1、Designation: D 5874 02 (Reapproved 2007)Standard Test Method forDetermination of the Impact Value (IV) of a Soil1This standard is issued under the fixed designation D 5874; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year o
2、f last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the determination of the ImpactValue (IV) of a soil either in the field or a test mold.1.2
3、 The standard test method, using a 4.5 kg (10 lbm)hammer, is suitable for, but not limited to, evaluating thestrength of an unsaturated compacted fill, in particular pave-ment materials, soils, and soil-aggregates having maximumparticle sizes less than 37.5 mm (1.5 in.).1.3 By using a lighter 0.5 kg
4、 (1.1 lbm) hammer, this testmethod is applicable for evaluating lower strength soils such asfine grained cohesionless, highly organic, saturated, or highlyplastic soils having a maximum particle size less than 9.5 mm(0.375 in.).1.4 By performing laboratory test correlations for a particu-lar soil us
5、ing the 4.5 kg (10 lbm) hammer, IV may be correlatedwith an unsoaked California Bearing Ratio (CBR) or may beused to infer percentage compaction.1.5 The values stated SI are to be regarded as the standard.The values stated in parentheses are given for information only.1.6 All observed and calculated
6、 values shall conform to theguidelines for significant digits and rounding established inPractice D 6026. The method used to specify how data arecollected, calculated, or recorded in this standard is not directlyrelated to the accuracy to which the data can be applied indesign or other uses or both.
7、 How one applies the resultsobtained using this standard is beyond its scope.1.7 This standard may involve hazardous materials, opera-tions, and equipment. This standard does not purport toaddress all of the safety concerns, if any, associated with itsuse. It is the responsibility of the user of thi
8、s standard toestablish appropriate safety and health practices and deter-mine the applicability of regulatory limitations prior to use.NOTE 1The equipment and procedures contained in this test methodare similar to those developed by B. Clegg in the 1970s at the Universityof Western Australia, Nedlan
9、ds, Australia. Impact Value is also commonlyknown as Clegg Impact Value (CIV).2. Referenced Documents2.1 ASTM Standards:2D 653 Terminology Relating to Soil, Rock, and ContainedFluidsD 698 Test Methods for Laboratory Compaction Character-istics of Soil Using Standard Effort (12,400 ft-lbf/ft3(600kN-m
10、/m3)D 1556 Test Method for Density and Unit Weight of Soil inPlace by the Sand-Cone MethodD 1557 Test Methods for Laboratory Compaction Charac-teristics of Soil Using Modified Effort (56,000 ft-lbf/ft3(2,700 kN-m/m3)D 1883 Test Method for CBR (California Bearing Ratio) ofLaboratory-Compacted SoilsD
11、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 2922 Test Methods for Density of Soil and Soil-Aggregate in Place by Nuclear Methods (Shallow Depth)D 2937
12、Test Method for Density of Soil in Place by theDrive-Cylinder MethodD 3740 Practice for Minimum Requirements for AgenciesEngaged in the Testing and/or Inspection of Soil and Rockas Used in Engineering Design and ConstructionD 4643 Test Method for Determination of Water (Moisture)Content of Soil by t
13、he Microwave Oven MethodD 4959 Test Method for Determination of Water (Moisture)Content of Soil By Direct HeatingD 6026 Practice for Using Significant Digits in Geotechni-cal Data3. Terminology3.1 DefinitionsExcept as listed below, all definitions arein accordance with Terminology D 653.3.1.1 impact
14、 value (IV), nthe value expressed in units oftens of gravities (g) derived from the peak decelaration of a 4.51This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.08 on Special andConstruction Control Tests.Current edit
15、ion approved May 1, 2007. Published July 2007. Originally approvedin 1995. Last previous edition approved in 2002 as D 587402.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information,
16、 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 International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.kg (10 lbm) instrumented compaction hammer 50 mm (1.97
17、in.) in diameter free falling 450 mm (18 in.).3.1.2 light impact value (IV/L), nthe IV derived fromusing a 0.5 kg (1.1 lbm) mass hammer 50 mm (1.97 in.) indiameter free falling 300 mm (12 in.).3.1.3 impact soil tester, ntesting apparatus used to obtainan IV of a soil.3.1.4 target iv, nthe desired st
18、rength, in terms of IV, to beachieved in the field for a particular material and constructionprocess. This may also be referred to as target strength.4. Summary of Test Method4.1 The test apparatus is placed on the material to be testedeither in a mold or on naturally occurring or compacted soil int
