1、Designation: D 4429 09Standard Test Method forCBR (California Bearing Ratio) of Soils in Place1This standard is issued under the fixed designation D 4429; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A
2、 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.1. Scope*1.1 This test method covers the determination of the Cal
3、i-fornia Bearing Ratio (CBR) of soil tested in place by thepenetration load of the soil. This test method covers theevaluation of the relative quality of subgrade soils, but isapplicable to subbase and some base-course materials. This testmethod is designed to test in-situ materials and corresponds
4、toTest Method D 1883.1.2 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in
5、 non-conformancewith the standard.1.2.1 In the engineering profession it is customary to useunits representing both mass and force interchangeably, unlessdynamic calculations are involved. This implicitly combinestwo separate systems of units, that is, the absolute system andthe gravitational system
6、. It is scientifically undesirable tocombine the use of two separate sets of inch-pound units withina single standard. This test method has been written using thegravitational system of units when dealing with the inch-poundsystem. In this system, the pound (lbf) represents a unit of force(weight).
7、However, conversions are given in the SI System.The use of balances or scales recording pounds of mass (lbm),or the recording of density in lbm/ft3 should not be regarded asnonconformance with this test method.1.3 All observed and calculated values shall conform to theguidelines for significant digi
8、ts and rounding established inPractice D 6026, unless superseded by this standard.1.3.1 The procedures used to specify how data are collected/recorded or calculated in this standard are regarded as theindustry standard.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 shou
9、ld be retained. The proce-dures used do not consider material variation, purpose forobtaining the data, special purpose studies, or any consider-ation for the users objectives; and it is common practice toincrease or reduce significant digit of reported data to becommensurate with these consideratio
10、ns. It is beyond the scopeof this standard to consider significant digits used in analysismethods or engineering design.1.4 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-pr
11、iate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 653 Terminology Relating to Soil, Rock, and ContainedFluidsD 1556 Test Method for Density and Unit Weight of Soil inPlace by Sand-Cone MethodD 1883 Te
12、st Method for CBR (California Bearing Ratio) ofLaboratory-Compacted SoilsD 2167 Test Method for Density and Unit Weight of Soil inPlace by the Rubber Balloon MethodD 2216 Test Methods for Laboratory Determination of Wa-ter (Moisture) Content of Soil and Rock by MassD 2937 Test Method for Density of
13、Soil in Place by theDrive-Cylinder MethodD 3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD 6026 Practice for Using Significant Digits in Geotechni-cal DataD 6780 Test Method for Water Content and
14、Density of Soilin Place by Time Domain Reflectometry (TDR)D 6938 Test Method for In-Place Density and Water Con-tent of Soil and Soil-Aggregate by Nuclear Methods(Shallow Depth)3. Terminology3.1 Definitions: All definitions are in accordance with Ter-minology D 653.1This test method is under the jur
15、isdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.08 on Special andConstruction Control Tests.Current edition approved May 15, 2009. Published May 2009. Originallyapproved in 1984. Last previous edition approved in 2004 as D 4429 04.2For referenced A
16、STM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandardsvolume 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 AS
17、TM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4. Significance and Use4.1 Field in-place CBR tests are used for evaluation anddesign of flexible pavement components such as base andsubbase course and subgrades and for other applications (suchas
18、unsurfaced roads) for which CBR is the desired strengthparameter. If the field CBR is to be used directly for evaluationor design without consideration for variation due to change inwater content, the test should be conducted under one of thefollowing conditions: (a) when the degree of saturation (p
19、er-centage of voids filled with water) is 80 % or greater, (b) whenthe material is coarse grained and cohesionless so that it is notsignificantly affected by changes in water content, or ( c) whenthe soil has not been modified by construction activities duringthe two years preceding the test. In the
