1、Designation: D 7370 08Standard Test Method forDetermination of Relative Density and Absorption of Fine,Coarse and Blended Aggregate Using Combined VacuumSaturation and Rapid Submersion1This standard is issued under the fixed designation D 7370; the number immediately following the designation indica
2、tes 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 standard covers the determination of re
3、lative den-sity and absorption of fine aggregates by Method A and coarseand blended aggregates by Method B.1.2 The values are stated in SI units and are regarded as thestandard units.1.3 A multi-laboratory precision and bias statement forcoarse and combined aggregate tests in this standard has notbe
4、en developed at this time. Therefore, this standard should notbe used for acceptance or rejection of coarse and combinedaggregate materials for purchasing purposes.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the
5、 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:2C 29/C 29M Test Method for Bulk Density (“Unit Weight”)and Voids in AggregateC 127 Test Method for Density,
6、Relative Density (SpecificGravity), and Absorption of Coarse AggregateC 128 Test Method for Density, Relative Density (SpecificGravity), and Absorption of Fine AggregateC 136 Test Method for Sieve Analysis of Fine and CoarseAggregatesC 670 Practice for Preparing Precision and Bias Statementsfor Test
7、 Methods for Construction MaterialsC 702 Practice for Reducing Samples of Aggregate toTesting SizeD75 Practice for Sampling AggregatesD 4753 Guide for Evaluating, Selecting, and SpecifyingBalances and Standard Masses for Use in Soil, Rock, andConstruction Materials TestingD 3666 Specification for Mi
8、nimum Requirements forAgen-cies Testing and Inspecting Road and Paving MaterialsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Summary of Test Method3.1 Sufficient aggregate sample is dried to constant mass.For each test two representative dry agg
9、regate samples of thesame material are selected for testing. One sample is evacuatedin a vacuum chamber inside a plastic bag and opened underwater for rapid saturation of the aggregate. The dry mass andsubmerged mass of the sample is used for calculation ofapparent relative density. The second sampl
10、e of the sameaggregate is tested in a known volume metal pycnometer. Theknown mass of the pycnometer with water, mass of the dryaggregate and mass of the aggregate and pycnometer filledwith water is used for calculation of unsaturated density. Theresults from the two samples tested are then used to
11、calculateabsorption, and relative density (OD).3.2 This test can be completed in less than 30 minutes andcan be used for rapid determination of aggregate properties inconstruction testing laboratories.3.3 This test can be performed on fine, coarse and blended(combined) aggregates by using appropriat
12、e plastic bag andpycnometer sizes.4. Significance and Use4.1 Relative density (specific gravity) is the characteristicgenerally used for calculation of the volume occupied by theaggregate in various mixtures containing aggregate, includingPortland cement concrete, bituminous concrete, and othermixtu
13、res that are proportioned or analyzed on an absolute1This test method is under the jurisdiction of ASTM Committee D04 on Roadand Paving Materials and is the direct responsibility of Subcommittee D04.51 onAggregate Tests.Current edition approved July 15, 2008. Published August 2008.2For referenced AS
14、TM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshoh
15、ocken, PA 19428-2959, United States.volume basis. Relative density (specific gravity) is also used inthe computation of voids in aggregate in Test Method C 29/C 29M. Relative density (specific gravity) saturated surface dry(SSD) is used if the aggregate is at SSD, that is, if itsabsorption has been
16、satisfied. Conversely, the relative density(specific gravity) oven-dry (OD) is used for computationswhen the aggregate is dry or assumed to be dry.4.2 Apparent density and apparent relative density (apparentspecific gravity) pertain to the solid material making up theconstituent particles not includ
17、ing the pore space within theparticles which is accessible to water.4.3 Absorption values are used to calculate the change in themass of an aggregate due to water absorbed in the pore spaceswithin the constituent particles, when it is deemed that theaggregate has been in contact with water long enou
18、gh to satisfythe absorption potential. The laboratory standard for absorptionis that obtained after submerging dry aggregate for a prescribedperiod of time.NOTE 1There are other test methods that have been used and continueto be used to determine these aggregate properties: C 127 and C 128. Thistest
19、 method may result in values for these properties that are close to ordivergent from values from other test methods.NOTE 2The quality of the results produced by this standard aredependant upon the competence of the personnel performing the proce-dure and the capability, calibration, and the maintena
20、nce of the equipmentused. Agencies that meet the criteria of Practice D 3666 are generallyconsidered capable of competent and objective testing / sampling /inspection / etc. Users of this standard are cautioned that compliance withPractice D 3666 alone does not completely assure reliable results. Re
