ASTM_D_5731_-_08.pdf

Designation:D573108Standard Test Method forDetermination of the Point Load Strength Index of Rock andApplication to Rock Strength Classifications1This standard is issued under the fixed designation D5731;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.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 guidelines,requirements,and procedures for determining the point load strength index ofrock.This is an index test and is intended to be used to classifyrock strength.1.2 Specimens in the form of rock cores,blocks,or irregularlumps with a test diameter from 30 to 85 mm can be tested bythis test method.1.3 This test method can be performed in either the field orlaboratory.The test is typically used in the field because thetesting machine is portable,little or minimal specimen prepa-ration is required,and specimens can be tested within a shorttime frame of being collected.1.4 This test method applies to medium strength rock(compressive strength over 15 MPa(2200 psi).1.5 This test method does not cover which type of specimenshould be tested or whether anisotropic factors should beconsidered.The specifics of the point load test program need tobe developed prior to testing and possibly even before sam-pling.Such specifics would be dependent on the intended useof the data,as well as possible budgetary constraints andpossible other factors,which are outside the scope of this testmethod.1.6 All observed and calculated values shall conform to theguidelines for significant digits and rounding established inPractice D6026.1.7 The method used to specify how data are collected,calculated,or recorded in this standard is not directly related tothe accuracy to which the data can be applied in design or otheruses,or both.How one applies the results obtained using thisstandard is beyond its scope.1.8 The values stated in the SI units are to be regarded asstandard.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 of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil,Rock,and ContainedFluidsD2216 Test Methods for Laboratory Determination 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 ConstructionD5079 Practices for Preserving and Transporting Rock CoreSamplesD6026 Practice for Using Significant Digits in GeotechnicalDataD7012 Test Methods for Compressive Strength and ElasticModuli of Intact Rock Core Specimens under VaryingStates of Stress and TemperaturesE18 Test Methods for Rockwell Hardness of Metallic Ma-terialsE122 Practice for Calculating Sample Size to Estimate,WithSpecified Precision,the Average for a Characteristic of aLot or Process2.2 ISRM Standard:Suggested Methods for Determining Point Load Strength33.Terminology3.1 For definitions of terms used in this test method refer toTerminology D653.3.2 Definitions of Terms Specific to This Standard: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 Jan.1,2008.Published February 2008.Originallyapproved in 1995.Last previous edition approved in 2007 as D5731 07.DOI:10.1520/D5731-08.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3“Suggested Methods for Determining Point Load Strength”,InternationalSociety for Rock Mechanics Commission on Testing Methods,Int.J.Rock.Mech.Min.Sci.and Geomechanical Abstr.,Vol 22,No.2,1985,pp.5160.*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 States1 3.2.1 diameterD,for point load tests,the dimension of thespecimen between the opposing conical,test platens whenplaced in the test machine3.2.2 point load strength anisotropy index Ia(D),thestrength anisotropy index is defined as the ratio of mean Is(D)values measured perpendicular and parallel to planes ofweakness,that is,the ratio of greatest to least point loadstrength indices on different axes that result in the greatest andleast ratio of point load strengths values.3.2.3 size-corrected point load strength index Is(D),theoriginal point load strength index value multiplied by a factorto normalize the value that would have been obtained withdiametral test o