1、Designation: D 4429 04Standard 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 (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. Scope1.1 This test method covers the determination of the Cal
3、i-fornia Bearing Ratio (CBR) of soil tested in place by compar-ing the penetration load of the soil to that of a standardmaterial. This test method covers the evaluation of the relativequality of subgrade soils, but is applicable to subbase and somebase-course materials. This test method is designed
4、 to testin-situ materials and corresponds to Test Method D 1883.1.2 The values stated in inch-pound units are to be regardedas the standard.1.3 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 t
5、o 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 1556 Test Method for Density of Soil in Place by theSand-Cone MethodD 1883 Test Method for CBR (California Bearing Ratio) ofLabora
6、tory-Compacted SoilsD 2167 Test Method for Density of Soil in Place by theRubber-Balloon MethodD 2216 Method for Laboratory Determination of Water(Moisture) Content of Soil, Rock, and Soil-AggregateMixturesD 2937 Test Method for Density of Soil in Place by theDrive-Cylinder MethodD 3017 Test Method
7、for Water Content of Soil and Rock inPlace by Nuclear Methods (Shallow Depth)3. Significance and Use3.1 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 unsurfaced roads) for whi
8、ch 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 (per-centage of voids fille
9、d 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 last-named case, thewat
10、er 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.3.2 Any construction activities, such as grading or compact-ing, carried out subsequent
11、to the bearing ratio test willprobably invalidate the results of the test.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 direct application in testsection w
12、ork and in some expedient construction, military, or similaroperations. Also, as indicated in 3.1, field in-place tests can be used fordesign under conditions of nominal stability of water, density, and generalcharacteristics of the material tested. However, any significant treating,disturbing, hand
13、ling, compaction, or water change can affect the soilstrength and make the prior to test determination inapplicable, leading tothe need for retest and reanalysis.4. Apparatus4.1 Mechanical Screw JackA manually operated me-chanical screw jack equipped with a special swivel head forapplying the load t
14、o the penetration piston, and designed withthe following specifications:4.1.1 Minimum capacity of 5950 lb (2700 kg),4.1.2 Minimum lift of 2 in. (50 mm),4.1.3 Detachable handle, 6-in. (150-mm) radius,1This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct re
15、sponsibility of Subcommittee D18.08 on Special andConstruction Control Tests.Current edition approved Jan. 1, 2004. Published February 2004. Originallypublished as D 442984. Last previous edition D 442993.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer S
16、ervice at serviceastm.org. For Annual Book of ASTMStandardsvolume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.1.4 High-gear ratio, approximately 2.4 r
17、evolutions per0.04 in. (1 mm) of penetration,4.1.5 Medium-gear ratio, approximately 5 revolutions per0.04 in. (1 mm) of penetration, and4.1.6 Low-gear ratio, approximately 14 revolutions per 0.04in. (1 mm) of penetration.4.1.7 Other gear ratios may be used as desired if it is foundto be more conveni
18、ent to do so.4.1.8 Other mechanical jacks with 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.4.2 Proving RingsTwo calibrated proving rings havingthe following characteristics:4.2.1 Loading RangeOne proving load c
19、ell ring shallhave a loading range of approximately 0 to 1984 lbf (8.8 kN),and the other proving ring shall have a loading range ofapproximately 0 to 5070 lbf (22.6 kN).4.3 Penetration PistonThe penetration piston shall be 2 60.004 in. (50.8 6 0.1 mm) in diameter (nominal 3 in.2(2000mm2) and approxi
20、mately 4 in. (102 mm) in length.4.3.1 Piston Adapter and Pipe Extensions One pistonadapter and internally threaded pipe extensions with connec-tors.4.3.1.1 Pipe extensions shall be furnished in the followingquantities and lengths (or other combinations of lengthstotaling 8 ft (2.4 m):Number Required
21、 Approximate Length2 1.5 in. (38 mm)2 4 in. (102 mm)8 12 in. (305 mm)4.4 Dial GagesThere shall be two dial gages for measur-ing proving-ring deflections reading to 0.0001 in. (0.0025 mm)and having approximately 0.25-in. (6.4-mm) travel, and onedial gage for measuring penetration reading to 0.001 in.