20、 last-named case, thewater content does not actually become constant, but generallyfluctuates within a rather narrow range. Therefore, the fieldin-place test data may be used to satisfactorily indicate theaverage load-carrying capacity.4.2 Any construction activities, such as grading or compact-ing,
21、 carried out subsequent to the bearing ratio test willprobably invalidate the results of the test.4.3 Soils and flexible pavement components at the samelocation may exhibit significantly different load deflectionrelationships. No method presently exists to evaluate theprecision of a group of non-rep
22、etitive plate load tests on soilsand flexible pavement components due to the variability ofthese materials.NOTE 1Field in-place tests are used to determine the relative strengthof soils, subbase, and some base materials in the condition at which theyexist at the time of testing. Such results have di
23、rect application in testsection work and in some expedient construction, military, or similaroperations. Also, as indicated in 4.1, field in-place tests can be used fordesign under conditions of nominal stability of water, density, and generalcharacteristics of the material tested. However, any sign
24、ificant treating,disturbing, handling, compaction, or water change can affect the soilstrength and make the prior to test determination inapplicable, leading tothe need for retest and reanalysis.NOTE 2Notwithstanding the statements on precision and bias con-tained in this standard: The precision of
25、this test method is dependent onthe competence of the personnel performing it and the suitability of theequipment and facilities used.Agencies which meet the criteria of PracticeD 3740 are generally considered capable of competent and objectivetesting. Users of this method are cautioned that complia
26、nce with PracticeD 3740 does not in itself assure reliable testing. Reliable testing dependson many factors; Practice D 3740 provides a means of evaluating some ofthose factors.5. Apparatus5.1 Mechanical Screw JackA manually operated me-chanical screw jack equipped with a special swivel head forappl
27、ying the load to the penetration piston, and designed withthe following specifications:5.1.1 Minimum capacity of 5950 lb (2700 kg),5.1.2 Minimum lift of 2 in. (50 mm),5.1.3 Detachable handle, 6-in. (150-mm) radius,5.1.4 High-gear ratio, approximately 2.4 revolutions per0.04 in. (1 mm) of penetration
28、,5.1.5 Medium-gear ratio, approximately 5 revolutions per0.04 in. (1 mm) of penetration, and5.1.6 Low-gear ratio, approximately 14 revolutions per 0.04in. (1 mm) of penetration.5.1.7 Other gear ratios may be used as desired if it is foundto be more convenient to do so.5.1.8 Other mechanical jacks wi
29、th the same maximum loadand lift may be utilized, provided that a uniform load-penetration rate of 0.05 in. (1.3 mm)/min can be achieved.5.2 Load MeasurementTwo calibrated proving rings or aload cell having the following characteristics:5.2.1 Proving RingsOne proving ring shall have a loadingrange o
30、f approximately 0 to 1984 lbf (8.8 kN), and the otherproving ring shall have a loading range of approximately 0 to5070 lbf (22.6 kN).5.3 Penetration PistonThe penetration piston shall be 2 60.004 in. (50.8 6 0.1 mm) in diameter (nominal 3 in.2(2000mm2) and approximately 4 in. (102 mm) in length.5.3.
31、1 Piston Adapter and Pipe Extensions One pistonadapter and internally threaded pipe extensions with connec-tors.5.3.1.1 Pipe extensions shall be furnished in the followingquantities and lengths (or other combinations of lengthstotaling 8 ft (2.4 m):Number Required Approximate Length2 1.5 in. (38 mm)
32、2 4 in. (102 mm)8 12 in. (305 mm)5.4 Dial GaugesTwo dial gauges (if proving rings areused) for measuring proving-ring deflections reading to 0.0001in. (0.0025 mm) and having approximately 0.25-in. (6.4-mm)travel. One dial gauge for measuring the penetration reading to0.001 in. (0.025 mm) and having
33、approximately 1-in. (25-mm)travel, equipped with an adjustable dial clamp extension.5.5 Support for Penetration DialOne support made of3-in. (76.2-mm) aluminum steel or wood channel approxi-mately 5 ft (1.5 m) long.5.6 Surcharge PlateA circular steel plate 10 6 0.02 in.(254 6 0.5 mm) in diameter wit
34、h a 2 6 0.02-in. (50.8 60.5-mm) diameter hole in the center. The plate shall weigh 106 0.02 lb (4.54 6 0.01 kg).5.7 Surcharge WeightsTwo “10-lb” (4.54 6 0.01-kg)slotted surcharge weights 8.5 in. (216 6 1 mm) in diameter,and two “20-lb” (9.08 6 0.01-kg) slotted surcharge weights 8.5in. in diameter.5.
