ASTM D1883-2016 Standard Test Method for California Bearing Ratio (CBR) of Laboratory-Compacted Soils《实验室压实土壤的加州承载比 (CBR) 的标准试验方法》.pdf

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1、Designation: D1883 14D1883 16Standard 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

2、 last 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 U.S. Department of Defense.1. Scope*1.1 This test method covers the de

3、termination of the California Bearing Ratio (CBR) of pavement subgrade, subbase, and basecourse materials from laboratory compacted specimens. The test method is primarily intended for, but not limited to, evaluatingthe strength of materials having maximum particle size less than 34 in. (19 mm).1.2

4、When materials having a maximum particle size greater than 34 in. (19 mm) are to be tested, this test method provides formodifying the gradation of the material so that the material used for teststesting all passes the 34-in. (19-mm) sieve while the totalgravel (3 in. (75 mm) to plus No. 4 (4.75 mm)

5、 fraction fraction (material passing the 3-in. (75-mm) sieve and retained on the No.4 (4.75-mm) sieve) remains the same. While traditionally this method of specimen preparation has been used to avoid the errorinherent in testing materials containing large particles in the CBR test apparatus, the mod

6、ified material may have significantlydifferent strength properties than the original material. However, a large experience database has been developed using this testmethod for materials for which the gradation has been modified, and satisfactory design methods are in use based on the resultsof test

7、s using this procedure.1.3 Past practice has shown that CBR results for those materials having substantial percentages of particles retained on the No.4 (4.75 mm) sieve are more variable than for finer materials. Consequently, more trials may be required for these materials toestablish a reliable CB

8、R.1.4 This test method provides for the determination of the CBR of a material at optimum water content or a range of watercontent from a specified compaction test and a specified dry unit weight. The dry unit weight is usually given as a percentage ofmaximum dry unit weight determined by Test Metho

9、ds D698 or D1557.1.5 The client requesting the test may specify the water content or range of water contents and the dry unit weight for whichthe CBR is desired.1.6 Unless specified otherwise by the requesting client, or unless it has been shown to have no effect on test results for thematerial bein

10、g tested, all specimens shall be soaked prior to penetration.1.7 For the determination of CBR of field in-place materials, see Test Method D4429.1.8 UnitsThe values stated in inch-pound units are to be regarded as standard. The SI units given in parentheses aremathematical conversions, which are pro

11、vided for information purposes only and are not considered standard. Reporting of testresults in units other than inch-pound units shall not be regarded as nonconformance with this test method.1.8.1 The gravitational system of inch-pound units is used when dealing with inch-pound units. In this syst

12、em, the pound (lbf)represents a unit of force (weight), while the unit for mass is slugs. The slug unit is not given, unless dynamic (F = ma) calculationsare involved.1.8.2 The slug unit of mass is almost never used in commercial practice; that is, density, balances, etc. Therefore, the standardunit

13、 for mass in this standard is either kilogram (kg) or gram (g), or both. Also, the equivalent inch-pound unit (slug) is notgiven/presented in parentheses.1.8.3 It is common practice in the engineering/construction profession, in the United States, to concurrently use pounds torepresent both a unit o

14、f mass (lbm) and of force (lbf). This implicitly combines two separate systems of units; that is, the absolutesystem and the gravitational system. It is scientifically undesirable to combine the use of two separate sets of inchpound units1 This test method is under the jurisdiction of ASTM Committee

15、 D18 on Soil and Rock and is the direct responsibility of Subcommittee D18.05 on Strength andCompressibility of Soils.Current edition approved Dec. 1, 2014March 1, 2016. Published January 2015March 2016. Originally approved in 1961. Last previous edition approved in 20072014 asD1883 07D1883 14.2. DO

16、I: 10.1520/D1883-14.10.1520/D1883-16.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM re

17、commends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box

18、C700, West Conshohocken, PA 19428-2959. United States1within a single standard. As stated, this standard includes the gravitational system of inch-pound units and does not use/presentthe slug unit for mass. However, the use of balances or scales recording pounds of mass (lbm) or recording density in

