate the density of the specimen as follows:Densi
48、ty 5Bulk Specific Gravity!g (2)where:g = density of water at 25C 77F (997.0 kg/m3, 0.997g/cm3or 62.24 lb/ft3).9. Verification9.1 System Verification:9.1.1 The vacuum settings of the device shall be verifiedonce every three months, after major repairs, after eachshipment or relocation.9.1.2 Verificat
49、ion shall be performed with a vacuum gaugecapable of being placed inside the chamber and reading thevacuum setting of the sealing device.9.1.3 Place the gauge inside the chamber and record thesetting. The gauge should indicate a reading of 10 mm Hg 10Torr or less. The unit shall not be used if the gauge reading isabove 10 mm Hg 10 Torr.9.1.4 Vacuum gauge used for verification shall be standard-ized once every 12 months.NOTE 6On line vacuum gages, while capable of indicating vacuumperformance of the pu
