1、Designation: D5873 13Standard Test Method forDetermination of Rock Hardness by Rebound HammerMethod1This standard is issued under the fixed designation D5873; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisio
2、n. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the testing apparatus, sampling,test specimen preparation, and testing procedures for determin-ing the re
3、bound hardness number of rock material using aspring-driven steel hammer, referred to variously as a reboundhammer, impact test hammer, or concrete test hammer.1.2 This test method is best suited for rock material withuniaxial compressive strengths ranging between approximately1 and 100 MPa. Test Me
4、thod D7012 provides more informa-tion on compressive strength of rock.1.3 The portable testing apparatus may be used in thelaboratory or field to provide a means of rapid assessment ofrock hardness or to serve as an indicator of rock hardness.1.4 Rebound hammers are available from their originalmanu
5、facturers in several different energy ranges. For a givenplunger tip diameter and radius of curvature, the impact energyof the rebound hammer determines its range of applicability.Accordingly, this limitation should be kept in mind whenselecting a hammer type. Earlier recommendations for rockmechani
6、cs applications were only for hammers with an impactenergy of 0.735 Nm, especially on smaller core samples andweaker rocks (see also Brown 19812). Any rebound hammermay be used, however, this test method applies only tohammers with an impact energy not to exceed 0.735 Nm.Hammers with energies above
7、0.735 Nm tend to break the rockand are not recommended.1.5 All observed and calculated values shall conform to theguidelines for significant digits and rounding established inPractice D6026.1.6 This test method is used to test rock. For concretetesting, see Test Method C805/C805M.1.7 The values stat
8、ed in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.8 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and
9、 health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:3C805/C805M Test Method for Rebound Number of Hard-ened ConcreteD653 Terminology Relating to Soil, Rock, and ContainedFluidsD2216 Test Methods for Laboratory Determinat
10、ion of Water(Moisture) Content of Soil and Rock by MassD3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD4543 Practices for Preparing Rock Core as Cylindrical TestSpecimens and Verifying Conformance
11、 to Dimensionaland Shape TolerancesD4879 Guide for Geotechnical Mapping of Large Under-ground Openings in RockD6026 Practice for Using Significant Digits in GeotechnicalDataD7012 Test Method for Compressive Strength and ElasticModuli of Intact Rock Core Specimens under VaryingStates of Stress and Te
12、mperatures3. Terminology3.1 For common definitions of terms in this standard, referto Terminology D653.3.2 Definitions of Terms Specific to This Standard:3.2.1 rebound hammera portable, spring loaded, steelhammer used to classify the hardness of rock in the field orlaboratory. Fig. 1 is an example o
13、f a typically rebound hammer.1This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.12 on Rock Mechanics.Current edition approved July 1, 2013. Published July 2013. Originally approvedin 1995. Last previous edition approv
14、ed in 2005 as D5873 05. DOI: 10.1520/D5873-13.2Brown, E. T., ed., Suggested Methods: Rock Characterization, Testing, andMonitoring, International Society of Rock Mechanics (ISRM): Pergamon Press,London, 1981.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Custome
15、r Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA
16、19428-2959. United States13.2.2 rebound hardness number, HRa dimensionless num-ber representing empirically determined, relative hardness ofrock material or other hard substance by use of a reboundhammer. The number is based on the absorption of part of thestored elastic energy of the spring through
17、 plastic deformationof the rock surface and mechanical waves propagating throughthe stone while the remaining elastic energy causes the actualrebound of the hammer. The rebound distance traveled by themass, expressed as a percentage of the initial extension of thespring, is called the Rebound number
18、. Kolaiti and Papado-poulos (1993)44. Significance and Use4.1 The rebound hardness method provides a means forrapid classification of the hardness of rock during site charac-terization for engineering, design, and construction purposes,geotechnical mapping of large underground openings in rock,see G
19、uide D4879, or reporting the physical description of rockcore, see Practice D4543.4.2 The rebound hardness number, HR, can serve in avariety of engineering applications that require characterizationof rock material. These applications include, for examples, theprediction of penetration rates for tun