19、he field. The hammer is raised to a set height and allowed tofree fall. The instrumentation of the test apparatus displays avalue in tens of gravities (g) of the peak deceleration of thehammers impact as recorded by an accelerometer fitted to thetop of the hammer body. A total of four blows of the h
20、ammerare applied on the same spot to determine the IV for each testperformed.4.2 A light hammer of 0.5 kg (1.1 lbm) may be used forsofter conditions or fragile materials instead of the 4.5 kg (10lbm) standard hammer to determine the IV. When used theresulting value is termed the Light Impact Value (
21、IV/L).5. Significance and Use5.1 Impact Value, as determined using the standard 4.5 kg(10 lbm) hammer, has direct application to design and con-struction of pavements and a general application to earthworkscompaction control and evaluation of strength characteristicsof a wide range of materials, suc
22、h as soils, soil aggregates,stabilized soil and recreational turf. Impact Value is one of theproperties used to evaluate the strength of a layer of soil up toabout 150 mm (6 in.) in thickness and by inference to indicatethe compaction condition of this layer. Impact Value reflectsand responds to cha
23、nges in physical characteristics that influ-ence strength. It is a dynamic force penetration property andmay be used to set a strength parameter.5.2 This test method provides immediate results in terms ofIV and may be used for the process control of pavement orearthfill activities where the avoidanc
24、e of delays is importantand where there is a need to determine variability whenstatistically based quality assurance procedures are being used.5.3 This test method does not provide results directly as apercentage of compaction but rather as a strength index valuefrom which compaction may be inferred
25、 for the particularmoisture conditions. From observations, strength either re-mains constant along the dry side of the compaction curve orelse reaches a peak and declines rapidly with increase in watercontent slightly dry of optimum water content. This is gener-ally between 95 and 98 % maximum dry d
26、ensity (see Fig. 1 andFig. 2).Afield target strength in terms of IV may be designatedfrom laboratory testing or field trials for a desired density andwater content. If testing is performed after compaction whenconditions are such that the water content has changed from thecritical value, determinati
27、on of the actual water content bylaboratory testing enables the field density to be inferred fromregression equations using IV, density and water content.NOTE 2Impact Value may be used as a means to improve thecompaction process by giving instant feedback on roller efficiency,uniformity, confirming
28、the achievement of the target strength, and byinference the achieved density. When inferring density from IV, however,it should be considered as only indicative of density. Where strictacceptance on a density ratio basis is required, test methods that measuredensity directly shall be used.5.4 This t
29、est method may be used to monitor strengthchanges during a compaction process or over time due toseasonal, environmental or traffic changes.NOTE 3For in-place soil strength evaluation where there may be a dryand hard surface layer (crust), testing both the crust and the underlyinglayer may be requir
30、ed.5.5 The standard instrument is based on a 4.54 kg (10 lbm)compaction hammer using a 457.2 mm (18 in.) drop height.The hammer has been equipped with an accelerometer andinstrumented using a peak hold electronic circuit to read thepeak deceleration on impact. The circuitry is filtered electroni-cal
31、ly to remove unwanted frequencies and the peak decelera-tion is displayed in units of ten gravities (g) with the outputbelow units of ten gravities truncated.5.6 The peak deceleration on which IV is derived representsthe area under the deceleration versus time curve which formost soils may be assume
32、d as half a sinusoid. Applying doubleintegration provides first the time velocity relationship andsecond, the time penetration relationship. As force is alsodirectly related to deceleration, the IV therefore, representsFIG. 1 Illustration of Target IV for Material With No Peak but DropD 5874 02 (200
33、7)2both stress and penetration and may be taken as a directmeasurement of stiffness or strength (see Fig. 3).5.7 Impact Value may be correlated with an unsoaked CBR.5.8 Impact Value may be expressed as a hammer modulus,analogous with elastic modulus or deformation modulus.5.9 The light hammer uses t
34、he same accelerometer andinstrumentation as the standard hammer. The smaller mass of0.5 kg (1.1 lbm) results in more sensitivity for lower strengthmaterials compared to the standard mass; that is, the zero to100 IV scale is expanded with this lighter hammer mass andprovides more definition on softer
