1、Designation: D6752/D6752M 17D6752/D6752M 18Standard Test Method forBulk Specific Gravity and Density of Compacted AsphaltMixtures Using Automatic Vacuum Sealing Method1This standard is issued under the fixed designation D6752/D6752M; the number immediately following the designation indicates theyear
2、 of original 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 bulk speci
3、fic gravity of compacted asphalt mixtures by the vacuum sealingmethod.1.2 This method can be used for compacted cylindrical and cubical laboratory and field asphalt mixture specimens.1.3 The bulk specific gravity of the compacted asphalt mixtures may be used in calculating the unit weight of the mix
4、ture.1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in eachsystem may not be exact equivalent;equivalents; therefore, each system shall be used independently of the other. Combining valuesfrom the two systems may result in no
5、nconformance with the standard.1.5 The text of this standard references notes and footnotes which provide explanatory material. These notes and footnotes(excluding those in tables and figures) shall not be considered as requirements of the standard.1.6 This standard does not purport to address all o
6、f the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine theapplicability of regulatory requirementslimitations prior to use.1.7 This international stan
7、dard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Refe
8、renced Documents2.1 ASTM Standards:2C670 Practice for Preparing Precision and Bias Statements for Test Methods for Construction MaterialsD8 Terminology Relating to Materials for Roads and PavementsD2726/D2726M Test Method for Bulk Specific Gravity and Density of Non-Absorptive Compacted Asphalt Mixt
9、uresD3203/D3203M Test Method for Percent Air Voids in Compacted Asphalt MixturesD3666 Specification for Minimum Requirements for Agencies Testing and Inspecting Road and Paving MaterialsD4753 Guide for Evaluating, Selecting, and Specifying Balances and Standard Masses for Use in Soil, Rock, and Cons
10、tructionMaterials TestingD5361/D5361M Practice for Sampling Compacted Asphalt Mixtures for Laboratory TestingD7227/D7227M Practice for Rapid Drying of Compacted Asphalt Mixture Specimens Using Vacuum Drying Apparatus2.2 AASHTO Standards:Standard:3M323 Standard Specification for Superpave Mix Design3
11、. Terminology3.1 For definitions of terms used in this standard, refer to Terminology D8.1 This test method is under the jurisdiction of ASTM Committee D04 on Road and Paving Materials and is the direct responsibility of Subcommittee D04.21 on SpecificGravity and Density of Asphalt Mixtures.Current
12、edition approved June 1, 2017Aug. 15, 2018. Published June 2017August 2018. Originally approved in 2002. Last previous edition approved in 20112017 asD6752/D6752M 11.D6752/D6752M 17. DOI: 10.1520/D6752_D6752M-17.10.1520/D6752_D6752M-18.2 For referencedASTM standards, visit theASTM website, www.astm.
13、org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 Available from the American Association of State Highway Transportation Officials (AASHTO), 441 N. Capitol Street, NW, Wash
14、ington, DC 20001.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users
15、consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14. Significance and Use4.1 The
16、results obtained from this method can be used to determine the unit weight of compacted asphalt mixtures, and inconjunction with Test Method D3203/D3203M, to obtain percent air voids. These values in turn may be used in determining therelative degree of compaction.4.2 Since specific gravity has no u
17、nits, it must be converted to density in order to do calculations that require units. Thisconversion is made by multiplying the specific gravity at a given temperature by the density of water at the same temperature.4.3 This method can be used for 100 mm 4 in. and 150 mm 6 in. 100 mm 4 in. and 150 m
18、m 6 in. diameter cylindricalas well as cubical asphalt mixture specimens to correct for inconsistencies in sample weight determinations resulting from drainageof water from samples and inaccuracy in saturated surface dry weight of absorptive coarse and open graded open-graded mixes.Asphalt mixes suc
19、h as stone matrix asphalt (SMA), porous friction course, and coarse graded coarse-graded mixes with significantsurface texture and interconnected voids can be tested with this method. Follow manufacturer recommendation for appropriate bagsizes to be utilized with cubical and abnormally shaped sample
20、s.4NOTE 1The quality of the results produced by this standard are dependent on the competence of the personnel performing the procedure and thecapability, calibration, and maintenance of the equipment used. Agencies that meet the criteria of Specification D3666 are generally considered capableof com
21、petent and objective testing, sampling, inspection, etc. Users of this standard are cautioned that compliance with Specification D3666 alone doesnot completely ensure reliable results. Reliable results depend on many factors; following the suggestions of Specification D3666 or some similaracceptable
22、 guideline provides a means of evaluating and controlling some of those factors.5. Apparatus5.1 Balance, with ample capacity, and with sufficient sensitivity to enable bulk specific gravity of specimens to be calculatedto at least four significant figures, that is, to at least three decimal places.
