1、Designation: D6857/D6857M 11Standard Test Method forMaximum Specific Gravity and Density of BituminousPaving Mixtures Using Automatic Vacuum Sealing Method1This standard is issued under the fixed designation D6857/D6857M; 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 maximumspecific gravit
3、y of and density of uncompacted bituminouspaving mixtures at 25C 77F.1.2 The values 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. Com
4、biningvalues from the two systems may result in non-conformancewith the standard.1.3 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 de
5、termine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C670 Practice for Preparing Precision and Bias Statementsfor Test Methods for Construction MaterialsD979 Practice for Sampling Bituminous Paving MixturesD2041 Test Method for Theoretical Maxi
6、mum SpecificGravity and Density of Bituminous Paving MixturesD4753 Guide for Evaluating, Selecting, and SpecifyingBalances and Standard Masses for Use in Soil, Rock, andConstruction Materials TestingE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE1547
7、 Terminology Relating to Industrial and SpecialtyChemicalsD3666 Specification for Minimum Requirements for Agen-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 Defin
8、itions:3.2.1 density, as determined by this test methodthe massof a cubic meter of the material at 25C in SI units, 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.
9、2.3 specific gravity, as determined by this test methodthe ratio of a given mass of material at 25C 77F to the massof an equal 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
10、 speciallydesigned channel bag. The bag containing the sample is placedinside another bag and placed inside a vacuum 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
11、placedinside a large water tank equipped with scales for weighing thesample under water. While completely submerged, 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 di
12、fference inweight in air and suspended weight in water will provide thesample volume after correcting for the bag 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
13、that minimizesthe exposure of bituminous samples to water during testing andreduces the chance of water absorption.NOTE 1For porous aggregates, if water absorption correction is notperformed on the maximum specific gravities obtained using this testmethod, the results may be higher than the results
14、obtained by TestMethod D2041. Without aggregate water absorption correction, air voids1This 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.Current ed
15、ition approved June 1, 2011. Published July 2011. Originally approvedin 2003. Last previous edition approved in 2009 as D6857 09. DOI: 10.1520/D6857_D6857M-11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of
16、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.calculated based on these results may be higher.5. Significance and Use5.1 The maximum
17、specific gravities and densities of bitu-minous paving mixtures are intrinsic properties whose valuesare influenced by 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 bitumino
18、us paving mixtures.5.1.2 They provide target values for the compaction ofpaving mixtures.5.1.3 They are essential when 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 perf
19、orming this test canbe evaluated in accordance with Practice D3666.6. Apparatus6.1 Balance, with ample capacity, and 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
20、 equipped with a suitableapparatus to permit weighing the specimen while it is sus-pended in water. The suspension wire 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
21、 a class GP2balance.NOTE 3Since there are no more significant figures in the quotient(maximum specific gravity) than 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),
22、this means that the balance must have a sensitivity capable of providingboth mass and volume values to at least four figures. For example, asensitivity of 0.1 g 0.00022 lb would provide four significant figures forthe determination of a mass in the range from 130.0 to 999.9 g 0.29 to2.20 lb when the
23、 specific 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 cylindrical container with a minimum diameter of 460 mm18 in. and minimum depth of 460 mm 18 in., for completelysubmerging the specimen in water while suspended.NOTE
24、4Setting the water tank at waist level will enable the user toconduct this test while standing and will significantly simplify theweighing 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 6 Torr. The chamber shall be large e
25、nough to sealsamples as large as 2200 g 4.85 lb. The device shallautomatically seal the plastic bag and exhaust air back into thechamber in a controlled manner to ensure proper conformanceof the plastic to the asphalt mixture. The air exhaust andvacuum operation time should be calibrated at the fact
26、ory priorto initial use. The air exhaust system should be calibrated tobring the chamber to atmospheric pressure in 80 to 150 s, afterthe completion of the vacuum operation. The vacuum systemshould be provided with a latch to control the chamber dooropening.6.4 Absolute Vacuum Measurement Gauge, ind
27、ependent ofthe vacuum sealing device which may be placed directly insidethe chamber to verify vacuum performance and the chamberdoor sealing condition 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 r
28、andom 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 outer plastic bag(external bag) with minimum and maximum opening sizes of375 mm 14.75 in. and 394 mm 15.5 in., respectively. Thebags shall be of plastic mat
29、erial that will not adhere to asphaltfilm, is puncture resistant, and is impermeable to air. Each bagshall have a minimum thickness of 0.100 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 5Protec
30、t the plastic bags during storage. Rough handling,storing in close proximity to sharp objects, near aggregates, or insidedrawers will damage 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.
31、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 Thermometric 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, cap
32、able of heating the asphalt sampleto 110 6 5C 230 6 9F7. Sampling7.1 Obtain the sample in accordance with Practice D979.7.2 The size of the sample shall conform to the followingrequirements. Samples larger than 2200 g 4.85 lb may betested in 15002000 g 3.31-4.41 lb portions at a time.Size of Largest
33、 Particle ofAggregate in Mixture, mm in.Minimum Sample Size,g50.0 2 600013.2337.5 1.5 40008.8225.0 1 25005.5119.0 0.75 20004.4112.5 0.5 15003.319.5 0.375 15003.314.75 0.187 15003.318. Procedure8.1 Separate the particles of the sample of paving mixtureby hand, taking care to avoid fracturing the aggr
34、egate, 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 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
35、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 ASTM Headquarters. Your commentswill receive careful consideration at a meeting of the responsible technicalcommittee,1which you may attend.
36、D6857/D6857M 1128.2 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 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 %). Thisdry
37、ing 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 room temperature and record theweight. (Refer to column B of the data collection table. SeeTable X1.1 in the Appendix).8.4 Set the vacu
38、um 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 mixture that contain polymers, follow manufac-turers recommendations.8.5 If after examining the external bag there are no punc-tures or
39、 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 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 insi
40、de 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 the 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 even
41、ly 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 from theopening of the external bag to prevent the opening of theinternal bag from being sealed. Make sure that the opening ofthe inte
42、rnal 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 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 ba
43、g. Follow the manufacturers recom-mendations for proper machine settings and time required forthe vacuum cycle. The vacuum chamber shall automaticallyseal the bag once the air is removed.8.15 Exhaust air into the chamber until the chamber dooropens indicating atmospheric pressure within the chamber.
44、 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 visual inspection of the bag and listen for any leaks.NOTE 7While transferring the sample to the water bath, handle thesealed sample w
45、ith 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 water 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
46、 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 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
47、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 contactingthe 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 i
48、n Column C of the data collectiontable.8.22 Perform the calculation according to Section 9 or usecomputer software for automatic calculation of the maximumspecific gravity.9. Calculations9.1 Calculate the maximum specific gravity of the pavingmixture as follows:Maximum Specific Gravity 5BA 1 B C AVc
49、(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 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. Ve
