1、Designation: D1883 14Standard 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 re
2、vision. 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 determinat
3、ion of the Cali-fornia Bearing Ratio (CBR) of pavement subgrade, subbase,and base course materials from laboratory compacted speci-mens. The test method is primarily intended for, but not limitedto, evaluating the strength of materials having maximumparticle size less than34 in. (19 mm).1.2 When mat
4、erials having a maximum particle size greaterthan34 in. (19 mm) are to be tested, this test method providesfor modifying the gradation of the material so that the materialused for tests all passes the34-in. (19-mm) sieve while the totalgravel (3 in. (75 mm) to plus No. 4 (4.75 mm) fractionremains th
5、e same. While traditionally this method of specimenpreparation has been used to avoid the error inherent in testingmaterials containing large particles in the CBR test apparatus,the modified material may have significantly different strengthproperties than the original material. However, a large exp
6、eri-ence database has been developed using this 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 percentag
7、es of particles retainedon the No. 4 (4.75 mm) sieve 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 ofw
8、ater content from a specified compaction test and a specifieddry unit weight. The dry unit weight is usually given as apercentage of maximum dry unit weight determined by TestMethods D698 or D1557.1.5 The client requesting the test may specify the watercontent or range of water contents and the dry
9、unit weight forwhich the CBR is desired.1.6 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.1.7 For the determination of CBR of field in-placematerials, s
10、ee Test Method D4429.1.8 UnitsThe values stated in inch-pound units are to beregarded as standard. The SI units given in parentheses aremathematical conversions, which are provided for informationpurposes only and are not considered standard. Reporting oftest results in units other than inch-pound u
11、nits shall not beregarded as nonconformance with this test method.1.8.1 The gravitational system of inch-pound units is usedwhen dealing 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 dyna
12、mic (F = ma)calculations are involved.1.8.2 The slug unit of mass is almost never used incommercial practice; that is, density, balances, etc. Therefore,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/pr
13、esented in parentheses.1.8.3 It is common practice in the engineering/constructionprofession, in the United States, to concurrently use pounds torepresent both a unit of mass (lbm) and of force (lbf). Thisimplicitly combines two separate systems of units; that is, theabsolute system and the gravitat
14、ional system. It is scientificallyundesirable to combine the use of two separate sets ofinchpound units within a single standard. As stated, thisstandard includes the gravitational system of inch-pound unitsand does not use/present the slug unit for mass. However, theuse of balances or scales record
15、ing pounds of mass (lbm) orrecording density in lbm/ft3shall not be regarded as noncon-formance with this standard.1.8.4 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, density is1This tes
16、t method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.05 on Strength andCompressibility of Soils.Current edition approved Dec. 1, 2014. Published January 2015. Originallyapproved in 1961. Last previous edition approved in 2007 as
17、 D1883 072. DOI:10.1520/D1883-14.*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 States1given only in SI units. After the density has been determined,the unit weight is calcula
18、ted in SI or inch-pound units, or both.1.9 All observed and calculated values shall conform to theguidelines for significant digits and rounding established inPractice D6026.1.9.1 The procedures used to specify how data are collected/recorded or calculated in this standard are regarded as theindustr
19、y 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 users objectives, and it is common practice toin
20、crease or reduce significant digits or reported data to becommensurate with these considerations. It is beyond the scopeof this standard to consider significant digits used in analyticalmethods for engineering design.1.10 This standard does not purport to address all of thesafety concerns, if any, a
21、ssociated 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:2D422 Test Method for Particle-Size Analysis of SoilsD6
22、53 Terminology Relating to Soil, Rock, and ContainedFluidsD698 Test Methods for Laboratory Compaction Character-istics of Soil Using Standard Effort (12 400 ft-lbf/ft3(600kN-m/m3)D1557 Test Methods for Laboratory Compaction Character-istics of Soil Using Modified Effort (56,000 ft-lbf/ft3(2,700 kN-m
23、/m3)D2168 Practices for Calibration of Laboratory Mechanical-Rammer Soil CompactorsD2216 Test Methods for Laboratory Determination of Water(Moisture) Content of Soil and Rock by MassD2487 Practice for Classification of Soils for EngineeringPurposes (Unified Soil Classification System)D2488 Practice
24、for Description and Identification of Soils(Visual-Manual Procedure)D3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD4318 Test Methods for Liquid Limit, Plastic Limit, andPlasticity Index of SoilsD
25、4429 Test Method for CBR (California Bearing Ratio) ofSoils in PlaceD4753 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 GeotechnicalDataE11 Specification for Woven W
26、ire Test Sieve Cloth and TestSieves3. Terminology3.1 Definitions:3.1.1 For common definitions of terms in this standard, referto Terminology D653.3.2 Definitions of Terms Specific to This Standard:3.2.1 water content of the compaction specimen, wiwatercontent in percent of material used to compact t
27、he testspecimen.3.2.2 water content top 1 in. (25.4-mm) after soakingwswater content in percent of upper 1 in. (25.4 mm) ofmaterial removed from the compacted specimen after soakingand penetration.3.2.3 water content after testing, wfwater content in per-cent of the compacted specimen after soaking
28、and finalpenetration; does not include material described in 3.2.2.3.2.4 dry density as compacted and before soaking, didrydensity of the as compacted test specimen using the measuredwet mass and calculating the dry mass using the water contentdefined in 3.2.1.4. Summary of Test Method4.1 The Califo
