1、Designation: D6857/D6857M 17D6857/D6857M 18Standard Test Method forMaximum Specific Gravity and Density of Asphalt MixturesUsing Automatic Vacuum Sealing Method1This standard is issued under the fixed designation D6857/D6857M; the number immediately following the designation indicates theyear of ori
2、ginal 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 maximum specific
3、gravity and density of uncompacted asphalt mixtures at25 C 77 F.1.2 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 o
4、ther. Combining valuesfrom the two systems may result in nonconformance with the standard.1.3 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 s
5、tandard.1.4 This standard does not purport to address all of 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 limit
6、ations prior to use.1.5 This international standard 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 Tech
7、nical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2C670 Practice for Preparing Precision and Bias Statements for Test Methods for Construction MaterialsD979/D979M Practice for Sampling Bituminous Paving MixturesD2041/D2041M Test Method for Theoretical Maximum Specific
8、 Gravity and Density of Bituminous Paving 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 ConstructionMaterials TestingE691
9、Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test MethodE1547 Terminology Relating to Industrial and Specialty Chemicals3. Terminology3.1 The terms specific gravity and density used in this test method are in accordance with the Terminology E1547.3.2 Definitions:3
10、.2.1 density, as determined by this test methoddensityas determined by this test method, the mass of a cubic meter of thematerial at 25 C in SI units, or the mass of a cubic foot of the material at 77 F in inch-pound units.3.2.2 residual pressure, as employed by this test methodpressureas employed b
11、y this test method, the pressure in a vacuumchamber when vacuum is applied.3.2.3 specific gravity, as determined by this test methodgravityas determined by this test method, the ratio of a given massof material at 25 C 77 F to the mass of an equal volume of water at the same temperature.1 This test
12、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 edition approved June 1, 2017Aug. 15, 2018. Published June 2017August 2018. Originally approved in 20
13、03. Last previous edition approved in 20112017 asD6857/D6857M 11.D6857/D6857M 17. DOI: 10.1520/D6857_D6857M-17.10.1520/D6857_D6857M-18.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume info
14、rmation, refer to the standards Document Summary page on the ASTM website.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 d
15、epict all changes accurately, ASTM recommends that users 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
16、19428-2959. United States14. Summary of Test Method4.1 A weighed sample of oven-dryoven-dried asphalt mixture in the loose condition at room temperature is placed inside aspecially designed channel bag. The bag containing the sample is placed inside another bag and placed inside a vacuum chamber.Air
17、 is evacuated from the sample to an absolute pressure of 6.0 mm Hg 6 Torr and is automatically sealed. The bags containingthe sample are removed from the vacuum chamber and placed inside a large water tank equipped with scales for weighing thesample under water. underwater. While completely submerge
18、d, the bag is cut open by scissors to allow the water to enter the bag.Since the sample is under complete vacuum, water will be forced around all the accessible areas of the sample. The difference inweight in air and suspended weight in water will provide the sample volume after correcting for the b
19、ag influence. The dry weightand the volume can be used to calculate the maximum specific gravity of the sample. This method is a rapid technique fordetermination of maximum specific gravity that minimizes the exposure of asphalt mixture samples to water during testing andreduces the chance of water
20、absorption.NOTE 1For porous aggregates, if water absorption correction is not performed on the maximum specific gravities obtained using this test method,the results may be higher than the results obtained by Test Method D2041/D2041M. Without aggregate water absorption correction, air voids calculat
21、edbased on these results may be higher.5. Significance and Use5.1 The maximum specific gravities and densities of asphalt mixtures are intrinsic properties whose values are influenced bythe composition of the mixture in terms of types and amounts of aggregates and asphalt materials.5.1.1 They are us
22、ed to calculate values for percent air voids in compacted asphalt mixtures.5.1.2 They provide target values for the compaction of asphalt mixtures.5.1.3 They are essential when calculating the amount of asphalt binder absorbed by the internal porosity of the individualaggregate particles in an aspha
23、lt mixture.NOTE 2The 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 capab
24、leof competent 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 similarac
25、ceptable guideline provides a means of evaluating and controlling some of those factors.6. Apparatus6.1 Balance, with ample capacity, and with sufficient sensitivity to enable maximum specific gravity of specimens to becalculated to at least four significant figures, that is, to at least three decim
26、al places. It shall be equipped with a suitable apparatusto permit weighing the specimen while it is suspended in water. The suspension wire attached to the scales should break the surfaceof the water at a single point and should have a maximum diameter of 3 mm 0.125 in. The balance shall conform to
27、 Guide D4753as a class GP2 balance.NOTE 3Since there are no more significant figures in the quotient (maximum specific gravity) than appear in either the dividend (the mass of thespecimen in air) or in the divisor (the volume of the specimen, obtained from the difference in mass of the specimen in a
28、ir and in water), this means thatthe balance must have a sensitivity capable of providing both mass and volume values to at least four figures. For example, a sensitivity of 0.1 g 0.00022lb would provide four significant figures for the determination of a mass in the range from 130.0 to 999.9 g 0.29