35、 materials. To avoid confu-sion, the IV of the light hammer is notated as IV/L.5.10 Light Impact Value has applications for recreation turfhardness evaluation, where the condition of the surface affectsball bounce characteristics, the performance or injury potentialto participants, and where more se
36、nsitivity compared to thestandard hammer is required or an imprint left by the 4.5 kg (10lbm) hammer or other test methods is undesirable, such as ona golf putting green.NOTE 4The agency performing this test method can be evaluated inaccordance with Practice D 3740. Not withstanding oil precision an
37、d biascontained 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 generally considered capable of competentand objective te
38、sting. Users of this test method are cautioned thatcompliance with Practice D 3740 does not assure reliable testing. Reliabletesting depends on many factors, and Practice D 3740 provides a means ofevaluating some of those factors.6. Apparatus6.1 Impact Soil TesterA test apparatus consisting of ahamm
39、er, guide tube, and electronic instrumentation. Detailedinformation on the apparatus is contained in Annex A1.Atypical configuration is shown in Fig. 4.6.2 MoldA 152.4 mm (6 in.) diameter mold conformingto the requirements of Test Methods D 698 Procedure C,D 1557 Procedure C, or D 1883 with a spacer
40、 disc.6.2.1 Molds of other, typically larger, dimensions may beused but must be reported accordingly in the report.NOTE 5For a particular material, the smaller 101.6 mm (4 in.) moldmay be used if it has been proven by a laboratory test comparison with the152.4 mm (6 in.) mold that there is no signif
41、icant difference in the IVresults.7. Procedure7.1 Operational Verification Checks Perform operationalverification checks at the commencement of any testing pro-gram, after repair, or when the instrument is suspect using theoperational check ring as follows.FIG. 2 Illustration of Target IV for Materi
42、al With Pronounced PeakFIG. 3 Development of Force-Penetration from DecelerationVersus TimeD 5874 02 (2007)37.1.1 Place the ring on a dry, grease free smooth hardsurface of a solid massive object, such as a concrete floor overground. Place the guide tube centrally over the ring and dropthe hammer fi
43、ve times from the set height mark as described inA2.1.3 for the standard 4.5 kg hammer or A2.1.4 for the light0.5 kg hammer. Operate the instrumentation so as to obtain fiveseparate readings. If this operational check procedure givessignificantly different values than shown on the ring, examinethe d
44、ryness, cleanliness, smoothness and firmness of thesupport for the ring and the ring itself and review theoperational check procedure and rerun the check at the same oranother location. If the ring value is not satisfactorily achiev-able, an electronic check may be carried out according to themanufa
45、cturers calibration instruction for the accelerometer.NOTE 6To avoid the possibility of damage to the electronics or thehammer, the impact soil tester should not be used directly on hard surfacessuch as concrete or otherwise in such a way on materials that it would giveresults of more than 100 IV (1
46、000 g).NOTE 7The impact energy provided by the 4.5 kg hammer can causeundesired damage to surfaces and materials such as brick or concretepaving slabs or smoothly prepared turf surfaces.7.2 Determine an IV as follows.7.2.1 The peak deceleration that is the highest of the foursuccessive blows is take
47、n as the IV. The maximum of the firstfour blows has been found through experiment and practice tobe the simplest means by which to obtain consistent results.Analysis of the blow count has shown that the first blow or twomay be considered as seating procedure as they create acompacted wedge or hemisp
48、here of soil that is subsequentlyforced into the body of the soil causing an increase indeceleration, that is, an increase in IV, as successive blows areapplied. In general, deceleration remains practically unchangedafter the third or fourth blow with additional blows continuingto produce a constant
49、 amount of penetration. If lower valuesoccur with subsequent blows, this is due apparently to thehammer striking the sides of the indentation or by loosematerial falling onto the strike surface causing a bias in thisdirection.7.2.2 Impact Values obtained from other blow counts, or anaverage thereof, shall be reported accordingly in the report.7.3 Field Procedure AIf necessary, prepare the surface ofthe compacted or natural soil to be tested by lightly scuffingwith the foot to remove loose surface material. Before begin-ning a test, ensure that the hammer strike f
