# ASTM D6995-05 (Reapproved 2013)

Designation: D6995 − 05 (Reapproved 2013)Standard Test Method forDetermining Field VMA based on the Maximum SpecificGravity of the Mix (Gmm)1This standard is issued under the fixed designation D6995; the number immediately following the designation indicates the year oforiginal adoption or, 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 is intended to be used for a rapid fielddetermination of voids in mineral aggregate (VMA) of hot mixasphalt (HMA). It provides equations for calculating the VMAbased on the asphalt content of the mix and its maximumspecific gravity (Gmm). It is intended that this should be usedfor the rapid “field” determination of VMA during QualityControl (QC) operations at HMA plants, particularly where thespecific gravity of the aggregate is highly variable.1.2 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 regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C127 Test Method for Density, Relative Density (SpecificGravity), and Absorption of Coarse AggregateC128 Test Method for Density, Relative Density (SpecificGravity), and Absorption of Fine AggregateD70 Test Method for Density of Semi-Solid BituminousMaterials (Pycnometer Method)D854 Test Methods for Specific Gravity of Soil Solids byWater PycnometerD2041 Test Method for Theoretical Maximum SpecificGravity and Density of Bituminous Paving MixturesD2172 Test Methods for Quantitative Extraction of BitumenFrom Bituminous Paving MixturesD2726 Test Method for Bulk Specific Gravity and Densityof Non-Absorptive Compacted Bituminous MixturesD6307 Test Method for Asphalt Content of Hot-Mix Asphaltby Ignition Method3. Summary of Test Method3.1 The percent of (field) VMA in the mix can be calculatedby means of equations in which measured values for thetheoretical maximum specific gravity, the asphalt content, thespecific gravity of the asphalt, and the average bulk specificgravity of the total aggregate and the compacted mix areknown.4. Significance and Use4.1 Various users desire indication of compliance withVMA specifications for hot mix asphalt (HMA) during pro-duction.4.2 The standard practice for determining VMA requiresthat the bulk specific gravity of the aggregate components bedetermined. This is a very time consuming test, which is notsuitable for routine QC procedures.4.3 When an aggregate source used in the mix has a highlyvariable bulk specific gravity and a reference average bulkspecific gravity (Gsb) (for example, as established in the mixdesign) is used to calculate VMA during HMA production,erroneous values may occur.4.4 The test for maximum specific gravity of the mix (Gmm)is a routine QC test at HMA plants. The effective specificgravity of the aggregate components (Gse) can be easilycalculated from this test. However the Gsedoes not take intoaccount the amount of asphalt absorbed, which is required foraccurate VMAdetermination. This method provides a means tocorrect the Gseto account for the average absorbed asphalt.This procedure should not be used if the percent waterabsorption of the total (combined) aggregates varies betweenfour tests, randomly obtained over a 30 day period, by morethan 0.4 %.5. Procedure5.1 Determine the percent of field VMAin a compacted mixsample by first obtaining the following information and thencalculating the value.5.2 Tests Run During the HMA Mix Design Procedure5.2.1 Test Method C127, C128, and D854—Determine theaverage bulk specific gravity (Gsb) of the fine and coarseaggregates, and mineral filler if applicable. Once this value is1This 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 edition approved June 1, 2013. Published September 2013. Originallyapproved in 2005. Last previous edition approved in 2005 as D6995 – 05. DOI:10.1520/D6995-05R13.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at service@astm.org. For Annual Book of ASTMStandards volume information, refer to the standard’s Document Summary page onthe ASTM website.Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1determined it should be used in the calculations in section 6.1.1until a change in the plant produced mix occurs.NOTE 1—It is recommended that a minimum of three sets of tests (onefor each aggregate) should be averaged to establish this bulk specificgravity.5.2.2 Use the percent by weight of each aggregate estab-lished in the mix design in the calculation in section 6.1.1.Ifthe percent of individual aggregates in the mix is changedduring production a new Gsb(comb) should be calculated persection 6.1.1, using the new percentages.5.2.3 Test Method D70—Determine the specific gravity ofthe asphalt binder (Gb)5.2.4 Determine the bulk specific gravity of the combinedaggregates in the mix (Gsb(comb) in accordance with theformula in section 6.1.1, using the values established above.5.2.5 Prepare a lab mix according to the mix design, atoptimum asphalt content. Use this mix to establish a correctionfactor (Cf) for asphalt absorption, with the formula in section6.1.3. It is intended that this Cfwill remain constant untilsubsequent testing indicates a change is appropriate.NOTE 2—It is recommended that a corresponding lab mix be preparedand tested in accordance with Note 1. The correction factors that aredetermined should be averaged and used in section 5.3.5.5.3 QC Tests Run During HMA Production5.3.1 Test method D6307 or D2172—Determine the percentof asphalt binder in the plant produced mix.5.3.2 Test method D2726—Determine the bulk specificgravity of the compacted mix (Gmb).5.3.3 Test Method D2041—Determine the maximum spe-cific gravity of the mix (Gmm). An appropriate mix short termaging procedure must be defined by the user of this standard.NOTE 3—Since the amount of asphalt absorbed is affected by the lengthof the short term aging of the mix, it is recommended that the sameprocedure used in the mix design also be used in the field, unless it can bedemonstrated that another aging period is more appropriate.5.3.4 Determine the effective specific gravity (Gse)oftheplant mix sample in accordance with the formula in section6.1.2, using the appropriately adjusted values from sections5.2.3, 5.3.1, and 5.3.3.5.3.5 Use the correction factor (Cf) established in the mixdesign (see section 5.2.5) to determine the field VMA. Thisfactor may need periodic adjustment based on plant production(see sections 5.2.2 and Note 4). If the (Cf) varies by more than10 %, it should be re-verified in accordance with section 5.2.5.NOTE 4—Verification testing – Since this method depends on theasphalt absorption remaining constant, it is recommended that the bulkspecific gravity of each aggregate be tested approximately once per monthduring production and the Gsb(comb) revised if there is a change of0.015 in any aggregate Gsb. A corresponding sample of plant mix shouldbe obtained in conjunction with this testing and the Cfverified.5.3.6 Determine the field VMA in accordance with section6.2 using the values from section 5.3.2, 5.3.4, and 5.3.5.6. Calculation6.1 Determine the laboratory correction factor as follows:6.1.1 Determine the average bulk specific gravity of thecombined aggregate (Gsb) as follows:Gsbscombd 5100% of aggregate #1bulk specific gravitysGsb1d1% of aggregate #2bulk specific gravitysGsb2d1{(1)6.1.2 Determine the effective specific gravity (Gse)oftheaggregate in the mix as follows:Gse5100.0 2 % asphalt binder100.0Gmm2% asphalt binderspecific gravity of asphalt ~Gb!(2)6.1.3 Establish a correction factor for asphalt absorption asfollows :Cf5 Gse2 Gsb ~comb!(3)6.2 Determine the field VMA as follows:VMA~field!5 100.0 2 @~Gmb*Ps!/~Gse2 Cf!# (4)Where:Gmb= Bulk specific gravity of compacted mixPs= Percent aggregate in the mix (100.0 - % asphaltbinder)Gse= Effective specific gravity of the aggregateCf= Correction factor for asphalt absorptionNOTE 5—The percent aggregate in the mix should be based on actualasphalt content of the mix as determined in section 5.NOTE 6—The field VMAmay yield a different value than the traditionalmethod of calculation described in sec.4.10 of the Asphalt Institute MS-2.7. Report7.1 Report the test values as follows:7.1.1 Report the field VMA to the nearest 0.1 %7.1.2 Report the Gse, individual Gsb,Gsb(comb), Gb,Gmm,and Cfto the nearest 0.0017.1.3 Report the percent asphalt binder to the nearest 0.1 %8. Precision and Bias8.1 Precision8.1.1 Single Operator Precision—Method to determine % AC Gsewithin lab STDTest Method D2172 0.008Test Method D6307 0.0148.1.2 Multilaboratory PrecisionMethod to determine % AC Gsebetween lab STDTest Method D2172 0.024Test Method D6307 0.026NOTE 7—The precision estimates were obtained from a Monte CarloSimulation of input data used to calculated the Gse.8.2 BiasNo information can be presented on the bias of the procedurebecause no material having an accepted reference value isavailable.9. Keywords9.1 HMA; Field VMA; QCD6995 − 05 (2013)2ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. 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