1、Designation:D188321Standard Test Method forCalifornia Bearing Ratio(CBR)of Laboratory-CompactedSoils1This standard is issued under the fixed designation D1883;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.
2、A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope*1.1 This test method covers the determination of the Ca
3、li-fornia Bearing Ratio(CBR)of laboratory compacted speci-mens.The test method is primarily intended for,but not limitedto,evaluating the strength of materials having maximumparticle size less than34in.(19 mm).1.2 When materials having a maximum particle size greaterthan34in.(19 mm)are to be tested,
4、this test method providesfor modifying the gradation of the material so that the materialused for testing all passes the34-in.(19-mm)sieve while thetotal gravel fraction(material passing the 3-in.(75-mm)sieveand retained on the No.4(4.75-mm)sieve)remains the same.While traditionally this method of s
5、pecimen preparation hasbeen used to avoid the error inherent in testing materialscontaining large particles in the CBR test apparatus,themodified material may have significantly different strengthproperties than the original material.However,a large experi-ence database has been developed using this
6、 test method formaterials for which the gradation has been modified,andsatisfactory design methods are in use based on the results oftests using this procedure.1.3 Past practice has shown that CBR results for thosematerials having substantial percentages of particles retainedon the No.4(4.75 mm)siev
7、e are more variable than for finermaterials.Consequently,more trials may be required for thesematerials to establish a reliable CBR.1.4 This test method provides for the determination of theCBR of a material at optimum water content or a range ofwater contents from a specified compaction test and a
8、specifieddry unit weight.The dry unit weight is usually given as apercentage of maximum dry unit weight determined by TestMethods D698 or D1557.1.4.1 The client requesting the CBR test may specify thewater content or range of water contents and/or the dry unitweight for which the CBR is desired.1.5
9、Unless specified otherwise by the requesting client,orunless it has been shown to have no effect on test results for thematerial being tested,all specimens shall be soaked prior topenetration.1.6 UnitsThe values stated in inch-pound units are to beregarded as standard.The SI units given in parenthes
10、es aremathematical conversions,which are provided for informationpurposes only and are not considered standard.Reporting oftest results in units other than inch-pound units shall not beregarded as nonconformance with this test method.1.6.1 The gravitational system of inch-pound units is usedwhen dea
11、ling with inch-pound units.In this system,the pound(lbf)represents a unit of force(weight),while the unit for massis slugs.The slug unit is not given,unless dynamic(F=ma)calculations are involved.1.6.2 The slug unit of mass is almost never used incommercial practice;that is,density,balances,etc.Ther
12、efore,the standard unit for mass in this standard is either kilogram(kg)or gram(g),or both.Also,the equivalent inch-pound unit(slug)is not given/presented in parentheses.1.6.3 It is common practice in the engineering/constructionprofession,in the United States,to concurrently use pounds torepresent
13、both a unit of mass(lbm)and of force(lbf).Thisimplicitly combines two separate systems of units;that is,theabsolute system and the gravitational system.It is scientificallyundesirable to combine the use of two separate sets ofinch-pound units within a single standard.As stated,thisstandard includes
14、the gravitational system of inch-pound unitsand does not use/present the slug unit for mass.However,theuse of balances or scales recording pounds of mass(lbm)orrecording density in lbm/ft3shall not be regarded as noncon-formance with this standard.1.6.4 The terms density and unit weight are often us
15、edinterchangeably.Density is mass per unit volume whereas unitweight is force per unit volume.In this standard,density isgiven only in SI units.After the density has been determined,the unit weight is calculated in SI or inch-pound units,or both.1This test method is under the jurisdiction ofASTM Com
16、mittee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.05 on Strength andCompressibility of Soils.Current edition approved Nov.15,2021.Published December 2021.Originallyapproved in 1961.Last previous edition approved in 2016 as D1883 16.DOI:10.1520/D1883-21.*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 StatesThis international standard was developed in
