ASTM D1883-2007e1 Standard Test Method for CBR (California Bearing Ratio) of Laboratory-Compacted Soils.pdf

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1、Designation: D 1883 071Standard Test Method forCBR (California Bearing Ratio) of Laboratory-CompactedSoils1This standard is issued under the fixed designation D 1883; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last

2、 revision. 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 Department of Defense.1NOTEEditorially corrected units in Section 6.2 in Ma

3、y 2009.1. Scope*1.1 This test method covers the determination of the CBR(California Bearing Ratio) of pavement subgrade, subbase, andbase course materials from laboratory compacted specimens.The test method is primarily intended for (but not limited to)evaluating the strength of materials having max

4、imum particlesizes less than34 in. (19 mm).1.2 When materials having maximum particle sizes 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. sieve while the total gravel(+No. 4 to

5、3 in.) fraction remains the same. While traditionallythis method of specimen preparation has been used to avoid theerror inherent in testing materials containing large particles inthe CBR test apparatus, the modified material may havesignificantly different strength properties than the originalmater

6、ial. However, a large experience base has developedusing this test method for materials for which the gradation hasbeen modified, and satisfactory design methods are in usebased on the results of tests using this procedure.1.3 Past practice has shown that CBR results for thosematerials having substa

7、ntial percentages of particles retainedon the No. 4 sieve are more variable than for finer materials.Consequently, more trials may be required for these materialsto establish a reliable CBR.1.4 This test method provides for the determination of theCBR of a material at optimum water content or a rang

8、e ofwater 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 D 698 or D 1557.1.5 The agency requesting the test shall specify the watercontent or range of water content and

9、the dry unit weight forwhich the CBR is desired.1.6 Unless specified otherwise by the requesting agency, 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 compactedmat

10、erials, see Test Method D 4429.1.8 The values stated in inch-pound units are to be regardedas the standard. The SI equivalents shown in parentheses maybe approximate.1.9 All observed and calculated values shall conform to theguidelines for significant digits and rounding established inPractice D 602

11、6.1.9.1 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

12、 forobtaining the data, special purpose studies, or any consider-ations for the users objectives, and it is common practice toincrease or reduce significant digits or reported data to becommensurate with these considerations. It is beyond the scopeof this standard to consider significant digits used

13、 in analyticalmethods for engineering design.1.10 This standard does not purport to address all of thesafety problems, 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 regul

14、atory limitations prior to use.1This test 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 Nov. 15, 2007. Published December 2007. Originallyapproved in 1961.

15、 Last previous edition approved in 2005 as D 1883 05.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.2. Referenced Documents2.1 ASTM Standards:2D 422 Test Method for P

16、article-Size Analysis of SoilsD 653 Terminology Relating to Soil, Rock, and ContainedFluidsD 698 Test Methods for Laboratory Compaction Character-istics of Soil Using Standard Effort (12 400 ft-lbf/ft3(600kN-m/m3)D 1557 Test Methods for Laboratory Compaction Charac-teristics of Soil Using Modified E

17、ffort (56,000 ft-lbf/ft3(2,700 kN-m/m3)D 2168 Test Methods for Calibration of LaboratoryMechanical-Rammer Soil CompactorsD 2216 Test Methods for Laboratory Determination of Wa-ter (Moisture) Content of Soil and Rock by MassD 2487 Practice for Classification of Soils for EngineeringPurposes (Unified

18、Soil Classification System)D 2488 Practice for Description and Identification of Soils(Visual-Manual Procedure)D 3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD 4318 Test Methods for Liquid Limit,

19、 Plastic Limit, andPlasticity Index of SoilsD 4429 Test Method for CBR (California Bearing Ratio) ofSoils in PlaceD 4753 Guide for Evaluating, Selecting, and SpecifyingBalances and Standard Masses for Use in Soil, Rock, andConstruction Materials TestingD 6026 Practice for Using Significant Digits in

