1、Designation: D 6752 03e1Standard Test Method forBulk Specific Gravity and Density of Compacted BituminousMixtures Using Automatic Vacuum Sealing Method1This standard is issued under the fixed designation D 6752; the number immediately following the designation indicates the year oforiginal adoption
2、or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.e1NOTEParagraph 8.2 was corrected editorially in December 2004.1. Scope1.1 This test met
3、hod covers the determination of bulkspecific gravity of 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 i
4、n calculating the unit weight of themixture.1.4 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 regulat
5、ory requirements prior to use.2. Referenced Documents2.1 ASTM Standards:2C 670 Practice for Preparing Precision and Bias Statementsfor Test Methods for Construction MaterialsD 979 Practice for Sampling Bituminous Paving MixturesD 1461 Test Method for Moisture or Volatile Distillates inBituminous Pav
6、ing MixturesD 2726 Test Method for Bulk Specific Gravity and Densityof Non-Absorptive Compacted Bituminous MixturesD 3203 Test Method for Percent Air Voids in CompactedDense and Open Bituminous Paving MixturesD 4753 Guide for Evaluating, Selecting, and SpecifyingBalances and Standard Masses for Use
7、in Soil, Rock, andConstruction Materials Testing2.2 AASHTO Standards:3MP2 Standard Specification for Superpave Mix Design3. Significance and Use3.1 The results obtained from this method can be used todetermine the unit weight of compacted bituminous mixturesand in conjunction with Test Method D 3203
8、, 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 calculations that require units. Thisconversion is made by multiplying the specific gravity at agiven
9、temperature by the density of water at the same tempera-ture.3.3 This method can be used for 100 mm and 150 mmdiameter cylindrical as well as cubical asphalt specimens tocorrect for absorptive and open graded mixes. Mixes such asStone Matrix Asphalt (SMA), porous friction coarse, andSuperpave coarse
10、 graded mixes with significant surface textureand interconnected voids should be sealed for accurate bulkspecific density results. Follow manufacturer recommendationfor appropriate bag sizes to be utilized with cubical andabnormally shaped samples.44. Apparatus4.1 Balance, with ample capacity, and w
11、ith sufficient sensi-tivity to enable bulk specific gravity of specimens to becalculated to at least four 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 con
12、form to Guide D 4753 asa class GP2 balance.NOTE 1Since there are no more significant figures in the quotient(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 i
13、n air and in water), thismeans that the balance must have a sensitivity capable of providing both1This test method is under the jurisdiction of ASTM Committee D04 on Roadand Paving Materials and is the direct responsibility of Subcommittee D04.21 onSpecific Gravity and Density of Bituminous Mixtures
14、.Current edition approved Dec. 1, 2003. Published January 2004. Originallyapproved in 2002. Last previous edition approved in 2002 as D 6752-02a.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards
15、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, Washington, DC 20001.4Bulk specific gravity determined by this method may be lower than the resul
16、tsobtained by Test Method D 2726. As a result, air voids determined from these bulkspecific gravity values may be higher than the air voids values determined using TestMethod D 2726. These differences may be more pronounced for coarse aggregatemixtures. Users of this method are cautioned to evaluate
17、 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 Conshohocken, PA 19428-2959, United States.mass and volume values to at least four figures. For example,
18、a sensitivityof 0.1 g would provide four significant figures for the determination of amass in the range from 130.0 to 999.9 g when the specific gravity is 2.300.4.2 Water Bath, with minimum dimensions (Length 3Width 3 Depth) of 610 3 460 3 460 mm (24 3 18 3 18 in.)or a large cylindrical container,
19、for completely submerging thespecimen in water while suspended, equipped with an overflowoutlet for maintaining a constant water level.NOTE 2It is preferable to keep the water temperature constant byusing a temperature controlled heater. Also, to reduce the chance for thebag to touch the sides of th
20、e 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 inspected.4.3 Cushioned holder, for water displacement of the sample,having no s
21、harp edges.NOTE 3To 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) pumpcapable of evacuating a sealed and enclosed chamber to aminimum pressure of 10 mm Hg
22、in less than 60 s, when at sealevel. The chamber shall be large enough to seal samples of150 mm wide by 350 mm long by 150 mm thick. The deviceshall automatically seal the plastic bag and exhaust air backinto the chamber in a controlled manner to ensure properconformance of the plastic to the asphal
23、t specimen. The airexhaust and vacuum operation time should be calibrated at thefactory prior to initial use. The air exhaust system should becalibrated to bring the chamber to atmospheric pressure in 80to 120 s, after the completion of the vacuum operation. Thevacuum system should be provided with
24、a latch to control thechamber door opening.4.5 A Vacuum Measurement Gage, independent of thevacuum sealing device that could be placed directly inside thechamber to verify vacuum performance and the chamber doorsealing condition of the unit. The gage shall be capable ofreading 3 mm Hg (3 TORR) press
25、ure.4.6 Plastic Bags, used with the vacuum device shall be oneof the two following sizes. The smaller bags shall have aminimum opening of 235 mm (9.25 in.) and maximum openingof 260 mm (10.25 in.) and the larger bags shall have aminimum of 375 mm (14.75 in.) and a maximum opening of394 mm (15.5 in.)
