1、Designation: D6857 09Standard Test Method forMaximum Specific Gravity and Density of BituminousPaving Mixtures Using Automatic Vacuum Sealing Method1This standard is issued under the fixed designation D6857; the number immediately following the designation indicates the year oforiginal adoption or,
2、in the case of revision, the year of last revision. 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 test method covers the determination of maximumspecific gravity of and densi
3、ty of uncompacted bituminouspaving mixtures at 25C (77F).1.2 The values stated in SI units are to be regarded as thestandard. The other units given may be approximate and aregiven to help the user interpret units on available standardequipment used with this test method.1.3 This standard does not pu
4、rport 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 limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C
5、670 Practice for Preparing Precision and Bias Statementsfor Test Methods for Construction MaterialsD979 Practice for Sampling Bituminous Paving MixturesD2041 Test Method for Theoretical Maximum SpecificGravity and Density of Bituminous Paving MixturesD4753 Guide for Evaluating, Selecting, and Specif
6、yingBalances and Standard Masses for Use in Soil, Rock, andConstruction Materials TestingE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE1547 Terminology Relating to Industrial and SpecialtyChemicalsD3666 Specification for Minimum Requirements for Age
7、n-cies Testing and Inspecting Road and Paving Materials3. Terminology3.1 The terms specific gravity and density used in this testmethod are in accordance with the Terminology E1547.3.2 Definitions:3.2.1 density, as determined by this test methodthe massof a cubic meter of the material at 25C in SI u
8、nits, or the massof a cubic foot of the material at 77F in inch-pound units.3.2.2 residual pressure, as employed by this test methodthe pressure in a vacuum chamber when vacuum is applied.3.2.3 specific gravity, as determined by this test methodthe ratio of a given mass of material at 25C to the mas
9、s of anequal volume of water at the same temperature.4. Summary of Test Method4.1 A weighed sample of oven-dry paving mixture in theloose condition at room temperature is placed inside a speciallydesigned channel bag. The bag containing the sample is placedinside another bag and placed inside a vacu
10、um chamber. Air isevacuated from the sample to an absolute pressure of 6.0 mmHg (6 Torr) and is automatically sealed. The bags containingthe sample are removed from the vacuum chamber and placedinside a large water tank equipped with scales for weighing thesample under water. While completely submer
11、ged, the bag iscut open by scissors to allow the water to enter the bag. Sincethe sample is under complete vacuum, water will be forcedaround all the accessible areas of the sample. The difference inweight in air and suspended weight in water will provide thesample volume after correcting for the ba
12、g influence. The dryweight and the volume can be used to calculate the maximumspecific gravity of the sample. This method is a rapid techniquefor determination of maximum specific gravity that minimizesthe exposure of bituminous samples to water during testing andreduces the chance of water absorpti
13、on.NOTE 1For porous aggregates, if water absorption correction is notperformed on the maximum specific gravities obtained using this test1This test method is under the jurisdiction of ASTM Committee D04 on Roadand Paving Materials and is the direct responsibility of Subcommittee D04.21 onSpecific Gr
14、avity and Density of Bituminous Mixtures.Current edition approved Dec. 1, 2009. Published January 2010. Originallyapproved in 2003. Last previous edition approved in 2003 as D6857 03. DOI:10.1520/D6857-09.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer S
15、ervice 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 States.method, the results may be higher than th
16、e results obtained by TestMethod D2041. Without aggregate water absorption correction, air voidscalculated based on these results may be higher.5. Significance and Use5.1 The maximum specific gravities and densities of bitu-minous paving mixtures are intrinsic properties whose valuesare influenced b
17、y the composition of the mixture in terms oftypes and amounts of aggregates and bituminous materials.5.1.1 They are used to calculate values for percent air voidsin compacted bituminous paving mixtures.5.1.2 They provide target values for the compaction ofpaving mixtures.5.1.3 They are essential whe