19、 lbm/ft3 shallnot be regarded as nonconformance with this standard.1.8.4 The terms density and unit weight are often used interchangeably. Density is mass per unit volume whereas unit weightis force per unit volume. In this standard, density is given only in SI units. After the density has been dete

20、rmined, the unit weightis calculated in SI or inch-pound units, or both.1.9 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in PracticeD6026.1.9.1 The procedures used to specify how data are collected/recorded or calculated in this s

21、tandard are regarded as the industrystandard. In addition they are representative of the significant digits that generally should be retained. The procedures used do notconsider material variation, purpose for obtaining the data, special purpose studies, or any considerations for the users objective

22、s,and it is common practice to increase or reduce significant digits orof reported data to be commensurate with these considerations.It is beyond the scope of this standard to consider significant digits used in analytical methods for engineering design.1.10 This standard does not purport to address

23、 all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C670 Practice for P

24、reparing Precision and Bias Statements for Test Methods for Construction MaterialsD422 Test Method for Particle-Size Analysis of Soils (Withdrawn 2016)3D653 Terminology Relating to Soil, Rock, and Contained FluidsD698 Test Methods for Laboratory Compaction Characteristics of Soil Using Standard Effo

25、rt (12,400 ft-lbf/ft3 (600 kN-m/m3)D1557 Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort (56,000 ft-lbf/ft3 (2,700kN-m/m3)D2168 Practices for Calibration of Laboratory Mechanical-Rammer Soil CompactorsD2216 Test Methods for Laboratory Determination of Water (Mois

26、ture) Content of Soil and Rock by MassD2487 Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System)D2488 Practice for Description and Identification of Soils (Visual-Manual Procedure)D3740 Practice for Minimum Requirements for Agencies Engaged in Testing an

27、d/or Inspection of Soil and Rock as Used inEngineering Design and ConstructionD4318 Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of SoilsD4429 Test Method for CBR (California Bearing Ratio) of Soils in PlaceD4753 Guide for Evaluating, Selecting, and Specifying Balances and Stan

28、dard Masses for Use in Soil, Rock, and ConstructionMaterials TestingD6026 Practice for Using Significant Digits in Geotechnical DataE11 Specification for Woven Wire Test Sieve Cloth and Test Sieves3. Terminology3.1 Definitions:3.1.1 For common definitions of terms in this standard, refer to Terminol

29、ogy D653.3.2 Definitions of Terms Specific to This Standard:3.2.1 water content of the compaction specimen, wiwater content in percent of material used to compact the test specimen.3.2.2 water content top 1 in. (25.4-mm) after soaking wswater content in percent of upper 1 in. (25.4 mm) of material r

30、emovedfrom the compacted specimen after soaking and penetration.3.2.3 water content after testing, wfwater content in percent of the compacted specimen after soaking and final penetration;does not include material described in 3.2.2.3.2.4 dry density as compacted and before soaking, didry density of

31、 the as compacted test specimen using the measured wetmass and calculating the dry mass using the water content defined in 3.2.1.4. Summary of Test Method4.1 The California Bearing Ratio (CBR) test is used in evaluating subgrade, subbase and base materials as an aid to the designof pavements. The la

32、boratory test uses a circular piston to penetrate material compacted in a mold at a constant rate of penetration.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the

33、standards Document Summary page on the ASTM website.3 The last approved version of this historical standard is referenced on www.astm.org.D1883 162The CBR is expressed as the ratio of the unit load on the piston required to penetrate 0.1 in. (2.5 mm) and 0.2 in (5.1 mm) of thetest material to the un

34、it load required to penetrate a standard material of well-graded crushed stone.4.2 This test method is used to determine the CBR of a material compacted in a specified mold. It is incumbent on the requestingclient to specify the scope of testing to satisfy the clients protocol or specific design req

35、uirements. Possible scope of testingincludes:4.2.1 CBR penetration tests can be performed on each point of a compaction test performed in accordance with Method C ofD698 or D1557. The CBR mold with the spacer disk specified in this standard has the same internal dimensions as a 6.000-in.(152.4-mm) d

