1、Designation: D 1883 05Standard 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 (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope*1.1 This test method covers the determinatio
3、n 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 cohesive materials having maximumparticle sizes less than34 in. (19 mm).NOTE 1The
4、 agency performing this test can be evaluated in accor-dance with Practice D 3740.Not withstanding statements on precision and bias contained in thisStandard: The precision of this test method is dependent on the compe-tence of the personnel performing it and the suitability of the equipmentand faci
5、lities used. Agencies which meet the criteria of Practice D 3740are generally considered capable of competent and objective testing. Usersof this method are cautioned that compliance with Practice D 3740 doesnot in itself assure reliable testing. Reliable testing depends on manyfactors; Practice D 3
6、740 provides a means of evaluating some of thosefactors.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 grav
7、el( +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 havesignificantly different strength properties than the
8、 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 practice has shown that CBR results for thosematerials
9、 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 determination of theCBR of a material at optimum water con
10、tent 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 shall specify the watercontent or range of wate
11、r 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 topenetration.1.7 For the determination of CBR of fiel
12、d 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 This standard does not purport to address all of thesafety problems, if any, associated with its use. It is therespo
13、nsibility 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:2D 422 Test Method for Particle-Size Analysis of SoilsD 698 Test Method for Laboratory Compac
14、tion Character-istics of Soil Using Standard Effort (12,400 ft-lbf/ft3(600kN-m/m3)D 1557 Test Method for Laboratory Compaction Character-istics of Soil Using Modified Effort (56,000 ft-lbf/ft3(2,700 kN-m/m3)D 2168 Test Methods for Calibration of LaboratoryMechanical-Rammer Soil CompactorsD 2216 Test
15、 Method for Laboratory Determination of Water(Moisture) Content of Soil and Rock1This 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. 1, 2005. Publ
16、ished December 2005. Originallyapproved in 1961. Last previous edition approved in 1999 as D 1883 99.2For referenced ASTM standards, 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 D
17、ocument Summary page onthe ASTM website.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.D 2487 Classification of Soils for Engineering Purposes(Unified Soil Classifica
18、tion System)D 2488 Practice for Description and Identification of Soils(Visual-Manual Procedure)D 3740 Practice for Minimum Requirements of AgenciesEngaged in the Testing and/or Inspection of Soil and Rockas Used in Engineering Design and ConstructionD 4318 Test Method for Liquid Limit, Plastic Limi
19、t, andPlasticity Index of SoilsD 4429 Test Method for CBR (California Bearing Ratios)of Soils in Place3. Summary of Test Method3.1 For tests performed on materials compacted at one watercontent, three specimens are prepared. The specimens arecompacted using three different compactive efforts to obta
20、inunit weights both above and below the desired unit weight.After allowing specimens to take on water by soaking, or otherspecified treatment such as curing, each specimen is subjectedto penetration by a cylindrical rod. Results of stress (load)versus penetration depth are plotted to determine the C
21、BR foreach specimen. The CBR at the specified density is determinedfrom a graph of CBR versus dry unit weight.3.2 For tests in which the result is to be determined for awater content range, a series of specimens at each of threecompactive efforts are prepared over the range of watercontents requeste
22、d. The compactive efforts are chosen toproduce unit weights above and below the desired unit weight.After allowing the specimens to take on water by soaking, orother specified treatment such as curing, each specimen ispenetrated. Results are plotted to obtain the CBR for eachspecimen. A plot of CBR
23、versus unit weight for each watercontent is made to determine the minimum CBR for the rangeof water contents requested.4. Significance and Use4.1 This test method is used to evaluate the potentialstrength of subgrade, subbase, and base course material,including recycled materials for use in road and
24、 airfieldpavements. The CBR value obtained in this test forms anintegral part of several flexible pavement design methods.4.2 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 ofdi
25、ffering compaction water contents in the design procedure,the CBR may be determined at the optimum water content ofa specified compaction effort. The dry unit weight specified isnormally the minimum percent compaction allowed by theusing agencys field compaction specification.4.3 For applications wh
26、ere the effect of compaction watercontent on CBR is unknown or where it is desired to accountfor 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.4.4 The criteria for test
27、specimen preparation of self ce-menting (and other) materials which gain strength with timemust 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
28、.5. Apparatus5.1 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 machine shall beequipped with a load-indicating device that can be