21、liableresults depend on many factors: following the suggestions of PracticeD 3666 or similar acceptable guideline provides a means of evaluating andcontrolling some of those factors.5. Apparatus5.1 Balance, a balance that conforms to Guide D 4753. Thebalance shall be sensitive, readable and accurate
22、 to 0.1 g. Thebalance shall be equipped with suitable apparatus for suspend-ing the sample in water.5.2 Water Bath, with minimum dimensions (Length byWidth by Depth) of 610 by 460 by 460 mm (24 by 18 by 18 in.)or a large cylindrical container with a minimum diameter of460 mm and depth of 460 mm (18
23、by 18 in.), for completelysubmerging the sample in water while suspended, equippedwith an overflow outlet for maintaining a constant water leveland means to maintain the water temperature at 25 6 1C (776 2F).NOTE 3It is preferable to keep the water temperature constant byusing a temperature controll
24、ed heater. Also, to reduce the chance for thebag to touch the sides of the water tank, it is preferable to elevate the watertank to a level at which the sample can be placed on the weighingmechanism while the operator is standing up (waist height), and theplacement of the sample and the bag in the w
25、ater tank can easily beinspected.5.3 Sample Holder, for water displacement of the sample,having no sharp edges.5.4 Vacuum Chamber, with a pump capable of evacuating asealed and enclosed chamber to a pressure of 6 mm Hg, whenat sea level. The device shall automatically seal the plastic bagand exhaust
26、 air back into the chamber in a controlled mannerto ensure proper conformance of the plastic to the specimen.The air exhaust and vacuum operation time shall be set at thefactory so that the chamber is brought to atmospheric pressurein 80 to 125 seconds, after the completion of the vacuumoperations.5
27、.5 Vacuum Measurement Gauge, independent of thevacuum sealing device that could be placed directly inside thechamber to verify vacuum performance and the chamber doorsealing condition of the unit. The gauge shall be capable ofreading down to 3 mm Hg and readable to 61mmHg.5.6 Plastic Bags, used with
28、 the vacuum device shall be oneof the two following sizes. The smaller bags shall have aminimum opening of 235 mm (9.25 in.) and maximum openingof 260 mm (10.25 in.) and the larger bags shall have aminimum opening of 375 mm (14.75 in.) and a maximumopening of 394 mm (15.5 in.). The bags shall be of
29、plasticmaterial, shall be puncture resistant, and shall be impermeableto water. The bags shall have a minimum thickness of 0.127mm (0.005 in.). The apparent specific gravity for the bags shallbe provided by the manufacturer.5.7 Small Metal Pycnometer, with 137 6 0.2 mm (5.375 60.008 in.) ID and 89 6
30、 0.40 mm (3.5 6 0.016 in.) height, fortesting fine aggregates. The pycnometer shall be machined tobe smooth on all surfaces. The inside of the lid shall bemachined at a 5 angle to create an inverted conical surface.The pycnometer shall be equipped with a temperature strip toallow the user to monitor
31、 temperature during testing.5.8 Large Metal Pycnometer, with 198 6 0.2 mm (7.776 60.008 in.) ID and 114 6 0.8 mm (4.5 6 0.03 in.) height, fortesting coarse and blended aggregate. The pycnometer shall bemachined to be smooth on all surfaces. The inside of the lidshall be machined at a 5 angle to crea
32、te an inverted conicalsurface. The pycnometer shall be equipped with a temperaturestrip to allow the user to monitor temperature during testing.5.9 Fine Aggregate Fixture, for holding and securing the lidon the small metal pycnometer from lifting during fine aggre-gate tests. The fixture shall be pr
33、ovided with a level indicator.5.10 AccessoriesBag cutting knife or scissors, spraybottle filled with isopropyl alcohol, a bucket large enough toallow the pycnometer to be fully submerged in water, watercontainers to dispense water into pycnometer during testing,syringe with a needle no larger in dia
34、meter than 3 mm (0.125in.), small paint brush and 25 6 5mm(16 0.2 in.) wide metalspatula.5.11 Rubber Sheets, for protecting the plastic bags againstpunctures caused by sharp edges on coarse and blendedaggregate samples. The apparent specific gravity for the rubbersheets shall be provided by the manu
35、facturer.5.12 PC computer, with appropriate software for calculationof the results.6. Verification6.1 System Verification:6.1.1 The vacuum settings of the vacuum chamber shall beverified once every 12 months and after major repairs and aftereach shipment or relocation.6.1.2 Place the gauge inside th
36、e vacuum chamber and recordthe setting, while the vacuum unit is operating. The gaugeD7370082should indicate a pressure of 6 mm Hg (6 TORR) or less. Theunit shall not be used if the gauge reading is above 6 mm Hg(6 TORR).6.1.3 Vacuum gauge used for verification shall be verifiedfor accuracy once eve
37、ry three years.NOTE 4In line vacuum gauges, while capable of indicating vacuumperformance of the pump, are not suitable for use in enclosed vacuumchambers and cannot accurately measure vacuum levels.NOTE 5The worksheet in the appendix is provided as an optional toolto the user for recording of masse
38、s obtained during this test method. Usersmay develop their own worksheet or a computer program for this purpose.6.2 Calibration of the Small Pycnometer:6.2.1 Prior to testing, condition the pycnometer at 25 6 1C(77 6 2F) by placing it inside a bucket of water that ismaintained at 25 6 1C (77 6 2F).
