1、Designation: D 5873 05Standard Test Method forDetermination of Rock Hardness by Rebound HammerMethod1This standard is issued under the fixed designation D 5873; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revis
2、ion. 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 testing apparatus, sampling,test specimen preparation, and testing procedures for determin-ing the
3、 rebound 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 (see Test Method D 7012)ranging between approxim
4、ately 1 and 100 MPa.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 The values stated in SI units are to be regarded as thestandard.1.5 This standard does not purport to a
5、ddress 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 of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C 805 Test
6、Method for Rebound Number of HardenedConcreteD 420 Guide to Site Characterization for Engineering, De-sign, and Construction PurposesD 653 Terminology Relating to Rock, Soil, and ContainedFluidsD 3740 Practice for Minimum Requirements for AgenciesEngaged in the Testing and/or Inspection of Soil and
7、Rockas Used in Engineering Design and ConstructionD 4543 Practice for Preparing Rock Core Specimens andDetermining Dimensional and Shape TolerancesD 4879 Guide for Geotechnical Mapping of Large Under-ground Openings in RockD 7012 Test Test Method for Compressive Strength andElastic Moduli of Intact
8、Rock Core Specimens underVarying States of Stress and Temperatures2.2 ISRM Standards:Suggested Method for Determination of Schmidt ReboundHardness3Suggested Method for Quantitative Description of Discon-tinuities in Rock Masses33. Terminology3.1 For common definitions of terms in this standard, refe
9、rto Terminology D 653.3.2 Definitions of Terms Specific to This Standard:3.2.1 rebound hammera portable, spring loaded, piston-type, steel hammer used to classify the hardness of rock in thefield or laboratory.3.2.2 rebound hardness numberHR, a dimensionless num-ber representing empirically determin
10、ed, relative hardness ofrock material or other hard substance by use of a reboundhammer.4. 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(see Guide D
11、 420), geotechnical mapping of large undergroundopenings in rock (see Guide D 4879), or reporting the physicaldescription of rock core (see Practice D 4543). The reboundhardness number, Hr, can serve in a variety of engineeringapplications that require characterization of rock material.These applica
12、tions include, for examples, the prediction ofpenetration rates for tunnel boring machines, determination ofrock quality for construction purposes, and prediction ofhydraulic erodibility of rock.4.2 This test method is of limited use on very soft rock orvery hard rock (unconfined compressive strengt
13、hs less thanapproximately 1 MPa or greater than 100 MPa).4.3 The results of this test method are not intended forconversion to strength data suitable for design.1This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.12 on
14、 Rock Mechanics.Current edition approved Nov. 1, 2005. Published November 2005. Originallyapproved in 1995. Last previous edition approved in 2005 as D 5873 00(2005)e1.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual
15、 Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Brown, E. T., ed., Suggested Methods: Rock Characterization, Testing, andMonitoring, International Society of Rock Mechanics: Pergamon Press, London,1981.1*A Summary of Changes section appears
16、 at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.NOTE 1Several types of rebound hammers are commercially avail-able to accommodate testing of various sizes and types of concreteconstruction (See Test Method
17、 C 805) and rock material.NOTE 2The quality of the result produced by this standard 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 competentan
18、d objective testing and sampling. Users of this standard are cautionedthat compliance with Practice D 3740 does not in itself assure reliableresults. Reliable results depend on many factors; Practice D 3740 providesa means of evaluating some of those factors.5. Apparatus5.1 Rebound Hammer, consistin
19、g of a spring-loaded piston,or hammer, which is projected against a metal anvil in contactwith the rock surface. The hammer must travel with a fixed andreproducible velocity. The rebound distance of the piston fromthe steel plunger is measured in a linear scale attached to theframe of the instrument
20、 and is taken as an empirical measure ofrock hardness.5.2 Steel BaseA steel base of minimum mass of 20 kg towhich specimens are securely fastened. Rock core specimensmay be tested in a steel cradle with a semicylindrical machinedslot of the same radius as the core, or firmly seated in a steelV-block
21、, see Suggested Method for Determination of SchmidtRebound Hardness.5.3 Calibration AnvilThe standard calibration block usedto calibrate the rebound hammer.5.4 Abrasive StoneA medium-grained texture silicon car-bide or equivalent material.6. Sampling6.1 Drill core specimens shall be NX or larger cor
22、e of 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 a smooth, flat test area at least 15 cm indiameter.6.2 Samples shall be representative of th
23、e rock to be studied.Obtain samples by direct sampling of subsurface rock unitswith core borings or by sampling blocks of rock material fromoutcrops that correlate with the subsurface rock unit of interest.At surface outcrops, avoid sampling and testing rock materialweakened by weathering or alterat
24、ion or is otherwise unrepre-sentative of the rock material of interest, see Suggested Methodfor Quantitative Description of Discontinuities in RockMasses.6.3 The rebound hammer is generally unsuitable for verysoft or very hard rock. Conduct simple field tests to quicklyassess a rock materials suitab
25、ility for the rebound hammer testmethod. Scratch very soft rock with a fingernail and peel witha pocket knife. An intact specimen of very hard rock breaksonly by repeated, heavy blows with a geological hammer andcannot be scratched with a common 20d steel nail.7. Specimen Preparation7.1 For a block
26、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.7.2 For a block or core specimen, determine its diameter bytaking the average of two diameters measured at right angles toeach other ap