20、nel boring machines,determination of rock quality for construction purposes, group-ing of test specimens, and prediction of hydraulic erodibility ofrock.4.3 This test method is of limited use on very soft rock orvery hard rock, which is defined as having uniaxial compres-sive strengths less than app
21、roximately 1 MPa or greater than100 MPa.4.4 The results of this test method are not intended forconversion to strength data suitable for design.NOTE 1Several types of rebound hammers are commercially availableto accommodate testing of various sizes and types of rock. For the samerock or material, re
22、bound numbers obtained from different hammers arenot comparable.NOTE 2The quality of the result produced by 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 D3740 are gene
23、rally considered capable of competentand objective testing and sampling. Users of this test method are cautionedthat compliance with Practice D3740 does not in itself assure reliableresults. Reliable results depend on many factors; Practice D3740 providesa means of evaluating some of those factors.5
24、. Interferences5.1 Rock at 0 C or less may exhibit very high reboundvalues.5.2 Temperature of the rebound hammer itself may affectthe rebound number. The hammer and materials to be testedshould be at the same temperature.5.3 For readings to be compared, the direction of impactmust be the same.5.4 Di
25、fferent instruments of the same nominal design maygive rebound numbers differing from one to three units andtherefore, tests should be made with the same instrument inorder to compare results. If more than one instrument is to beused, a sufficient number of tests must be made on typical rocksurfaces
26、 to determine the magnitude of the differences to beexpected in the readings of different instruments.5.5 Rocks exhibiting vesicular texture may be beyond thescope of this test. The open texture may continue throughoutthe entire specimen and no practical amount of abrasive stoneapplication will prod
27、uce a consistent test surface. The honey-combed nature of the material may readily fail giving a falselylow hardness value.6. Apparatus6.1 Rebound HammerA device consisting of a spring-loaded steel hammer with a predetermined amount of energythat, when released, strikes a metal plunger in contact wi
28、th therock core or natural surface. Fig. 1 is an example of a typicalrebound hammer. Fig. 2 is an example of the rebound hammeragainst a rock core specimen that is held in a metal anvil incontact with, and supported by, a solid surface. Fig. 3 is anexample of the use of a hammer perpendicular to the
29、 testsurface. The hammer must travel with a fixed and reproducible4Kolaiti E., and Papadopoulos Z., Evaluation of Schmidt Rebound HammerTesting: A Critical Approach, Bulletin of the International Association of Engineer-ing Geology, 1993.FIG. 1 Typical Rebound Hammer with Correction Graph for Non-Ve
30、rtical Use and Rebound Scale on the Side of the Body forManual ReadingsD5873 132speed. The rebound distance of the hammer from the top of thesteel plunger is measured through the use of a mechanicalslider or electronic display and is taken as an empiricalmeasure of rock hardness.6.2 Core HolderA ste
31、el V-block or steel cradle with asemi-circular machined slot with a minimum mass of 20 kg towhich specimens are securely held with some type of clampingdevice. See Note 4 for more information on test holders. Rockcore specimens must be firmly seated in the base for the test.The slot in the test crad
32、le shall be the same radius as the coreto be tested.Aguide may be attached to the core holder to keepthe rebound hammer perpendicular to the surface of the testspecimen. Fig. 2 shows this positioning.NOTE 3Instruments are available that will store the rebound numbers,which can then be transferred to
33、 a computer for analysis.NOTE 4An evaluation is made of three different holders for hammertests on rock core in the laboratory, including steel angle, V-block, andsemi-circular groove holders. The differences are small, but it is shownthat the V-block holder gives consistently higher rebound hardnes
34、s values.It is also easier and more economical to build since you do not need adifferent size semi-circular grooved holder for each core size. Thesequalities indicate the V-block holder would be a better selection forconventional use.6.3 Calibration AnvilA calibration block or cylinder, asshown in F
35、ig. 4, is used to determine the current value of therebound hammer against the value supplied by the manufac-turer. The size of the calibration anvil should match the sizeneeded for the type of rebound hammer being used and madeof tool steel with an impact area hardened as hard as theplunger tip, wh