35、8 Truck (Reaction load)A truck (or piece of heavyequipment) loaded sufficiently to provide a reaction of approxi-mately 6970 lbf (31 kN). The truck shall be equipped with asuitable metal beam and an attachment, or attachments, at therear end in order to provide a reaction load for forcing thepenetra
36、tion piston into the soil. Suitable attachments or otherprovision shall be provided so that the truck may be jackedsufficiently to take the load off of the rear springs in order topermit the penetration test to be carried out without upwardmovement of the truck chassis. Approximately 2-ft (0.6-m)gro
37、und clearance is required to carry out the penetration test.5.9 JacksTwo truck-type jacks of 15-ton (14-Mg) capac-ity and having double-acting combination trip and automaticlowering. Alternatively, hydraulic leveling jacks can be used.D44290925.10 Miscellaneous ApparatusOther general apparatussuch a
38、s sample containers for water and density determina-tions, spatula, straightedge, digging tools, etc.NOTE 3Fig. 1 shows a typical field setup for bearing ratio tests. Fig.2 shows the disassembled bearing ratio apparatus.6. Procedure6.1 Prepare the general surface area to be tested by remov-ing from
39、the surface loose and dried material which is notrepresentative of the soil to be tested. Produce a test area whichis as smooth and horizontal as practicable. Where nonplasticbase materials are encountered, extreme care shall be taken notto disturb the test surface. Spacing of the penetration tests
40、shallbe such that operations at one point will not disturb the soil atthe next point to be penetrated. This spacing may range from aminimum of 7.0 in. (175 mm) in plastic soils to 15 in. (380mm) in coarse granular soils.6.2 Locate the truck so that the center of the bearingattachment is directly ove
41、r the surface to be tested. Install themechanical screw test jack with the swivel to the underside ofthe reaction attachment. Place the truck jacks under each sideof the truck and lift the truck so that little or no weight rests onthe rear springs, making sure that the truck is level across theback.
42、6.3 Position the mechanical screw jack to the correct posi-tion for the test, and connect the proving ring to the end of jack.Then, attach the piston adapter to the bottom of the provingring, connect the necessary number of extensions to comewithin 4.9 in. (125 mm) of the surface to be tested, and c
43、onnectthe penetration piston. Clamp the jack in place. Check the levelmounted on the jack to be certain the assembly is vertical andadjust it if necessary.6.4 Place the “10-lb” (4.5-kg) surcharge plate beneath thepenetration piston so that when the piston is lowered it willpass through the center ho
44、le.6.5 Seat the penetration piston under a load of approxi-mately 3 psi (21 kPa). For rapid setting, use the high-gear ratioof the jack. For base materials with an irregular surface, set thepiston on the thinnest practical layer of fine limestone screen-ings (2040 mesh) or plaster of paris.6.6 If ne
45、cessary in order to achieve a smooth surface, raisethe surcharge plate while the seating load is on the piston andevenly spread clean fine sand to a depth of 0.12 to 0.24 in. (3to 6 mm) over the surface to be covered by the plate. Thisserves to distribute the weight of the surcharge uniformly.6.7 Ad
46、d surcharge weights to the surcharge plate so that theunit load is equivalent to the load intensity of the material orpavement which will overlie the subgrade or base, or both,except that the minimum weight applied shall be the “10-lb”(4.5-kg) surcharge plate plus one “20-lb” (9-kg) surchargeweight.
47、NOTE 4This minimum weight creates an intensity of loading equal tothat created by the “10-lb” surcharge weight used in the 6-in. (150-mm)diameter mold in the laboratory CBR test (Test Method D 1883).6.8 Attach the penetration dial clamp to the piston so thatthe dial rests upon the dial support.6.9 S
48、et the dial gauges to zero.6.10 Apply the load to the penetration piston so that the rateof penetration is approximately 0.05 in. (1.3 mm)/min. Byusing the low-gear ratio of the jack during the test, a uniformrate of penetration can be maintained by the operator. Recordthe deflection of the proving
49、ring or load cell reading at each0.025-in. (0.64-mm) increment of penetration to the nearest 25lbf (111 kN), to a final depth of 0.500 in. (12.70 mm). Inhomogeneous soils, penetration depths greater than 0.300 in.(7.62 mm) frequently may be omitted. Compute the stress foreach increment of penetration in percent (see Section 7 forcalculations).FIG. 1 Setup for Field In-Place TestsD44290936.11 At the completion of the test obtain a sample at thepoint of penetration and determine its water content. A densitydetermination should also be made at a location about 4 to