27、proximately midway along the length of thespecimen and record to the nearest 5 mm.7.3 Report the moisture condition of the block or specimen.7.4 The test surface of all specimens, either in the laboratoryor in the field, shall be smooth to the touch and free of joints,fractures, or other obvious loc
28、alized 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 heavily textured, grind it smooth with the abrasive stonedescribed in 5.4.8. Calibration8.1 Prior to each testing sequence, ca
29、librate the hammerusing a calibration test anvil supplied by the manufacturer forthat purpose.8.1.1 Place the calibration anvil in the core holder andconduct ten readings on the anvil.8.1.2 Calculate the correction factor by dividing the manu-facturers standard hardness value for the anvil by the av
30、erageof the ten readings taken on the anvil.NOTE 3If the instrument reads lower than the manufacturers stan-dard hardness value, the correction factor will be greater than unity. If thereadings are higher, the correction factor will be less than unity.NOTE 4Operation of the rebound hammer is satisfa
31、ctory if thecalibration readings fall within the range provided by the manufacturer. Ifthe calibration readings fall outside this range, the instrument must becleaned, adjusted, or returned to the manufacturer for correction.NOTE 5Rebound hammers require periodic servicing and verificationto provide
32、 reliable results.9. Procedure9.1 Place the steel base on a flat, level surface that providesfirm, rigid support, such as a concrete floor.9.2 Securely clamp rock core specimens in a steel cradlewith a semicylindrical machined slot of the same radius as thecore, or firmly seat into a steel V-shaped
33、block. Securely clampblock specimens to the rigid steel base in such a manner as toprevent vibration and movement of the specimen during thetest.9.3 For tests conducted on specimens in the laboratory,orient the instrument within 5 of vertical with the bottom ofthe piston at right angles to and in fi
34、rm contact with the surfaceof the test specimen. A guide may be used to ensure therebound hammer is positioned for optimum performance.Position the hammer not less than one diameter from the edgeof the specimen.9.4 For tests conducted in situ on a rock mass, the reboundhammer can be used at any desi
35、red orientation provided theplunger strikes perpendicular to the surface tested. The resultsare corrected to a horizontal or vertical position using thecorrection curves provided by the manufacturer.9.5 Before conducting the tests, ensure the hammer is at thesame temperature as the test specimens by
36、 exposing it to theambient environmental conditions of the test area (indoors oroutdoors) for at least 2 h.9.6 Compress the hammer spring by gradually depressingthe plunger until the hammer is triggered and impact occurs.D58730529.7 Read and record the height of the plunger rebound to thenearest who
37、le number, as measured on an arbitrary scale of 10to 100 divisions located on the side of the hammer, beforerestoring the piston to its original extension. Repeat thisprocedure at ten representative locations on the specimen. Testlocations shall be separated by at least the diameter of thepiston and
38、 only one test may be taken at any one point.9.8 If a specimen breaks during rebound testing, energy isabsorbed during breakage and, consequently, the reboundreading will be lower than had it not broken. Any individualimpact test that causes cracking or any other visible failureshall cause that test
39、 and the specimen to be rejected.9.9 Some factors that may affect the results of the testinclude:9.9.1 Rock at 0 C or less may exhibit very high reboundvalues.9.9.2 Temperature of the rebound hammer itself may affectthe rebound number. The hammer and materials to be testedshould be at the same tempe
40、rature.9.9.3 For readings to be compared, the direction of impact,horizontal, upward, downward, and so forth, must be the same.9.9.4 Different hammers of the same nominal design maygive rebound numbers differing from one to three units andtherefore, tests should be made with the same hammer in order
41、to compare results. If more than one hammer is to be used, asufficient number of tests must be made on typical rocksurfaces to determine the magnitude of the differences to beexpected.10. Calculation10.1 Using the data from the ten readings obtained in 9.7,discard readings differing from the average
42、 of ten readings bymore than seven units and determine the average of theremaining readings. To calculate the rebound hardness number(HR) of the tested rock material, multiply this average by thecorrection factor determined in 8.1.2 and record the results tothe nearest whole number.11. Report11.1 Re
43、port the following minimum information for eachspecimen or test area:11.1.1 Source of samples, including geographic location;boring number, depth, orientation, and stationing; and rocktype,11.1.2 Weathering and alteration condition of samples, par-ticularly when sampling a surface outcrop,11.1.3 Typ
44、e of specimen (core, block, or in situ); size andshape of specimen; and, if block type, whether cut or blasted,11.1.4 Date of sampling and date of testing,11.1.5 Storage conditions of samples (for example, expo-sure to temperature extremes, air drying, and moisturechanges),11.1.6 Type and model numb
45、er of hammer,11.1.7 Orientation of the plunger axis during the test,11.1.8 Method of securing the sample (for example,V-block, or clamps),11.1.9 Number of tests conducted,11.1.10 Temperature of site at time of test, and11.1.11 The individual and average values of hammer re-bound, the value of the co
46、rrection factor, and the reboundhardness number, HR(obtained in 10.1).12. Precision and Bias12.1 PrecisionNo data exist to determine the precision ofthis test method in determining rock hardness.12.2 BiasThere is no accepted standard value for HRforany material, therefore bias cannot be determined.1
47、3. Keywords13.1 core; hardness; rock mass; rock; unconfined compres-sive strengthSUMMARY OF CHANGESIn accordance with Committee D18 policy, this section identifies the location of changes to this standard sincethe last edition (00(2005) that may impact the use of the standard.(1) Deleted Test Method
48、 D 2938 in Sections 1.2 and 2.1, andreplaced with Test Method D 7012.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of an
49、y such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time 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 yo