20、 Geotechni-cal DataE11 Specification for Wire Cloth and Sieves for TestingPurposes3. Terminology3.1 Definitions: All definitions are in accordance with Ter-minology D 653.3.2 Definitions of Terms Specific to This Standard:3.2.1 water content of the compaction specimen, wiwatercontent in percent of m

21、aterial used to compact the 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 after soaking and penetration.3.2.3 water content after testing, wfwater content inpercent of material after soaking and final penetrat

22、ion; does notinclude material described in 3.2.2.3.2.4 dry density as compacted and before soaking, rdidrydensity 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 California Bearing Rati

23、o (CBR) test is a load testapplied to the surface and used in soil investigations as an aidto the 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 piston

24、 required to penetrate 0.1 in. (2.5 mm)and 0.2 in (5 mm) of the test soil to the unit load required topenetrate a standard material of well-graded crusted stone.4.2 This test method is used to determine the CBR of amaterial compacted in a specified mold. It is incumbent on therequesting agencies to

25、specify the scope of testing to satisfyagency protocol or specific design requirements. Possiblescope of testing includes:4.2.1 CBR penetration tests are performed on each point ofa compaction test performed in accordance with Method C ofD 698 or D 1557. The CBR mold with the spacer disk specifiedin

26、 this standard has the same internal dimensions as a 6-in.(150-mm) diameter compaction mold.4.2.2 Another alternative is for CBR test to be performed onmaterial compacted to a specific water content and density.Alternatively, a water content range may be stated for one ormore density values. This wi

27、ll 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 D 698 or D 1557 but varying the blows per layerto produce densities above an

28、d below the desired density.5. Significance and Use5.1 This test method is used to evaluate the potentialstrength of subgrade, subbase, and base course material,including recycled materials for use in road and airfieldpavements. The CBR value obtained in this test forms anintegral part of several fl

29、exible pavement 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

30、optimum water content ofa specified compaction effort. The dry unit weight specified isnormally the minimum percent compaction allowed by theusing agencys field compaction specification.5.3 For applications where the effect of compaction watercontent on CBR is unknown or where it is desired to accou

31、ntfor its effect, the CBR is determined for a range of watercontents, usually the range of water content permitted for fieldcompaction by using agencys field compaction specification.5.4 The criteria for test specimen preparation of self ce-menting (and other) materials which gain strength with time

32、must be based on a geotechnical engineering evaluation. Asdirected by the engineer, self-cementing materials shall beproperly cured until bearing ratios representing long termservice conditions can be measured.NOTE 1The agency performing this test can be evaluated in accor-dance with Practice D 3740

33、. Notwithstanding the statements on precisionand bias contained in this test method, the precision of this test method isdependent on the competence of the personnel performing it, and the2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at service

34、astm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.D18830712suitability of the equipment and facilities used. Agencies that meet thecriteria of Practice D 3740 are generally considered capable of competentand objective testi

35、ng. Users of this test method are cautioned thatcompliance with Practice D 3740 does not in itself ensure reliable testing.Reliable testing depends on many factors; Practice D 3740 provides ameans of evaluating some of those factors.6. Apparatus6.1 Loading MachineThe loading machine shall beequipped

36、 with a movable head or base that travels at a uniform(not pulsating) rate of 0.05 in. (1.27 mm)/min for use in forcingthe penetration piston into the specimen. The load rate of 0.05in. (1.27 mm)/min shall be maintained within 620% over therange of loads developed during penetration. The minimumcapa

37、city of the loading machine shall be based on the require-ments indicated in Table 1.6.1.1 The machine shall be equipped with a load-indicatingdevice matched to the anticipated maximum penetration load:10 lbf (44 N) or less for a 10-kip (44.5-kN) capacity; 5 lbf (22N) for 5-kip (22.3-kN) and 2 lbf (

38、8.9 N) for 2.5-kip (11.2-kN).6.1.2 Penetration measuring device (such as a mechanicaldial indicator or electronic displacement transducer) that can beread to the nearest 0.001 in. (0.025 mm) and associatedmounting hardware. A mounting assembly that connects thedeformation measuring device to the pen

