# ASTM D6683-14

Designation: D6683 − 14Standard Test Method forMeasuring Bulk Density Values of Powders and Other BulkSolids as Function of Compressive Stress1This standard is issued under the fixed designation D6683; 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. Scope*1.1 This test method covers an apparatus and procedure fordetermining a range of bulk densities of powders and otherbulk solids as a function of compressive stress.1.2 This test method should be performed in the laboratoryunder controlled conditions of temperature and humidity.1.3 All observed and calculated values shall conform to theguidelines for significant digits and rounding established inPractice D6026.1.3.1 The procedures used to specify how data are collected/recorded or calculated in this standard are regarded as theindustry standard. In addition, they are representative of thesignificant digits that generally should be retained. The proce-dures used do not consider material variation, purpose forobtaining the data, special purpose studies, or any consider-ations for the user’s objectives, and it is common practice toincrease or reduce significant digits of reported data to becommensurate with these considerations. It is beyond the scopeof this standard to consider significant digits used in analysismethods for engineering design.1.4 Units—The values stated in SI units are to be regardedas standard. No other units of measure are included in thisstandard.1.5 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:2D653 Terminology Relating to Soil, Rock, and ContainedFluidsD2216 Test Methods for Laboratory Determination of Water(Moisture) Content of Soil and Rock by MassD3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD4753 Guide for Evaluating, Selecting, and Specifying Bal-ances and Standard Masses for Use in Soil, Rock, andConstruction Materials TestingD6026 Practice for Using Significant Digits in GeotechnicalData3. Terminology3.1 Definitions—For common definitions of terms in thisstandard, refer to Terminology D653.3.2 Definitions of Terms Specific to This Standard:3.2.1 maximum effective head, n—in powders, height of acolumn of material that has no shear stresses along its verticalwalls. Used in calculation of maximum applied mass, thisvalue can be approximated, for example, by using the height ofthe cylindrical section of the bin to be analyzed, m.3.3 Symbols:3.3.1 Acup—inside cross-sectional area of density cup, m2.3.3.2 AMmax—calculated value of maximum applied mass,kg.3.3.3 Dcup—inside diameter of density cup, m.3.3.4 EHmax—maximum effective head to be applied tomaterial in density cup, m.3.3.5 Mmat’l—mass of material in density cup, kg.3.3.6 Vi—calculated volume of material in density cup at ithconsolidation step, m3.3.3.7 (ρb)approx—approximate value of material’s bulk den-sity used in calculation of maximum applied mass, kg/m3.3.3.8 (ρb)i—calculated bulk density value at ithconsolida-tion step, kg/m3.3.3.9 (ρb)initial—calculated initial bulk density value, kg/m3.3.3.10 σi—calculated compressive stress at ithconsolidationstep, N/m2.1This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.24 on Characterizationand Handling of Powders and Bulk Solids.Current edition approved May 1, 2014. Published June 2014. Originallyapproved in 2001. Last previous edition approved in 2008 as D6683 – 08. DOI:10.1520/D6683-14.2For 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.*A Summary of Changes section appears at the end of this standardCopyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.3.11 σmax—maximum compressive stress to be applied tomaterial in density cup, N/m2.4. Summary of Test Method4.1 Bulk density values are determined by calculating thevolume of a given mass of bulk solid under increasingcompressive stress.5. Significance and Use5.1 The data from this test can be used to estimate the bulkdensity of materials in bins and hoppers and for materialhandling applications such as feeders.5.2 The test results can be greatly affected by the sampleselected for testing. For meaningful results it is necessary toselect a representative sample of the particulate solid withrespect to moisture (water) content, particle-size distributionand temperature. For the tests an appropriate size sampleshould be available, and fresh material should be used for eachindividual test specimen.5.3 Initial bulk density, (ρb)initial, may or may not be used asthe minimum bulk density. This will depend on the materialbeing tested. For example, the two are often close to the samefor coarse (most particles larger than about 6 mm), free-flowingbulk solids, but not for fine, aeratable powders.5.4 Bulk density values may be dependent