39、Use a level indicator or theprovided level to level the fixture.6.2.2 Remove the pycnometer from the water bucket anddry it with a towel. Place the pycnometer in the fixture andpush it back until it makes contact with the stops.6.2.3 Fill the pycnometer with 25 6 1C (77 6 2F) waterto approximately 1
40、0 mm (0.375 in.) from the top. Using thealcohol spray bottle, spray the surface of the water to removebubbles.6.2.4 Gently place the lid on the pycnometer and close theclamps on the fixture.6.2.5 Using a syringe filled with 25 6 1C (77 6 2F)water, slowly fill the pycnometer through the large fill ho
41、le onthe lid post. Make sure the syringe tip is far enough in thepycnometer to be below the water level. Gentle application inthis step prevents formation of air bubbles inside the pycnom-eter. Fill the pycnometer until water comes out the 3 mm (18in.) hole on the surface of the lid.6.2.6 Wipe any r
42、emaining water from the top of the lid witha towel.6.2.7 Place the entire fixture with the pycnometer on thescale and record the mass.6.2.8 Clean the pycnometer and repeat steps 6.2.1 to 6.2.7two more times and average the calibration masses obtained in6.2.7.6.2.9 If the range for the 3 calibration
43、masses is larger than0.5 g, then the test is not being run correctly. Check to see if thefixture is level. Make certain the water injection with thesyringe is done below the pycnometer water surface and isapplied gently. Check the water temperature. Check the pyc-nometer temperature. Repeat the abov
44、e procedure until youhave three masses that are within 0.5 g range.6.2.10 Re-calibrate the pycnometer for each day of use.6.3 Calibration of the Large Pycnometer:6.3.1 Prior to testing, condition the pycnometer at 25 6 1C(77 6 2F) by placing it inside a bucket of water that ismaintained at 25 6 1C (
45、77 6 2F).6.3.2 Remove the pycnometer from the water bucket anddry it with a towel. Set the pycnometer on a level surface.6.3.3 Fill the pycnometer with 25 6 1C (77 6 2F) waterto approximately 10 mm (0.375 in.) from the top. Using thealcohol spray bottle, spray the surface of the water to removeany a
46、ir bubbles.6.3.4 Gently place the lid on the pycnometer. Using asyringe filled with 25 6 1C (77 6 2F) water, slowly fill thepycnometer through the large fill hole on the lid post. Makesure the syringe tip is far enough in the pycnometer to be belowthe water level. Gentle application in this step pre
47、ventsformation of air bubbles inside the pycnometer. Fill thepycnometer until water comes out the 3 mm (18 in.) hole on thesurface of the lid.6.3.5 Wipe any remaining water from the top of the lid andsides with a towel. Place the pycnometer on the scale andrecord the mass.6.3.6 Clean the pycnometer
48、and repeat steps 6.3.2 to 6.3.5two more times and average the calibration masses obtained in6.3.5.6.3.7 If the range for the 3 calibration masses is larger than1 g, then the test is not being run correctly. Check to see if thefixture is level. Make certain the water injection with thesyringe is done
49、 below the pycnometer water surface and isapplied gently. Check the water temperature. Check the pyc-nometer temperature. Repeat the above procedure until youhave three masses that are within 1 g range.6.3.8 Re-calibrate the pycnometer for each day of use.7. Sampling7.1 Fine Aggregate Samples (Method A):7.1.1 Sampling shall be done in accordance with PracticeD75. For fine aggregate testing thoroughly mix the sample andreduce it to obtain one 1000 6 5 g sample for apparent densityand two 500 6 3 g samples for determination of apparent bulkdensity. For aggrega