36、iameter compaction mold.4.2.2 Another alternative is for the CBR test to be performed on material compacted to a specific water content and density.Alternatively, a water content range may be stated for one or more density values and will often require a series of specimensprepared using two or thre

37、e compactive efforts for the specified water contentcontents or over the range of water contentsrequested. The compactive efforts are achieved by following procedures of D698 or D1557 but varying the blows per layer toproduce densities above and below the desired density.5. Significance and Use5.1 T

38、his test method is used to evaluate the potential strength of subgrade, subbase, and base course materials, includingrecycled materials for use in the design of road and airfield pavements. The CBR value obtained in this test forms an integral partof several flexible pavement design methods.5.2 For

39、applications where the effect of compaction water content on CBR is small, such as cohesionless, coarse-grainedmaterials, or where an allowance is made for the effect of differing compaction water contents in the design procedure, the CBRmay be determined at the optimum water content of a specified

40、compaction effort. The specified dry unit weight is normally theminimum percent compaction allowed by the using clients field compaction specification.5.3 For applications where the effect of compaction water content on CBR is unknown or where it is desired to account for itseffect, the CBR is deter

41、mined for a range of water contents, usually the range of water content permitted for field compaction byusing the clients protocol or specification for field compaction.5.4 The criteria for test specimen preparation of self-cementing (and other) materials which gain strength with time must bebased

42、on a geotechnical engineering evaluation. As directed by the client, self-cementing materials shall be properly cured untilbearing ratios representing long term service conditions can be measured.NOTE 1The quality of the results produced by this standard is dependent on the competence of the personn

43、el performing it, and the suitability of theequipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objectivetesting/sampling/inspection/etc. Users of this standard are cautioned that compliance with Practice D3740 does not i

44、n itself ensure reliable results.Reliable results depend on many factors; Practice D3740 provides a means of evaluating some of those factors.6. Apparatus6.1 Loading MachineThe loading machine shall be equipped with a movable head or base that travels at a uniform (notpulsating) rate of 0.05 in. (1.

45、3 mm)/min for use in pushing the penetration piston into the specimen. The load rate of 0.05 in. (1.3mm)/min shall be maintained within 620% over the range of loads developed during penetration. The minimum capacity of theloading machine shall be based on the requirements indicated in Table 1.6.1.1

46、The machine shall be equipped with a load-indicating device matched to the anticipated maximum penetration load. Theload-indicating device shall have a minimum accuracy of: 10 lbf (44 N) or less for a 10,000 lbf (44 kN) capacity; 5 lbf (20(22 N)or less for 5,000 lbf (22 kN) and 2 lbf (9 N) or less f

47、or 2,500 lbf (11 kN).6.2 Penetration Measuring DeviceThe penetration measuring device (such as a mechanical dial indicator or electronicdisplacement transducer) shall be capable of reading to the nearest 0.001 in. (0.025 mm) and provided with appropriate mountinghardware. The mounting assembly of th

48、e deformation measuring device shall be connected to the penetrating piston and the edgeof the mold providing accurate penetration measurements. Mounting the deformation holder assembly to a stressed component ofthe load frame (such as tie rods) will introduce inaccuracies of penetration measurement

49、s.TABLE 1 Minimum Load CapacityMaximum Measurable CBR Minimum Load Capacity(lbf) (kN)20 2500 11.250 5000 22.350 5,000 22.350 10 000 44.550 10,000 44.5D1883 1636.3 MoldThe mold shall be a rigid metal cylinder with an inside diameter of 6.000 6 0.026 in. (152.4 6 0.66 mm) and aheight of 7.000 6 0.018 in. (177.8 6 0.46 mm). It shall be provided with a metal extension collar at least 2.0 in. (50.8 mm) inheight and a metal base plate having at least twenty eight 116-in. (1.59-mm) diameter holes uniformly spaced over the plate withinthe inside circumference of