26、. The bags shall be of plastic material thatwill not adhere to asphalt film, is puncture resistant, capable ofwithstanding sample temperatures of up to 70C, is imperme-able to water, containing no air channels for evacuation of airfrom the bag. The bags shall have a minimum thickness of0.100 mm (0.0
27、04 in.) and maximum thickness of 0.152 mm(0.006 in.). The apparent specific gravity for the bags shall beprovided by the manufacturer for each bag shipment. Theapparent specific gravity provided for each size bag shallaccount for the different sample weights and bag weight usedduring testing.4.7 Spe
28、cimen Sliding Plate, used within the chamber forreduction of friction on the plastic bags.4.8 Bag Cutting Knife, or scissors.4.9 Sufficient aggregate and asphalt binder to prepare alaboratory compacted sample of 4.75 mm design misture withminimum dimensions of 100 mm diameter by 60 mm thick.The comp
29、acted sample should be molded to create air voids inthe range of4%to8%at6%asphalt content. Refer toAASHTO MP2 provisional standard for instructions on how todesign 4.75 mm mixes. Refer toAASHTO provisional standardMP2, printed in 2003, for more information on 4.75 mm mixdesign.5. Sampling5.1 Test sp
30、ecimens may be molded from laboratory pre-pared samples or taken from bituminous pavement in the field.Field samples should be obtained in accordance with PracticeD 979.6. Test Specimens6.1 It is recommended, (1) that the diameter of cylindricallymolded or cored specimens, or the length of the sides
31、 of sawedspecimens be at least equal to four times the maximum size ofthe 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
32、avoid distortion, bending, or cracking ofspecimens during and after removal 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 evi
33、dent, they shall beremoved. Sealcoat or tackcoat, or both, may be removed bysawing the bottom or the top faces, or both, of the sample.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 edgesar
34、ound 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 D 2726 or ifthe mix is classified as an open graded mixture by the localmixture
35、 specifications. Follow the procedure outlined in thissection for determination of bulk specific gravity.7.2 Mass of Unsealed Specimen:7.2.1 Laboratory Prepared SpecimensDetermine themass of the specimen after it has cooled to room temperature.Designate this mass as A.7.2.2 Cores and Specimens Conta
36、ining MoistureDry thespecimen to constant mass. Designate this mass as A. Constantmass is defined as less than 0.05 % change in mass betweenconsecutive 15 minute drying intervals.7.3 Mass of Sealed Specimen:7.3.1 Select an appropriate size bag. For all 100 mm (4 in.)diameter samples and samples with
37、 150 mm (6 in.) diameterand less than 50 mm (2 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 largerD675203e12opening size bags as specified in 4.6. For samples that weighmore than 5500 g or abnor
38、mally shaped samples, use manu-facturers recommendation for appropriate bag size and con-figuration.NOTE 4Protect the bag during storage. Rough handling, storing inproximity to sharp objects such as tools, aggregate, or inside drawers willdamage the plastic bag. Refer to manufacturers recommendation
39、 forhandling and safe storage.7.3.2 Inspect an appropriate size bag for holes or irregulari-ties, record the bag weight and place a bag inside the vacuumchamber on top of the specimen sliding plate.7.3.3 Gently open the bag and place the specimen in theplastic bag on top of the specimen sliding plat
40、e, 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 chamber to remove the air from thechamber and the plastic bag. The vacuum chambe
41、r 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 opening ofthe door after completion of the test.7.3.6 Remove the sealed sa
42、mple 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 with a new bag.7.3.7 Determine the mass of the sealed specimen in air bysum
43、ming the weight in 7.2.2 and 7.3.2. Designate this mass asB.7.3.8 Determine the mass of the sealed specimen in a waterbath at 25C (77F). Designate this mass as E. Measure thetemperature of the water and if it is different from 25 6 1C(77 6 1.8F), a correction to the bulk specific gravity to 25Cmust
44、be made in accordance with 8.3.7.3.9 To ensure tight seal in the bag, remove the samplefrom water and cut the bag open. Remove 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, the
45、n dry and retest the sample,otherwise continue with the calculation step.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, g,C = fina
46、l 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:Density 5Bulk Specific Gravity!g (2)where:g = dens
47、ity of water at 25C (77F) (997.0 kg/m3, 0.997g/cm3or 62.24 lb/ft3).8.3 Correction for Water Bath Temperature Other Than25C (77F):8.3.1 For water temperature difference less than or equal to3C (5.4F), determine the specific gravity as follows:Bulk Specific Gravity at 25C 5 K Bulk at other temperature
48、!(3)where:K = determined from Table 1.8.3.2 For water temperature difference greater than 3C(5.4F), determine the correction based on the followingequation:Correction 5DTKsHC 1 B A!# E B AFTJ(4)where:DT = 25C minus the temperatureof the water bath,Ks=63 10-5ml/ml/C averagecoefficient of cubical ther
49、malexpansion of bituminousconcrete, andC+(B A)E(BA)/FT) = mass of the volume of waterfor the volume of the speci-men at 25C.8.3.3 The mass of displaced water can be corrected forwater temperatures difference greater than 3C (5.4F), by thefollowing equation:Bulk Specific Gravity 5ASC 1 B A!# E B AFT1 CorrectionD(5)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 Verification shall be perfor