23、It shall be equipped with a suitable apparatus to permitweighing the specimen while it is suspended in water. The balance shall conform to Guide D4753 as a class GP2 balance.NOTE 2Since there are no more significant figures in the quotient (bulk specific gravity) than appear in either the dividend (
24、the mass of the specimenin air) or in the divisor (the volume of the specimen, obtained from the difference in mass of the specimen in air and in water), this means that the balancemust have a sensitivity capable of providing both mass and volume values to at least four figures. For example, a sensi
25、tivity of 0.1 g 0.00022 lb wouldprovide four significant figures for the determination of a mass in the range from 130.0 to 999.9 g 0.29 to 2.20 lb when the specific gravity is 2.300.5.2 Water Bath, with minimum dimensions (length width depth) of 610 by 460 by 460 mm 24 by 18 by 18 in. or a largecyl
26、indrical container, for completely submerging the specimen in water while suspended, equipped with an overflow outlet formaintaining a constant water level.NOTE 3It is preferable to keep the water temperature constant by using a temperature-controlled heater.Also, to reduce the chance for the bag to
27、 touchthe sides of the water tank, it is preferable to elevate the water tank to a level at which the sample can be placed on the weighing mechanism while standingup, and the placement of the sample and the bag in the water tank can easily be inspected.5.3 Cushioned Holder, for water displacement of
28、 the sample, having no sharp edges.NOTE 4To avoid accidental puncture of the plastic bags in the water bath, plastic-coated cushioned holders have been found to work well for thistest method.5.4 Vacuum Chamber, with a 0.93 kW 1.25 hp 0.93-kW 1.25-hp pump capable of evacuating a sealed and enclosed c
29、hamberto a minimum 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 by 150 mm 6 in. thick. The device shall automatically seal the plasticbag and exhaust air back into the chamber in a contr
30、olled manner to ensure proper conformance of the plastic to the asphaltspecimen. The air exhaust and vacuum operation time should be calibrated at the factory prior to initial use. The air exhaust systemshould be calibrated to bring the chamber to atmospheric pressure in 80 to 120 s, after the compl
31、etion of the vacuum operation.The vacuum system should be provided with a latch to control the chamber door opening.5.5 Vacuum Measurement Gauge, independent of the vacuum sealing device that could be placed directly inside the chamber,to verify vacuum performance and the chamber door sealing condit
32、ion of the unit. The gauge shall be capable of reading 3 mmHg 3 Torr pressure.5.6 Plastic Bags, used with the vacuum device shall be one of the two following sizes. The smaller bags shall have a minimumopening of 241 mm 9.50 in. and maximum opening of 260267 mm 10.25 in.10.50 in., and the larger bag
33、s shall have aminimum of 375368 mm 14.7514.50 in. and a maximum opening of 394 mm 15.5 in. The bags shall be of plastic materialthat will not adhere to asphalt film, is puncture resistant, is capable of withstanding sample temperatures of up to 70 C 158 F,is impermeable to water, and contains no air
34、 channels for evacuation of air from the bag. The bags shall have a minimum thicknessof 0.1000.127 mm 0.0040.005 in. and maximum thickness of 0.1520.178 mm 0.0060.007 in. The apparent specific gravity4 Bulk specific gravity determined by this method may be lower than the results obtained by Test Met
35、hod D2726/D2726M. As a result, air voids determined from thesebulk specific gravity values may be higher than the air voids values determined using Test Method D2726/D2726M. These differences may be more pronounced for coarseaggregate mixtures. Users of this method are cautioned to evaluate any alte
36、ration in percent asphalt content or aggregate gradations for mix designs with a known positiveperformance history.D6752/D6752M 182for the bags shall be provided by the manufacturer. The apparent specific gravity provided for each size bag shall account for thedifferent sample weights and bag weight
37、 used during testing.5.7 Specimen Sliding Plate, used within the chamber for reduction of friction on the plastic bags.5.8 Bag-Cutting Knife, or scissors.6. Sampling6.1 Test specimens may be molded from laboratory-prepared samples or taken from asphalt pavement in the field. Field samplesshould be o
38、btained in accordance with Practice D5361/D5361M.7. Test Specimens7.1 It is recommended, (1) that the diameter of cylindrically molded or cored specimens, or the length of the sides of sawedspecimens be at least equal to four times the maximum size of the aggregate; and (2) that the thickness of spe
39、cimens be at leastone and one-half one-and-one-half times the maximum size of the aggregate. Pavement specimens are to be taken by such meansas coring, sawing of blocks, and so forth.7.2 Take care to avoid distortion, bending, or cracking of specimens during and after removal from pavement or mold.
