1、Designation:D726321Standard Test Methods forLaboratory Determination of Density and Unit Weight of SoilSpecimens1This standard is issued under the fixed designation D7263;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of la
2、st 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 These test methods describe two ways of determiningthe total/moist/bulk density,dry density,and dry unit weight ofintact,dis
3、turbed,remolded,and reconstituted(compacted)soilspecimens(Note 1).Intact specimens may be obtained fromthin-walled sampling tubes,block samples,or clods.Speci-mens that are remolded by dynamic or static compactionprocedures are also measured by these methods.These meth-ods apply to soils that will r
4、etain their shape during themeasurement process and may also apply to other materialssuch as soil-cement,soil-lime,soil-bentonite or solidifiedsoil-bentonite-cement slurries.It is common for the density tobe less than the value based on tube or mold volumes,or of insitu conditions after removal of t
5、he specimen from samplingtubes and compaction molds.This change is due to thespecimen swelling after removal of lateral pressures.NOTE1The adjectives total,moist,wet or bulk are used to representthe density condition.In some professions,such as Soil Science andGeology,the term“bulk density”usually h
6、as the same meaning as drydensity.In the Geotechnical and Civil Engineering professions,thepreferred adjective is total over moist and bulk when referring to the totalmass of partially saturated or saturated soil or rock per unit total volume.For more detailed information regarding the term density,
7、refer toTerminology D653.1.1.1 Method A(Water Displacement)A specimen iscoated in wax and then placed in water to measure the volumeby determining the quantity of water displaced.The densityand unit weight are then calculated based on the mass andvolume measurements.Do not use this method if the spe
8、cimenis susceptible to surface wax intrusion.1.1.2 Method B(Direct Measurement)The dimensionsand mass of a specimen are measured.The density and unitweight are then calculated using these direct measurements.Usually,the specimen has a cylindrical or cuboid shape.Intactand reconstituted/remolded spec
9、imens may be tested by thismethod in conjunction with strength,permeability/hydraulicconductivity(air/water)and compressibility determinations.1.2 UnitsThe values stated in SI units are to be regardedas standard.The values given in parentheses are provided forinformation only and are not considered
10、standard.Reporting oftest results in units other than SI shall not be regarded asnonconformance with this standard.1.2.1 The gravitational system of inch-pound units is usedwhen dealing with inch-pound units.In the system,the pound(lbf)represents a unit of force(weight),while the units formass is sl
11、ugs.The slug unit is not given,unless dynamic(F=ma)calculations are involved.1.2.2 It is common practice in the engineering/constructionprofession to concurrently use pounds to represent both a unitof mass(lbm)and of force(lbf).This practice implicitlycombines two separate systems of units;the absol
12、ute and thegravitational systems.It is scientifically undesirable to com-bine the use of two separate sets of inch-pound units within asingle standard.As stated,this standard includes the gravita-tional system of inch-pound units and does not use/present theslug unit of mass.However,the use of balan
13、ces and scalesrecording pounds of mass(lbm)or recording density in lbm/ft3shall not be regarded as nonconformance with this standard.1.2.3 The terms density and unit weight are often usedinterchangeably.Density is mass per unit volume,whereas unitweight is force per unit volume.In this standard,dens
14、ity isgiven only in SI units.After the density has been determined,the unit weight is calculated in SI or inch-pound units,or both.1.3 All observed and calculated values shall conform to theguidelines for significant digits and rounding established inPractice D6026,unless superseded by this test met
15、hod.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
16、forobtaining the data,special purpose studies,or any consider-ations for the users 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 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is the1These test methods are under the jurisdiction ofA