18、n calculating the amount ofbitumen absorbed by the internal porosity of the individualaggregate particles in a bituminous paving mixture.NOTE 2The personnel and equipment used in performing this test canbe evaluated in accordance with Practice D3666.6. Apparatus6.1 Balance, with ample capacity, and
19、with sufficient sensi-tivity to enable maximum 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 suspension wi
20、re attached to the scalesshould break the surface of the water at a single point andshould have a maximum diameter of 3 mm (0.125 in.). Thebalance shall conform to Specification D4753 as a class GP2balance.NOTE 3Since there are no more significant figures in the quotient(maximum specific gravity) th
21、an appear in either the dividend (the massof the specimen in 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 balance must have a sensitivity capable of providingboth mass and volume values to at least fo
22、ur figures. For example, asensitivity of 0.1 g would provide four significant figures for thedetermination of a mass in the range from 130.0 to 999.9 g when thespecific gravity is 2.300.6.2 Water Bath, with minimum dimensions (Length 3Width 3 Depth) of 610 3 460 3 460 mm (24 3 18 3 18 in.)or a cylin
23、drical container with a minimum diameter of 460 mm(18 in.) and minimum depth of 460 mm (18 in.), for completelysubmerging the specimen in water while suspended.NOTE 4Setting the water tank at waist level will enable the user toconduct this test while standing and will significantly simplify theweigh
24、ing operations.6.3 Vacuum Chamber3, with a 0.93 kW (1.25 hp) pumpcapable of evacuating a sealed and enclosed chamber to 5.6mm Hg. The chamber shall be large enough to seal samples aslarge as 2200 g. The device shall automatically seal the plasticbag and exhaust air back into the chamber in a control
25、ledmanner to ensure proper conformance of the plastic to theasphalt mixture. The air exhaust and vacuum operation timeshould be calibrated at the factory prior to initial use. The airexhaust system should be calibrated to bring the chamber toatmospheric pressure in 80 to 150 s, after the completion
26、of thevacuum operation. The vacuum system should be providedwith a latch to control the chamber door opening.6.4 Absolute Vacuum Measurement Gauge, independent ofthe vacuum sealing device which may be placed directly insidethe chamber to verify vacuum performance and the chamberdoor sealing conditio
27、n of the unit. The gauge shall be capableof reading pressure to 3 mm Hg (3 Torr).6.5 Plastic Bags, consisting of inner plastic bag (internalbag) having random channels built into one side of the bag,with minimum and maximum bag opening sizes of 305 mm (12in.) and 340 mm (13.5 in.), respectively, and
28、 outer plastic bag(external bag) with minimum and maximum opening sizes of375 mm (14.75 in.) and 394 mm (15.5 in.), repectively. Thebags shall be of plastic material that will not adhere to asphaltfilm, is puncture resistant, and is impermeable to air. Each bagshall have a minimum thickness of 0.100
29、 mm (0.004 in.) andmaximum thickness of 0.152 mm (0.006 in.). The combinedapparent specific gravity of the two bags shall be provided bythe manufacturer.NOTE 5Protect the plastic bags during storage. Rough handling,storing in close proximity to sharp objects, near aggregates, or insidedrawers will d
30、amage the plastic bags. Refer to manufacturers proceduresfor safe handling and storage of bags.6.6 Holder, for water displacement of the sample having nosharp edges.6.7 Filler Plates, to position the sample and the bags in thesame plane as the sealing bar.6.8 Bag Cutting Knife, or scissors.6.9 Therm
31、ometric Device, a temperature measuring devicereadable to 0.5C (1F) and accurate to 0.3C (0.5F) formonitoring the temperature of the water bath.6.10 Laboratory oven, capable of heating the asphalt sampleto 110 6 5C (230 6 9F)7. Sampling7.1 Obtain the sample in accordance with Practice D979.7.2 The s
32、ize of the sample shall conform to the followingrequirements. Samples larger than 2200 g may be tested in15002000 g portions at a time.Size of Largest Particle ofAggregate in Mixture, mm (in.)Minimum Sample Size,g50.0 (2) 600037.5 (1.5) 400025.0 (1) 250019.0 (0.75) 200012.5 (0.5) 15009.5 (0.375) 150
33、04.75 (No. 4) 15008. Procedure8.1 Separate the particles of the sample of paving mixtureby hand, taking care to avoid fracturing the aggregate, so thatthe particles of the fine aggregate portion are not larger than 6.3mm (14 in.). If a sample of paving mixture is not sufficientlysoft to be separated
34、 manually, place it in a flat pan, and warmit in an oven until it can be separated as described.3The sole source of supply of the apparatus and the method known to thecommittee at this time is InstroTek, Inc., Raleigh, NC. If you are aware of alternativesuppliers, please provide this information to