29、rnia Bearing Ratio (CBR) test is used inevaluating subgrade, subbase and base materials as an aid tothe design of pavements. The laboratory test uses a circularpiston to penetrate material compacted in a mold at a constantrate of penetration. The CBR is expressed as the ratio of theunit load on the
30、piston required to penetrate 0.1 in. (2.5 mm)and 0.2 in (5.1 mm) of the test material to the unit load requiredto penetrate a standard material of well-graded crushed stone.4.2 This test method is used to determine the CBR of amaterial compacted in a specified mold. It is incumbent on therequesting
31、client to specify the scope of testing to satisfy theclients protocol or specific design requirements. Possiblescope of testing includes:4.2.1 CBR penetration tests can be performed on each pointof a compaction test performed in accordance with Method Cof D698 or D1557. The CBR mold with the spacer
32、diskspecified in this standard has the same internal dimensions asa 6.000-in. (152.4-mm) diameter compaction mold.4.2.2 Another alternative is for the CBR test to be per-formed on material compacted to a specific water content anddensity. Alternatively, a water content range may be stated forone or
33、more density values and will often require a series ofspecimens prepared using two or three compactive efforts forthe specified water content or over the range of water contentsrequested. The compactive efforts are achieved by followingprocedures of D698 or D1557 but varying the blows per layerto pr
34、oduce densities above and below the desired density.5. Significance and Use5.1 This test method is used to evaluate the potentialstrength of subgrade, subbase, and base course materials,including recycled materials for use in the design of road and2For referenced ASTM standards, visit the ASTM websi
35、te, 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.D1883 142airfield pavements. The CBR value obtained in this test formsan integral part of several flexible paveme
36、nt design methods.5.2 For applications where the effect of compaction watercontent on CBR is small, such as cohesionless, coarse-grainedmaterials, or where an allowance is made for the effect ofdiffering compaction water contents in the design procedure,the CBR may be determined at the optimum water
37、 content ofa specified compaction effort. The specified dry unit weight isnormally the minimum percent compaction allowed by theusing clients field compaction specification.5.3 For applications where the effect of compaction watercontent on CBR is unknown or where it is desired to accountfor its eff
38、ect, the CBR is determined for a range of watercontents, usually the range of water content permitted for fieldcompaction by using the clients protocol or specification forfield compaction.5.4 The criteria for test specimen preparation of self-cementing (and other) materials which gain strength with
39、 timemust be based on a geotechnical engineering evaluation. Asdirected by the client, self-cementing materials shall be prop-erly cured until bearing ratios representing long term serviceconditions can be measured.NOTE 1The quality of the results produced by this standard isdependent on the compete
40、nce of the 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
41、D3740 does not in itself ensurereliable results. Reliable results depend on many factors; Practice D3740provides a means of evaluating some of those factors.6. Apparatus6.1 Loading MachineThe loading machine shall beequipped with a movable head or base that travels at a uniform(not pulsating) rate o
42、f 0.05 in. (1.3 mm)/min for use in pushingthe penetration piston into the specimen. The load rate of 0.05in. (1.3 mm)/min shall be maintained within 620% over therange of loads developed during penetration. The minimumcapacity of the loading machine shall be based on the require-ments indicated in T
43、able 1.6.1.1 The machine shall be equipped with a load-indicatingdevice matched to the anticipated maximum penetration load.The load-indicating device shall have a minimum accuracy of:10 lbf (44 N) or less for a 10,000 lbf (44 kN) capacity; 5 lbf (20N) or less for 5,000 lbf (22 kN) and 2 lbf (9 N) o
44、r less for 2,500lbf (11 kN).6.2 Penetration Measuring DeviceThe penetration mea-suring device (such as a mechanical dial indicator or electronicdisplacement transducer) shall be capable of reading to thenearest 0.001 in. (0.025 mm) and provided with appropriatemounting hardware. The mounting assembl
45、y of the deforma-tion measuring device shall be connected to the penetratingpiston and the edge of the mold providing accurate penetrationmeasurements. Mounting the deformation holder assembly to astressed component of the load frame (such as tie rods) willintroduce inaccuracies of penetration measu
46、rements.6.3 MoldThe mold shall be a rigid metal cylinder with aninside diameter of 6.000 6 0.026 in. (152.4 6 0.66 mm) anda height of 7.000 6 0.018 in. (177.8 6 0.46 mm). It shall beprovided with a metal extension collar at least 2.0 in. (50.8mm) in height and a metal base plate having at least twen
47、tyeight116-in. (1.59-mm) diameter holes uniformly spaced overthe plate within the inside circumference of the mold. Whenassembled with the spacer disc placed in the bottom of themold, the mold shall have an internal volume (excludingextension collar) of 0.0750 6 0.0009 ft3(2124 6 25 cm3). Amold asse
48、mbly having the minimum required features is shownin Fig. 1. A calibration procedure shall be used to confirm theactual volume of the mold with the spacer disk inserted.Suitable calibration procedures are contained in Test MethodsD698 and D1557.6.4 Spacer DiskA circular metal spacer disc (see Fig. 1
49、)having a minimum outside diameter of 51516 in. (150.8 mm)but no greater than will allow the spacer disc to easily slip intothe mold. The spacer disc shall be 2.416 6 0.005 in. (61.37 60.13 mm) in height.6.5 RammerA rammer as specified in either Test MethodsD698 or D1557 except that if a mechanical rammer is used itmust be equipped with a circular foot, and when so equipped,must provide a means for distributing the rammer blowsuniformly over the surface of the soil when compacting in a6.000-in. (152.4-mm) diameter mold. The mechanical rammermust be calibrate
