1、Designation: D 6857 03Standard Test Method forMaximum Specific Gravity and Density of BituminousPaving Mixtures Using Automatic Vacuum Sealing Method1This standard is issued under the fixed designation D 6857; 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 (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of maximumspecific gravity of and de
3、nsity 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
4、 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 limitations prior to use.1.4 A multi-laboratory precision for this
5、 standard has notbeen developed at this time. This standard should not be usedfor acceptance or rejection of a material for purchasingpurposes.2. Referenced Documents2.1 ASTM Standards:C 670 Practice for Preparing Precision and Bias Statementsfor Test Methods for Construction Materials2D 979 Practic
6、e for Sampling Bituminous Paving Mixtures3D 2041 Test Method for Theoretical Maximum SpecificGravity and Density of Bituminous Paving Mixtures3D 4311 Practice for Determination of Asphalt Volume Cor-rection to Base Temperature3D 4753 Specification for Evaluating, Selecting, and Speci-fying Balances
7、and Scales for Use in Soil, Rock, andConstruction Materials Testing4E 1 Specification for ASTM Thermometers5E 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method6E 1547 Terminology Relating to Industrial and SpecialtyChemicals73. Terminology3.1 The terms s
8、pecific gravity and density used in this testmethod are in accordance with the Terminology E 1547.3.2 Definitions: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 25C in inch-pound units.3.2.2 r
9、esidual 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 mass of anequal volume of water at the same temperature.4. Summary of Test Method4.1 A
10、 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 vacuum chamber. Air isevacuated from the sample to an absolute pressure of 5.6 mmHg and
11、 is automatically sealed. The bags containing the sampleare removed from the vacuum chamber and placed inside alarge water tank equipped with scales for weighing the sampleunder water. While completely submerged, the bag is cut openby scissors to allow the water to enter the bag. Since the sampleis
12、under complete vacuum, water will be forced around all theaccessible areas of the sample. The difference in weight in airand suspended weight in water will provide the sample volumeafter correcting for the bag influence. The dry weight and thevolume can be used to calculate the maximum specific grav
13、ityof the sample. This method is a rapid technique for determi-nation of maximum specific gravity that minimizes the expo-sure of bituminous samples to water during testing and reducesthe chance of water absorption.NOTE 1For porous aggregates, if water absorption correction is notperformed on the ma
14、ximum specific gravities obtained using this testmethod, the results may be higher than the results obtained by TestMethod D 2041. Without aggregate water absorption correction, air voidscalculated based on these results may be higher.1This test method is under the jurisdiction of ASTM Committee D04
15、 on Roadand Paving Materials and is the direct responsibility of Subcommittee D04.21 onSpecific Gravity and Density of Bituminous Mixtures.Current edition approved Jan. 10, 2003. Published March 2003. Originallyapproved in 2003. Last previous edition approved in 2003 as D 6857-03.2Annual Book of AST
16、M Standards, Vol 04.02.3Annual Book of ASTM Standards, Vol 04.03.4Annual Book of ASTM Standards, Vol 04.08.5Annual Book of ASTM Standards, Vol 14.03.6Annual Book of ASTM Standards, Vol 14.02.7Annual Book of ASTM Standards, Vol 15.05.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700,
17、West Conshohocken, PA 19428-2959, United States.5. Significance and Use5.1 The maximum 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 mater
18、ials.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 when calculating the amount ofbitumen absorbed by the internal porosity of the individualaggregate
19、particles in a bituminous paving mixture.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 equipped with a suitablea
20、pparatus 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 D 4753 as a class GP2balance.NO
21、TE 2Since 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),this means that the ba
22、lance must have a sensitivity capable of providingboth mass and volume values to at least four 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 m
23、inimum 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 mm(18 in.) and minimum depth of 460 mm (18 in.), for completelysubmerging the specimen in water while suspended.NOTE 3Setting the water tank at waist level will
24、 enable the user toconduct this test while standing and will significantly simplify theweighing operations.6.3 Vacuum Chamber8, 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 2000 g. The devic
25、e shall automatically seal the plasticbag and exhaust air back into the chamber in a controlledmanner 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