36、ich is typically Brinell 500 or Rockwell HRC52. An instrument guide is provided to center the reboundhammer over the impact area to keep the instrument perpen-dicular to the surface.6.4 Abrasive StoneA medium-grained texture silicon car-bide or equivalent material to grind smooth the surface stone o
37、fthe test area if it is heavily textured. A hand operated abrasivestone, as seen in Fig. 5, may be used to achieve the desiredsmoothness. In addition, an abrasive stone attached to a powertool may also be used.7. Sampling7.1 Samples can be drill core, NX or larger, rock blocks, orin situ rock surfac
38、es, such as tunnel walls.7.2 Samples shall be of sufficient size and quantity toproduce the required specimens and cover the rock material ofinterest.7.3 Samples shall be representative of the rock to be studied.Test in situ rock surfaces or obtain samples by direct samplingof rock that correlate wi
39、th the subsurface rock units of interest.Test specimens may be drill core or blocks of rock materialfrom outcrops. Avoid sampling and testing rock materialweakened by weathering, discontinuities, alteration, excava-tion damage, or is otherwise not representative of the rockmaterial of interest. If r
40、elevant to the test program, record theorientation of block samples.7.4 The rebound hammer is generally unsuitable for verysoft or very hard rock; therefore, conduct simple field tests toquickly assess the suitability for use of the rebound hammerFor example, a very soft rock will scratch with a fin
41、gernail andpeel with a pocketknife and an intact specimen of very hardrock breaks only by repeated, heavy blows with a geologicalhammer and cannot be scratched with a common 20d steel nail.FIG. 2 Example of a Rebound Hammer Against a Rock CoreSpecimen in the Core Holder (the Clamp for Holding the Sp
42、eci-men is Not Shown)FIG. 3 Example of a Hand-Held Rebound Hammer Perpendicularto the Test Surface in the FieldFIG. 4 Calibration Anvil with Instrument GuideD5873 1338. Specimen Preparation8.1 Drill core specimens shall be NX or larger core and atleast 15 cm in length. Block specimens shall have edg
43、e lengthsof at least 15 cm. Rock surfaces tested in place, includingnatural outcrops or prepared surfaces, such as tunnel walls orfloors, shall have smooth, flat test areas at least 15 cm indiameter.8.2 For a block or core specimen, determine its length bytaking the average of four lengths measured
44、at four equallyspaced points on the circumference and record to the nearest 5mm.8.3 For a block or core specimen, determine its diameter bytaking the average of two diameters measured at right angles toeach other approximately midway along the length of thespecimen and record to the nearest 5 mm.8.4
45、 Record or document the moisture condition of the blockor core specimen(s). Depending on the requirements of the testprogram, the qualitative condition can be reported, such asair-dried or in situ moisture, or a more exact method can beused such as Test Method D2216.8.5 The test surface of all speci
46、mens, either in the laboratoryor in the field, shall be smooth to the touch or free of joints,fractures, or other obvious localized discontinuities to a depthof at least 6 cm. In situ rock shall be flat and free of surface gritover the area covered by the plunger. If the surface of the testarea is h
47、eavily textured, grind it smooth with the abrasive stonedescribed in 6.4.9. Calibration9.1 Calibration of the hammer is essential to maintain itsstandard rebound values before and after field investigationsand to make sure accurate test results are obtained. Reboundhammers shall be serviced and cali
48、brated once every 12months and whenever there is reason to question their properoperation.NOTE 5Different manufacturers recommend checking the calibrationvalues after either 1000 to 2000 rebound tests.9.2 Prior to each testing sequence, check the calibration ofthe hammer using a calibration test anv
49、il supplied by themanufacturer for that purpose.9.2.1 In instances where the core holder is used for tests,place the calibration anvil in the core holder and obtain tenrebound hammer readings on the anvil.9.2.2 Operation of the rebound hammer is satisfactory if thecalibration readings fall within the range provided by themanufacturer. If the calibrations readings fall outside thisrange, the instrument must be cleaned, adjusted, or returned tothe manufacturer for correction.9.2.3 In correlation studies, two consistent readings withinthe predetermined range of rebound va
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