35、ASTM Headquarters. Your commentswill receive careful consideration at a meeting of the responsible technicalcommittee,1which you may attend.D6857 0928.2 Unless the paving mixture has been prepared in alaboratory using oven dry aggregates, oven-dry the sample to aconstant mass at a temperature of 110
36、 6 5C (230 6 9F).Other methods of drying can be used as long as the sampleachieves a constant mass (mass repeats within 0.1 %). Thisdrying and any required warming for particle separation asdescribed in 8.1 should be combined as a single operation tominimize reheating effects.8.3 Cool the sample to
37、room temperature and record theweight. (Refer to column B of the data collection table. SeeTable X1.1 in the Appendix).8.4 Set the vacuum sealing machine according to the manu-factures recommendation to create 99 % of absolute vacuumfor a minimum of five minutes inside the chamber.NOTE 6For asphalt
38、mixture that contain polymers, follow manufac-turers recommendations.8.5 If after examining the external bag there are no punc-tures or cuts, weigh one channel (internal) and one examinednon channel (external) bag.8.6 Record the combined weight of the bags in column A ofthe attached data collection
39、table.8.7 Place the sample in the internal bag. Ensure that nosample is lost during this transfer.8.8 Place the empty external bag inside the vacuum cham-ber.8.9 Place the internal bag containing the sample with thechannel side (rough side) down into the external bag. Therough side is placed under t
40、he sample to protect against trappedair and to help in the evacuation of the air from the bag.8.10 Spread the sample so that it is evenly distributed withinthe internal bag. Do not spread the sample by squeezing downon the sample from outside the bag.8.11 Push in the opening of the internal bag away
41、 from theopening of the external bag to prevent the opening of theinternal bag from being sealed. Make sure that the opening ofthe internal bag is flat and that the opening is not restricted bya fold in the bag.8.12 Place the opening of the external bag over the seal barmaking sure the internal bag
42、is not over the seal bar.8.13 Close the chamber door.8.14 Allow the vacuum chamber to remove the air from thechamber and the plastic bag. Follow the manufacturers recom-mendations for proper machine settings and time required forthe vacuum cycle. The vacuum chamber shall automaticallyseal the bag on
43、ce the air is removed.8.15 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.8.16 Remove the sealed sample from the vacuum chamber.Perform a
44、 visual inspection of the bag and listen for any leaks.NOTE 7While transferring the sample to the water bath, handle thesealed sample with extreme care. Avoid impact with hard surfaces. Impactcan cause leaks in the bag and allow air to enter the sample.8.17 Immediately transfer the sample to the wat
45、er bath at25 6 1C (77 6 2F) equipped with a scale.8.18 Submerge the sealed bag containing the sample com-pletely under water and cut open the external bag all the wayacross the top, leaving approximately 25 mm (1 in.) intact.When cutting the bag, make certain the sealed portion of thebag is at least
46、 50 mm (2 in.) under water and remains underwater throughout the entire process.8.19 Open both bags with your fingers and hold open for 10to 15 s to allow the water to flow in the bags.8.20 Secure the sample over a suspended scale. Makecertain the bags or the suspension equipment is not contactingth
47、e sides or the bottom of the water tank and that no part of theplastic bag is breaking the water surface at any time.8.21 Record the weight in Column C of the data collectiontable.8.22 Perform the calculation according to Section 9 or usecomputer software for automatic calculation of the maximumspec
48、ific gravity.9. Calculations9.1 Calculate the maximum specific gravity of the pavingmixture as follows:Maximum Specific Gravity 5BA 1 B C AVc(1)where:B = mass of dry specimen in air, g,A = combined mass of two plastic bags, (one channel andone external bag), g,C = mass of paving mixture and the bags
49、 underwater, g,andVc= combined apparent specific gravity of the two plasticbags at 25C (77F), provided by the manufacturer.9.2 Calculate the density of the specimen as follows:Density 5Maximum Specific Gravity!g (2)where:g = density of water at 25C (77F) (997.0 kg/m3, 0.997g/cm3or 62.24 lb/ft3).10. Verification10.1 The vacuum settings of the device should be verifiedonce every three months, after major repairs, after eachshipment or relocation. Verification should be performed withan absolute vacuum gauge capable of being placed inside thechambe