40、Storespecimens in a safe, cool place.7.3 Specimens shall be free of foreign materials such as sealcoat, tack coat, foundation material, soil, paper, or foil. When anyof these materials is visually evident, it shall be removed. Sealcoat, tackcoat, or irregular surfaces that may result in the plastic
41、bagnot complying with the sample shall be removed by sawing the bottom or the top faces, or both, of the sample.7.4 If desired, specimens may be separated from other pavement layers by sawing or other suitable means.7.5 Use a brush or a soft sanding block to break sharp edges around the top and bott
42、om corners of the sample.8. Procedure8.1 This procedure can be used for compacted field and laboratory specimens. Specifically, use this procedure if the asphalt mixis absorptive as determined by Test Method D2726/D2726M and for coarse and open graded open-graded mixes. For asphalt mixessuch as ston
43、e matrix asphalt (SMA), porous friction course, and coarse graded coarse-graded mixes with significant surface textureand interconnected voids, follow the procedure outlined in this section for determination of bulk specific gravity.8.2 Mass of Unsealed Specimen:8.2.1 Laboratory-Prepared SpecimensDe
44、termine the mass of the specimen after it has cooled to room temperature. Designatethis mass as A.8.2.2 Cores and Specimens Containing MoistureDry the specimen and designate this mass as A. Vacuum drying, PracticeD7227/D7227M, or other approved methods may be used to dry the sample to constant mass.
45、8.3 Mass of Sealed Specimen:8.3.1 Select an appropriate size bag. For all 100 mm 4 in. diameter samples and samples with 150 mm 6 in. diameter andless than 75 mm 3 in. thickness, use the bag with smaller opening size as specified in 5.6. For 150 mm 6 in. samples with greaterthan 50 mm 2 in. thicknes
46、s, use the larger opening size bags as specified in 5.6. For samples that weigh more than 5500 g 12.1lb or abnormally shaped samples, use manufacturers recommendation for appropriate bag size and configuration.NOTE 5Protect the bag during storage. Rough handling, storing in proximity to sharp object
47、s such as tools, aggregate, or inside drawers will damagethe plastic bag. Refer to manufacturers recommendation for handling and safe storage.8.3.2 Inspect an appropriate size bag for holes or irregularities, record the bag mass, and place a bag inside the vacuum chamberon top of the specimen slidin
48、g plate.8.3.3 Gently open the bag and place the specimen in the plastic bag on top of the specimen sliding plate, being careful to handlethe bag in such a manner that would prevent a puncture. Avoid dropping or impacting the bag, and follow manufacturersrecommendations for handling the specimens and
49、 the bags.8.3.4 Allow the vacuum chamber to remove the air from the chamber and the plastic bag. The vacuum chamber shallautomatically seal the bag once the air is removed.8.3.5 Exhaust air into the chamber until the chamber door opens, indicating atmospheric pressure within the chamber. Thechamber door latch can be used to avoid automatic opening of the door after completion of the test.8.3.6 Remove the sealed sample from the vacuum chamber. Handle the sealed sample with extreme care to prevent punctur