29、 to 2.20 lb when the specific gravityis 2.300.6.2 Water Bath, with minimum dimensions (Length(length Widthwidth Depth)depth) of 610 by 460 by 460 mm 24 by 18by 18 in. or a cylindrical container with a minimum diameter of 460 mm 18 in. and minimum depth of 460 mm 18 in., forcompletely submerging the
30、specimen in water while suspended.NOTE 4Setting the water tank at waist level will enable the user to conduct this test while standing and will significantly simplify the weighingoperations.6.3 Vacuum Chamber,3 with a 0.93 kW 1.25 hp 0.93-kW 1.25-hp pump capable of evacuating a sealed and enclosed c
31、hamberto 5.6 mm Hg 6 Torr. The chamber shall be large enough to seal samples as large as 2200 g 4.85 lb. The device shallautomatically seal the plastic bag and exhaust air back into the chamber in a controlled manner to ensure proper conformance ofthe plastic to the asphalt mixture. The air exhaust
32、and vacuum operation time should be calibrated at the factory prior to initialuse. The air exhaust system should be calibrated to bring the chamber to atmospheric pressure in 80 to 150 s, after the completionof the vacuum operation. The vacuum system should be provided with a latch to control the ch
33、amber door opening.6.4 Absolute Vacuum Measurement Gauge, independent of the vacuum sealing device whichdevice, that may be placed directlyinside the chamber to verify vacuum performance and the chamber door sealing condition of the unit. The gauge shall be capableof reading pressure to 3 mm Hg 3 To
34、rr.3 The sole source of supply of the apparatus and the method known to the committee at this time is InstroTek, Inc., Raleigh, NC. If you are aware of alternative suppliers,please provide this information to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the res
35、ponsible technical committee,1 which youmay attend.D6857/D6857M 1826.5 Plastic Bags, consisting of inner plastic bag (internal bag) having random channels built into one side of the bag, withminimum and maximum bag opening sizes of 305 mm 12 in. and 340 mm 13.5 in., respectively, and outer plastic b
36、ag (externalbag) with minimum and maximum opening sizes of 375368 mm 14.7514.50 in. and 394 mm 15.5 in., respectively. The bagsshall be of plastic material that will not adhere to asphalt film, is puncture resistant, and is impermeable to air. Each bag shall havea minimum thickness of 0.1000.127 mm
37、0.0040.005 in. and maximum thickness of 0.1520.178 mm 0.0060.007 in. Thecombined apparent specific gravity of the two bags shall be provided by the manufacturer.NOTE 5Protect the plastic bags during storage. Rough handling, storing in close proximity to sharp objects, near aggregates, or inside draw
38、ers willdamage the plastic bags. Refer to the manufacturers procedures for safe handling and storage of bags.6.6 Holder, for water displacement of the sample having no sharp edges.6.7 Filler Plates, to position the sample and the bags in the same plane as the sealing bar.6.8 Bag-Cutting Knife, or sc
39、issors.6.9 Thermometric Device, a temperature-measuring temperature measuring device readable to 0.5 C 1 F and accurate to0.3 C 0.5 F for monitoring the temperature of the water bath.6.10 Laboratory Oven, capable of heating the asphalt sample to 110 6 5 C 230 6 9 F7. Sampling7.1 Obtain the sample in
40、 accordance with Practice D979/D979M.7.2 The size of the sample shall conform to the following requirements. Samples larger than 2200 g 4.85 lb may be tested in1500 to 2000 g 3.31 to 4.41 lb portions at a time.Size of Largest Particle ofAggregate in Mixture, mm in.Minimum Sample Size,g50.0 2 600013.
41、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 asphalt mixture by hand, taking care to avoid fracturing the aggregate, so that theparticles of the fine aggregate portion are not larger
42、than 6.3 mm 14 in. If a sample of asphalt mixture is not sufficiently soft tobe separated manually, place it in a flat pan and warm it in an oven until it can be separated as described.8.2 Unless the asphalt mixture has been prepared in a laboratory using oven-dryoven-dried aggregates, oven dry the
43、sample toa constant mass at a temperature of 110 6 5 C 230 6 9 F. Other methods of drying can be used as long as the sample achievesa constant mass (mass repeats within 0.1 %). This drying, and any required warming for particle separation as described in 8.1,should be combined as a single operation
44、to minimize reheating effects.8.3 Cool the sample to room temperature and record the weight. (Refer to Column B of the data collection table. See Table X1.1in the Appendix.)8.4 Set the vacuum sealing machine according to the manufacturers recommendation to create 99 % of absolute vacuum fora minimum
45、 of 5 min inside the chamber.NOTE 6For asphalt mixtures that contain polymers, follow the manufacturers recommendations.8.5 If after examining the external bag there are no punctures or cuts, weigh one channel (internal) and one examined nonchannel non-channel (external) bag.8.6 Record the combined
46、weight of the bags in Column A of the attached data collection table.8.7 Place the sample in the internal bag. Ensure that no sample is lost during this transfer.8.8 Place the empty external bag inside the vacuum chamber.8.9 Place the internal bag containing the sample with the channel side (rough s
47、ide) down into the external bag. The rough sideis placed under the sample to protect against trapped air and to help in the evacuation of the air from the bag.8.10 Spread the sample so that it is evenly distributed within the internal bag. Do not spread the sample by squeezing down onthe sample from
48、 outside the bag.8.11 Push in the opening of the internal bag away from the opening of the external bag to prevent the opening of the internalbag from being sealed. Make sure that the opening of the internal bag is flat and that the opening is not restricted by a fold in thebag.D6857/D6857M 1838.12
49、Place the opening of the external bag over the seal bar, making 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 the chamber and the plastic bag. Follow the manufacturersrecommendations for proper machine settings and time required for the vacuum cycle. The vacuum chamber shall automaticallyseal the bag once the air is removed.8.15 Exhaust air into the chamber until the ch
