1、Designation: D 1883 072Standard 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 2009.2NOTEEditorially corrected units in Section 10.3 in July 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
4、not limited to)evaluating the strength of materials having maximum 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 test
5、s all passes the34-in. sieve while the total gravel(+No. 4 to 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 havesign
6、ificantly different strength properties than the originalmaterial. 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 practi
7、ce has shown that CBR results for thosematerials having substantial 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 determinat
8、ion of theCBR of a material at optimum water content or a range 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
9、 shall specify the watercontent or range of water content and 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 topene
10、tration.1.7 For the determination of CBR of field compactedmaterials, 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 fo
11、r significant digits and rounding established inPractice D 6026.1.9.1 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. Th
12、e 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 toincrease or reduce significant digits or reported data to becommensurate with these considerations. It is beyond
13、 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 problems, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety
14、and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 422 Test Method for Particle-Size Analysis of SoilsD 653 Terminology Relating to Soil, Rock, and ContainedFluids1This test method is under the jurisdiction ofASTM
15、 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. Last previous edition approved in 2005 as D 1883 05.2For referenced ASTM standar
16、ds, 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.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM Interna
17、tional, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.D 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
18、Effort (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
19、 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
20、, 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 i
21、n Geotechni-cal DataE11 Specification for Woven Wire Test Sieve Cloth andTest Sieves3. 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
22、 material 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 penetr
23、ation; 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 Ra
24、tio (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 pist
25、on 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 t
26、o 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 specified
27、in 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
28、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 D 698 or D 1557 but varying the blows per layerto produce densities above
29、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 material,including recycled materials for use in road and airfieldpavements. The CBR value obtained in this test forms anintegral part of several
30、flexible 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 th
31、e 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 acc
32、ountfor 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 ti
33、memust 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 37
34、40. 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 thesuitability of the equipment and facilities used. Agencies that meet thecriteria of Practice D 3740 are genera
35、lly considered capable of competentand objective testing. 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
36、.1 Loading MachineThe loading machine shall beequipped 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
37、of loads developed during penetration. The minimumD18830722capacity 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
38、(44.5-kN) capacity; 5 lbf (22N) for 5-kip (22.3-kN) and 2 lbf (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 as
39、sembly that connects thedeformation measuring device to the penetrating 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 m
40、easurements.6.2 MoldThe mold shall be a rigid metal cylinder with 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 e
41、ight116-in. (1.59-mm) diameter holes uniformly spaced over theplate 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 asa
42、tisfactory mold design. A calibration procedure should beused to 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
43、 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 60.127 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 equipp
44、ed 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-in. (152.4-mm) diameter mold. The mechanical rammer mustbe calibrated and adjusted in accordance with Test MethodsD 2168.6.5 Expansion-Meas
45、uring Apparatus An adjustable metalstem and perforated metal plate, 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 tri
46、pod to support the dial gauge for measuringthe amount of swell 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
47、2.27 6 0.02 kg. The annular weight shall be578 to 51516 in. (149.23 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, f
48、rom an operational standpoint, it isadvantageous to use a piston 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 t
49、he require-ments of Specifications D 4753 for a balance of 1-g 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