26、calibrated to bring the chamber toatmospheric pressure in 80 to 150 s, after the completion of thevacuum operation. The vacuum system should be providedwith a latch to control the chamber door opening.6.4 Absolute Vacuum Measurement Gage, independent ofthe vacuum sealing device which may be placed d
27、irectly insidethe chamber to verify vacuum performance and the chamberdoor sealing condition of the unit. The gage shall be capable ofreading pressure to 3 mm Hg.6.5 Plastic Bags, (Internal Bags), shall have random chan-nels built into at least one side of the bag to aid in evacuatingall the air fro
28、m the sample. The internal bag shall have aminimum opening of 305 mm (12 in.) and maximum openingof 340 mm (13.5 in.) and the outside plastic bag (external bag)shall have a minimum opening of 375 mm (14.75 in.) and amaximum opening of 394 mm (15.5 in.). The bags shall be ofplastic material that will
29、 not adhere to asphalt film, is punctureresistant, and is impermeable to air. The bags shall have aminimum thickness of 0.100 mm (0.004 in.) and maximumthickness of 0.152 mm (0.006 in.). The combined apparentspecific gravity of the two bags shall be provided by themanufacturer.NOTE 4Protect the plas
30、tic 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.6.7 Filler
31、 Plates, to position the sample and the bags in thesame plane as the sealing bar.6.8 Bag Cutting Knife, or scissors.6.9 Thermometers, calibrated liquid-in-glass thermometersof suitable range with subdivisions and maximum scale error of0.5C (0.9F), or any other thermostatic device of equalaccuracy, p
32、recision and sensitivity shall be used. Thermom-eters shall conform to the requirements of Specification E 1.7. Sampling7.1 Obtain the sample in accordance with Practice D 979.7.2 The size of the sample shall conform to the followingrequirements. Samples larger than 2000 g may be tested in1500-2000
33、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) 15004.75 (No. 4) 15008. Procedure8.1 Separate the particles of the sample of paving mixtureby hand, taking care to av
34、oid 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 manually, place it in a flat pan, and warmit in an oven until it can be separated as described.8.2 Unless the pav
35、ing mixture has been prepared in alaboratory using oven dry aggregates, oven-dry the sample to aconstant mass at a temperature of 105 6 5C (221 6 9F).Other methods of drying can be used as long as the sampleachieves a constant mass (mass repeats within 0.1 %). This8The sole source of supply of the a
36、pparatus 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 ma
37、y attend.D6857032drying 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 X1.2 in the Append
38、ix).8.4 Set the vacuum sealing machine according to the manu-factures recommendation to create at least a 5.6 mm Hgabsolute pressure inside the chamber.NOTE 5For asphalt mixture that contain polymers, the vacuum settingshould be held at 99 % of absolute vacuum for a minimum of five min.Follow manufa
39、cturers recommendations when performing tests on poly-merized mixtures.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 collectio
40、n table.8.7 Place the sample in the internal bag. Enure 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
41、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 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 awa
42、y 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
43、 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. The vacuum chamber shallautomatically seal the bag once the air is removed.8.15 Exhaust air into the chamber until the chamber dooropens indicating atmospheric p
44、ressure 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 visual inspection of the bag and listen for any leaks.NOTE 6While transferring the sample to the water bath
45、, 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 water bath at25C (77F) equipped with a scale.8.18 Submerge the sealed bag containing the sample com-pletely und
46、er 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 50 mm (2 in.) under water and remains underwater throughout the entire process.8.19 Open both bags with your finger
47、s and hold open for 10to 15 s to allow the water to flow in the bags.8.20 Reach into the bag with one hand and for 40 to 60 sbreak down all clumps with your fingers until there are noclumps larger than the maximum aggregate size used in themixture. With the other hand, fold the opening of the bagaro
48、und the arm that is used for breaking the sample.8.21 Secure the sample over a suspended scale and allowthe weight to stabilize. Make certain the bags or the suspensionequipment is not contacting the sides or the bottom of the watertank and that no part of the plastic bag is breaking the watersurfac
49、e at any time.8.22 Allow the scales to stabilize, and record the weight incolumn C of the data collection table.8.23 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(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 apparen