upon the mag-nitude of the applied mass increments. Traditionally, theapplied mass is doubled for each increment resulting in anapplied mass increment ratio of 1. Smaller than standardincrement ratios may be desirable for materials that are highlysensitive to the applied mass increment ratio. An example ofthe latter is a material whose bulk density increases 10% ormore with each increase in applied mass.5.5 Bulk density values may be dependent upon the durationof each applied mass. Traditionally, the duration is the same foreach increment and equal to 15 s. For some materials, the rateof compression is such that complete compression (no changein volume with time at a given applied compressive stress) willrequire significantly more than 15 s.NOTE 1—The quality of the result produced by this standard isdependent on the competence of personnel performing it, and thesuitability of the equipment and facilities used. Agencies that meet thecriteria of Practice D3740 are generally considered capable of competentand objective testing/sampling/inspection/etc. Users of this standard arecautioned that compliance with Practice D3740 does not in itself assurereliable results. Reliable results depend on many factors; Practice D3740provides a means of evaluating some of those factors. Practice D3740 wasdeveloped for agencies engaged in the testing or inspection (or both) ofsoil and rock. As such it is not totally applicable to agencies performingthis standard. However, users of this standard should recognize that theframework of Practice D3740 is appropriate for evaluating the quality ofan agency performing this standard. Currently there is no known quali-fying national authority that inspects agencies that perform this standard.6. Apparatus6.1 A typical embodiment of the test apparatus is shown inFig. 1.6.2 Balance, having a capacity and readability to determinemass of the specimen and applied masses to four significantdigits in accordance with Table 1 in Guide D4753.6.3 Stand, to support the density cup, and to mount the dialindicator. The stand must be level and securely mounted on avibration free base to support the test apparatus.6.4 Density Cup, with cover to contain the test specimen.Density cup cover has a ball mounted in the center, which actsas a pivot point to ensure that only a vertical force is exerted onthe cover by the applied mass. The density cup is to be acylindrical cup with the minimum cell diameter of 64 mm anda minimum inside height of 21 mm or five times the diameterof the largest particle whichever results in the larger cell height.The ratio of cell diameter-to-height must be at least 3:1.6.5 Applied masses, to be used with the hanger for applyingcompressive stress.6.6 Hanger, to support applied masses and guide load ontothe density cup cover. A thin, short rod extends between thehanger and cover to prevent the hanger from coming in contactwith the density cup or its cover.6.7 Dial or Digital Displacement Indicator, to measurechange in height. Indicator should be able to read in 0.01 mmincrements and apply negligible (if any) force on the testspecimen in the density cup. The spring force from the dialindicator is assumed to be negligible in this test.6.8 Plug, gauge block used to zero the dial indicator. Itslength should be equal to the inside height of the density cup.6.9 Mass Support, to support applied masses as they areadded to compress the material.6.10 Scraper, used to scrape off excess material from top ofcup. It should be straight and flat, with a length in excess of cupdiameter and a width of at least 15 mm.7. Preparation of Apparatus7.1 Check that the balance is set on a sturdy table or bench,level and zeroed, and its calibration/verification sticker iswithin requirements.7.2 Make sure that the density cup and cover are clean andfree of foreign material prior to starting each new test.7.3 Check that the applied masses are clean of foreignmaterial and have a known mass.7.4 Select a minimum of five applied masses to be usedaccording to the following procedure. Additional appliedmasses may be used if more data points are desired or required.7.4.1 Calculate the maximum applied mass, AMmaxbymultiplying the material’s approximate bulk density,(ρb)approx(kg ⁄m3) by maximum effective head to be applied,EHmax(m) times the inside cross-sectional area of the densitycup, Acup.Acup5 π~Dcup!2/4, m2AMmax5 ~ρb!approx~EHmax!~Acup!, kg7.4.2 Alternatively, if the maximum compressive stress tobe applied to the material, σmaxhas been specified, themaximum applied mass, AMmaxis calculated by multiplyingσmaxby the inside cross-sectional area of the density cup, Acup,and then dividing the product by the acceleration of gravity (g),where g = 9.81 m/s2D6683 − 142AMmax5 σmax~Acup!