39、etrating piston and theedge of the mold will give accurate penetration measurements.However, mounting the deformation holder assembly to astressed component of the load frame (such as tie rods) willintroduce inaccuracies of penetration measurements.6.2 MoldThe mold shall be a rigid metal cylinder wi

40、th aninside diameter of 6 6 0.026 in. (152.4 6 0.66 mm) and aheight of 7 6 0.018 in. (177.8 6 0.46 mm). It shall be providedwith a metal extension collar at least 2.0 in. (50.8 mm) inheight and a metal base plate having at least twenty eight116-in. (1.59-mm) diameter holes uniformly spaced over thep

41、late within the inside circumference of the mold. Whenassembled with spacer disc in place in the bottom of the mold,the mold shall have an internal volume (excluding extensioncollar) of 0.075 6 0.0009 ft3(2124 6 25 cm3). Fig. 1 shows asatisfactory mold design. A calibration procedure should beused t

42、o confirm the actual volume of the mold with the spacerdisk inserted. Suitable calibration procedures are contained inTest Methods D 698 and D 1557.6.3 Spacer DiskA circular metal spacer disc (see Fig. 1)having a minimum outside diameter of 51516 in. (150.8 mm)but no greater than will allow the spac

43、er disc to easily slip intothe mold. The spacer disc shall be 2.416 6 0.005 in. (61.37 60.127 mm) in height.6.4 RammerA rammer as specified in either Test MethodsD 698 or D 1557 except that if a mechanical rammer is used itmust be equipped with a circular foot, and when so equipped,must provide a me

44、ans for distributing the rammer blowsuniformly over the surface of the soil when compacting in a6-in. (152.4-mm) diameter mold. The mechanical rammer mustbe calibrated and adjusted in accordance with Test MethodsD 2168.6.5 Expansion-Measuring Apparatus An adjustable metalstem and perforated metal pl

45、ate, similar in configuration to thatshown in Fig. 1. The perforated plate shall be 578 to 51516 in.(149.23 to 150.81 mm) in diameter and have at least forty-two116-in. (1.59-mm) diameter holes uniformly spaced over theplate. A metal tripod to support the dial gauge for measuringthe amount of swell

46、during soaking is also required. Theexpansion measuring apparatus shall not weigh more than 2.8lbf (1.27 kg).6.6 WeightsOne or two annular metal weights having atotal mass of 4.54 6 0.02 kg and slotted metal weights eachhaving masses of 2.27 6 0.02 kg. The annular weight shall be578 to 51516 in. (14

47、9.23 to 150.81 mm) in diameter and shallhave a center hole of approximately 218 in. (53.98 mm).6.7 Penetration PistonA metal piston 1.954 6 0.005 in.(49.63 6 0.13 mm) in diameter and not less than 4 in. (101.6mm) long (see Fig. 1). If, from an operational standpoint, it isadvantageous to use a pisto

48、n of greater length, the longerpiston may be used.6.8 Swell Measurement DeviceGenerally mechanical dialindicators capable of reading to 0.001 in. (0.025 mm) with arange of 0.200-in. (5-mm) minimum.6.9 BalanceA class GP5 balance meeting the require-ments of Specifications D 4753 for a balance of 1-g

49、readability.6.10 Drying OvenThermostatically controlled, preferablyof a forced-draft type and capable of maintaining a uniformtemperature of 230 6 9F (110 6 5C) throughout the dryingchamber.6.11 Sieves3/4 in. (19 mm) and No. 4 (4.75 mm), con-forming to the requirements of Specification E11.6.12 Filter PaperFast filtering, high wet strength filterpaper, 15-cm diameter.6.13 StraightedgeA stiff metal straightedge of any conve-nient length but not less than 10 in. (254 mm). The total lengthof the straightedge shall be machined straight to a tolera