29、read to 10lbf (44 N) or less. The minimum capacity of the loadingmachine shall be based on the requirements indicated in Table1.5.2 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 provi
30、dedwith 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 theplate within the inside circumference of the mold. Whenassembled with spacer disc in place in the bottom of the mold,the m
31、old shall have an internal volume (excluding extensioncollar) of 0.075 6 0.0009 ft (2124 6 25 cm). Fig. 1 shows asatisfactory 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
32、 Methods D 698 and D 1557.5.3 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 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.5.4 RammerA ra
33、mmer 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 means for distributing the rammer blowsuniformly over the surface of the soil when compacting in a6-in. (152.4-mm) diameter
34、mold. The mechanical rammer mustbe calibrated and adjusted in accordance with Test MethodsD 2168.5.5 Expansion-Measuring 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)
35、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 gage for measuring theamount of swell during soaking is also required.5.6 WeightsOne or two annular metal weights having atotal mass of 4.54 6 0.02 kg and slotte
36、d metal weights eachhaving masses of 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).TABLE 1 Minimum Load CapacityMaximum Measurable CBR Minimum Load Capacity(lbf) (kN)20 2500 11.250 5000 22
37、.350 10 000 44.5D18830525.7 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 piston of greater length, the longerpiston may be used.5.8 GagesTwo dial gag
38、es reading to 0.001 in. (0.025 mm)with a range of 0.200 minimum.5.9 Miscellaneous ApparatusOther general apparatussuch as a mixing bowl, straightedge, scales, soaking tank orpan, oven, fast filtering high wet strength filter paper, dishes,and 2-in.,34-in. and No. 4 sieves.6. Sample6.1 The specimen(s
39、) for compaction shall be prepared inaccordance with the procedures given in Test Methods D 698or D 1557 for compaction in a 6-in. (152.4-mm) mold exceptas follows:6.1.1 If all material passes a34-in. (19-mm) sieve, the entiregradation shall be used for preparing specimens for compactionwithout modi
40、fication. If material is retained on the34-in.(19-mm) sieve, the material retained on the34-in. (19-mm)sieve shall be removed and replaced by an equal amount ofmaterial passing the34-in. (19-mm) sieve and retained on theNo. 4 sieve obtained by separation from portions of the samplenot used for testi
41、ng.7. Test Specimens7.1 Bearing Ratio at Optimum Water Content OnlyUsingmaterial prepared as described in 6.1, conduct a controlcompaction test with a sufficient number of test specimens toestablish the optimum water content for the soil using thecompaction method specified, either Test Methods D 69
42、8 orD 1557. A previously performed compaction test on the samematerial may be substituted for the compaction test justdescribed, provided that if the sample contains material re-tained on the34-in. (19-mm) sieve, soil prepared as describedin 6.1 is used (Note 1).NOTE 2Maximum dry unit weight obtaine
43、d from a compaction testperformed in a 4-in. (101.6-mm) diameter mold may be slightly greaterthan the maximum dry unit weight obtained from compaction in the 6-in.(152.4-mm) compaction mold or CBR mold.7.1.1 For cases where the CBR is desired at 100 % maxi-mum dry unit weight and optimum water conte
44、nt, compact aspecimen using the specified compaction procedure, either TestMethods D 698 or D 1557, from soil prepared to within 60.5percentage point of optimum water content determined inaccordance with Test Method D 2216.NOTE 3Where the maximum dry unit weight was determined fromcompaction in the
45、4-in. (101.6-mm) mold, it may be necessary to compactspecimens as described in 7.1.2, using 75 blows per layer or some othervalue sufficient to produce a specimen having a density equal to or greaterthan that required.7.1.2 Where the CBR is desired at optimum water contentand some percentage of maxi
46、mum dry unit weight, compactthree specimens from soil prepared to within 60.5 percentagepoint of optimum water content and using the specifiedcompaction but using a different number of blows per layer forTABLE 2 Metric EquivalentsInch-PoundUnits, in.MetricEquivalent,mmInch-PoundUnits, in.MetricEquiv
47、alent,mmInch-PoundUnits, in.MetricEquivalent,mm0.003 0.0761932 15.08 312 88.900.005 0.12758 15.88 334 95.250.135 3.4334 19.10 414 108.00.201 5.111516 23.81 412 114.30.4375 11.11 1 25.40 434 120.70.4378 11.12 118 28.58 578 149.20.510 12.95 114 31.8 51516 150.80.633 16.08 138 34.9 6 152.01.370 34.60 1
48、12 38.10 6732 158.01.375 34.93 134 44.5 612 165.11.954 49.63 11316 46.04 7 177.82.416 61.37 11516 49.21 712 190.1116 1.59 2 50.80 838 212.7732 5.56 218 53.98 812 215.914 6.35 215 55.9 938 238.138 9.53 214 57.2 1414 362.0716 11.11 212 63.50 18 457.21532 11.91 234 69.85 3214 719.212 12.70 23132 75.41
49、3658 930.31732 13.49 3 76.20 39 990.6Inch-PoundUnits, lbMetricEquivalent, kgInch-PoundUnits, psiMetricEquivalent, MPa0.04 0.02 200 1.40.05 0.02 400 2.80.12 0.05 600 4.10.59 0.27 800 5.50.71 0.32 1000 6.90.75 0.34 1200 8.33.20 1.45 1400 9.75.0010.002.274.54D1883053each specimen. The number of blows per layer shall be variedas necessary to prepare specimens having unit weights aboveand below the desired value. Typically, if the CBR for soil at95 % of maximum dry unit weight is desired, specimenscompacted using 5