/g, kg7.4.3 Divide the maximum applied mass, AMmax, in halfthen in half again and continue until at least five applied masseshave been identified.8. Procedure8.1 Determine the mass of the density cup and record thisvalue to the nearest 0.1 g or better on a test data sheet as thetare mass.8.2 Determine the mass of the cover and the hanger (thisbecomes the initial mass). Be sure this mass is less than thesmallest applied mass to be used. These are to be recorded tothe nearest 0.1 g or better on a test data sheet, and the total ofthese will be used to calculate the first compressive stress.8.3 Insert the plug (gauge block) inside the density cup.Place the cover on the plug, next place the density cup on thetest stand, and then place the hanger on the cover. Position thedial indicator on the top of the weight hanger, then set the dialindicator to zero. Now carefully lift the plunger of the dialindicator far enough to remove the hanger and slide the densitycup out from under the dial indicator so when the material isput into the density cup, the dial indicator won’t be acciden-tally bumped.8.4 Remove the cover and plug.8.5 Place the test specimen into a mixing bowl, and stir thematerial with a spatula to be assured the material hasn’tagglomerated from transit. Avoid agglomeration and segrega-tion of material.8.6 Carefully spoon the material into the density cup asloosely as possible to the point of overflowing. Scrape off allexcess material using a straight flat scraper. The angle of thescraper as it is drawn across the density cup should be such thatit does not compress the material in the cup. Allow the testspecimen to set for approximately one minute. If it settlesbelow the top of the density cup add additional material tobring the level above the cover and scrape again. Determine themass of the density cup again with the material in the cup. Becareful not to spill any material. Record this value to thenearest 0.1 g or better on the test data sheet.8.7 Place the density cup back on the stand, then carefullyplace the cover so it is centered on the density cup. Place thecentering rod of the hanger over the ball which is mounted tothe center of the cover, and is used as a pivot for the weighthanger. Slowly lift the plunger of the dial indicator, and slidethe cup, cover and hanger under the plunger.Allow the plungerto come down and rest on the hanger. Record the change inheight indicated by the dial indicator to the nearest 0.01 mm onthe test data sheet.1. Stand 5. Dial indicator2. Density cup 6. Dial indicator holder3. Cover 7. Applied masses4. Hanger 8. SupportFIG. 1 Test ApparatusD6683 − 1438.8 Hang the mass support on the bottom of the hanger.Record the change in height due to this additional mass to thenearest 0.01 mm on the test data sheet.8.9 Record the change in height to the nearest 0.01 mm witheach applied mass that is added. Allow 15 s between eachchange in applied mass or until there is no noticeable change inheight, as indicated by the dial indicator.NOTE 2—At the completion of the test, visually inspect the cover’sposition with respect to the density cup. If it is visibly tilted, the test is notvalid and should be repeated, paying particular attention to proceduresteps 8.5 and 8.6. Tilting of the lid is most often caused by non-uniforminitial bulk density in the density cup.9. Calculation9.1 Determine the mass of the material in the density cup,Mmat’l(kg) by subtracting the mass of the density cup from thevalue obtained of the density cup with material in it. This massis in kg.9.2 Determine the initial bulk density, (ρb)initial(kg ⁄m3)bydividing the mass of material in the density cup, Mmat’l(kg) bythe volume of the cup determined by multiplying the insidecross-sectional area of the density cup, Acup, by the height ofthe cup.9.3 Determine the force (N) applied by the cover, hangerand mass support by multiplying the sum of these masses (kg)by acceleration of gravity (g), where g = 9.81 m/s2.9.4 Determine the force (N) applied by each applied mass(kg) by multiplying it by acceleration of gravity (g) where g =9.81 m/s2.9.5 Determine the compressive stress (N/m2) correspondingto each force (N) by dividing the calculated force by the insidecross-sectional area of the density cup, Acup(m2).9.6 For each consolidation step, sum the compressive stress(N/m2) caused by the cover, hanger and mass support with thatcaused by the sum of the applied masses. This is σi(N ⁄m2).9.7 For each consolidation step, determine the volume ofmaterial in the density cup (m3) by subtracting the change inheight of the dial indicator (m) from the plug (gauge block)height