22、 (0.025mm) and having approximately 1-in. (25-mm) travel, equippedwith an adjustable dial clamp extension.4.5 Support for Penetration DialOne support made of3-in. (76.2-mm) aluminum steel or wood channel approxi-mately 5 ft (1.5 m) long.4.6 Surcharge PlateA circular steel plate 10 6 0.02 in.(254 6 0
23、.5 mm) in diameter with 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).4.7 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
24、 8.5in. in diameter.4.8 Truck (Reaction)A truck (or piece of heavy equip-ment) 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 for forc
25、ing thepenetration 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
26、-ft (0.6-m)ground clearance is required to carry out the penetration test.4.9 JacksTwo truck-type jacks of 15-ton (14-Mg) capac-ity and having double-acting combination trip and automaticlowering.4.10 Miscellaneous ApparatusOther general apparatussuch as sample containers for water and density deter
27、mina-tions, spatula, straightedge, digging tools, etc.NOTE 2Fig. 1 shows a typical field setup for bearing ratio tests. Fig.2 shows the disassembled bearing ratio apparatus.5. Procedure5.1 Prepare the general surface area to be tested by remov-ing from the surface loose and dried material which is n
28、otrepresentative of the soil to be tested. Produce a test area whichFIG. 1 Setup for Field In-Place TestsD4429042is 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 sh
29、allbe 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.5.2 Locate the truck so that the center of the bearingattachment is directly over
30、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.5.
31、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 con
32、nectthe penetration piston. Clamp the jack in place. Check the levelmounted on the jack to be certain the assembly is vertical andadjust it if necessary.5.4 Place the “10-lb” (4.5-kg) surcharge plate beneath thepenetration piston so that when the piston is lowered it willpass through the center hole
33、.5.5 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.5.6 If nece
34、ssary 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.5.7 Add
35、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.NO
36、TE 3This 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).5.8 Attach the penetration dial clamp to the piston so thatthe dial rests upon the dial support.5.9 Set
37、 the dial gages to zero.5.10 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 rin
38、g at each 0.025-in. (0.64-mm)increment of penetration, to a final depth of 0.500 in. (12.70mm). In homogeneous soils, penetration depths greater than0.300 in. (7.62 mm) frequently may be omitted. Compute thestress for each increment of penetration in percent (see Section6 for calculations).5.11 At t
39、he 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 6 in.(100 to 150 mm) away from the point of penetration. Thedensity and water content shall be determined in accordancewith the ap
40、plicable test methods listed in Section 2.6. Calculation6.1 Stress Penetration CurveCalculate the penetrationstress for each penetration increment as applied force dividedby piston area. Plot the stress versus penetration curve for eachincrement of penetration, as shown in Fig. 3.FIG. 2 Apparatus fo
41、r Field In-Place TestsD44290436.1.1 In some instances the stress-penetration curve may beconcave upward initially because of surface irregularities orother causes, and in such cases the zero point shall be adjustedas shown in Fig. 3.6.2 CBRUsing corrected stress values taken from thestresspenetratio
42、n curve for 0.100 in. (2.54 mm) and 0.200-in.(5.08-mm) penetrations, calculate the bearing ratios for each bydividing the corrected stresses by the standard stresses of 1000psi (6.9 MPa) and 1500 psi (10.3 MPa) respectively, andmultiplying by 100. Also, calculate the bearing ratios for themaximum st
43、ress, if the penetration is less than 0.200 in.,interpolating the standard stress. The CBR reported for the soilmixture is normally the bearing ratio at 0.100-in. (2.54-mm)penetration. When the bearing ratio at 0.200-in. (5.08-mm)penetration (or at maximum penetration if less than 0.200 in.)is great
44、er, rerun the test. If the check test gives a similar result,the CBR is then taken as the bearing ratio determined at 0.200in. (5.08 mm) or at maximum penetration. No other bearingratios may be identified as CBR values.7. Report7.1 Report the following information on each test:7.1.1 Test location,7.
45、1.2 Material,7.1.3 Depth of test,7.1.4 Stress-penetration curve,7.1.5 Corrected bearing ratio at 0.1-in. (2.54-mm) penetra-tion,7.1.6 Corrected bearing ratio at 0.2-in. (5.08-mm) penetra-tion,7.1.7 Water content, and7.1.8 Density.8. Precision and Bias8.1 The precision and bias of this test method ha
46、s not beendetermined. Soils and flexible pavement components at thesame location may exhibit significantly different load deflec-tion relationships. No method presently exists to evaluate theprecision of a group of nonrepetitive plate load tests on soilsand flexible pavement components due to the va
47、riability ofthese materials. The subcommittee is seeking pertinent datafrom users of this test method which may be used to developmeaningful statements of precision and bias.9. Keywords9.1 bearing ratio; CBR; deflectionASTM International takes no position respecting the validity of any patent rights
48、 asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any ti
49、me by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This s
