1、Designation: D5873 14Standard 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). This test method appliesonly to hammers with an impact energy not to exceed 0.735Nm. Hammers with energies above 0.735 Nm tend to breakthe rock and are n
7、ot recommended.1.5 Rocks exhibiting vesicular texture may be beyond thescope of this test. Care should be taken when testing such rocksand conglomerates as the rebound values will vary betweentesting a large piece of aggregate versus softer matrix of theconglomerate.1.6 All observed and calculated v
8、alues shall conform to theguidelines for significant digits and rounding established inPractice D6026.1.6.1 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 digi
9、ts that generally should be retained. The proce-dures used do not consider material variation, purpose forobtaining the data, special purpose studies, or any consider-ations for the users objectives; and it is common practice toincrease or reduce significant digits of reported data to becommensurate
10、 with these considerations. It is beyond the scopeof this standard to consider significant digits used in analyticalmethods for engineering design.1.7 For determining the rebound number of concrete, seeTest Method C805/C805M.1.8 UnitsThe values stated in SI units are to be regardedas standard. No ot
11、her units of measurement are included in thisstandard.1.9 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 health practices and determine the applica-bility
12、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 Determination of Water(Moisture) Content of Soil and Rock by
13、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 to Dimensionaland Shape Tolerances1This test metho
14、d 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 Feb. 1, 2014. Published February 2014. Originallyapproved in 1995. Last previous edition approved in 2013 as D5873 13. DOI:10.1520/D5873
15、-14.2Brown, 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 Customer Service at serviceastm.org. For Annual B
16、ook 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 19428-2959. United States1D4879 Guide for
17、Geotechnical Mapping of Large Under-ground Openings in RockD6026 Practice for Using Significant Digits in GeotechnicalDataD7012 Test Methods for Compressive Strength and ElasticModuli of Intact Rock Core Specimens under VaryingStates of Stress and Temperatures3. Terminology3.1 DefinitionsFor definit
18、ions of common technical termsin this standard, refer to 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.3.2.2 rebound hardness number, HRa dimensionless num
19、-ber representing empirically determined, relative hardness ofrock material or other hard substance by use of a reboundhammer.3.2.3 rebound numbera dimensionless reading or valuebased on the absorption of part of the stored elastic energy ofthe spring through plastic deformation of the rock surface
20、andmechanical waves propagating through the stone while theremaining elastic energy causes the actual rebound of thehammer.3.2.3.1 DiscussionThe rebound distance traveled by thespring loaded steel mass, expressed as a percentage of theinitial extension of the spring, is called the rebound number.Kol
21、aiti and Papadopoulos (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 Guide D
22、4879, 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 tunnel bo
23、ring 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 approxima
24、tely 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, rebound
25、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 generally
26、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. Inte
27、rferences5.1 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 Differen
28、t 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 to de
29、termine 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 produce a
30、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 with the
31、rock 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. The hammermust travel with a fixed and reproducible speed. The reboun
32、ddistance of the hammer from the top of the steel plunger ismeasured through the use of a mechanical slider or electronicdisplay and is taken as an empirical measure of rock hardness.6.2 Core HolderA steel V-block or steel cradle with asemi-circular machined slot with a minimum mass of 20 kg towhich
33、 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 cradle shall be the same radius as the coreto be tested.Aguide may be attached to the core holder to
34、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 a computer for analysis.NOTE 4An evaluation is made of three different holders for hammertests o
35、n rock core in the laboratory, including steel angle, V-block, andsemi-circular groove holders. The differences are small, but it is shown4Kolaiti E., and Papadopoulos Z., Evaluation of Schmidt Rebound HammerTesting: A Critical Approach, Bulletin of the International Association of Engineer-ing Geol
36、ogy, 1993.D5873 142that the V-block holder gives consistently higher rebound hardness 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 fo
37、rconventional use.6.3 Verification AnvilA verification block or cylinder, asshown in Fig. 3, is used to determine the current value of therebound hammer against the value supplied by the manufac-turer. The size of the verification anvil should match the sizeneeded for the type of rebound hammer bein
38、g used and madeof tool steel with an impact area hardened as hard as theplunger tip, which 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-grai
39、ned texture silicon car-bide or equivalent material to grind smooth the surface stone ofthe test area if it is heavily textured. A hand operated abrasivestone, as seen in Fig. 4, may be used to achieve the desiredsmoothness. In addition, an abrasive stone attached to a powertool may also be used.7.
40、Sampling7.1 Samples can be drill core, NX or larger, rock blocks, orin situ rock surfaces, 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.T
41、est in situ rock surfaces or obtain samples by direct samplingof rock that correlate with 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, excav
42、a-tion damage, or is otherwise not representative of the rockmaterial of interest. If relevant 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 suitabi
43、lity for use of the rebound hammerFor example, a very soft rock will scratch with a fingernail 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. 1 Typical Rebound H
44、ammer with Correction Graph for Non-Vertical Use and Rebound Scale on the Side of the Body forManual ReadingsFIG. 2 Example of a Rebound Hammer Against a Rock CoreSpecimen in the Core Holder (the Clamp for Holding the Speci-men is Not Shown)FIG. 3 Verification Anvil with Instrument GuideD5873 1438.
45、Specimen Preparation8.1 Drill core specimens shall be NX or larger core and atleast 15 cm in length. Block specimens shall have edge 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 ar
46、eas at least 15 cm indiameter.8.2 For a block or core specimen, determine its length bytaking the average of four lengths measured 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 diam
47、eters measured at right angles toeach other approximately midway along the length of thespecimen and record to the nearest 5 mm.8.4 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,
48、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 specimens, 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
49、 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 heavily 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 calibrated once every 12months and whenever there is reason to question their properoperation.NOTE 5Different manufacturers recommend checki
