Designation: D5731 − 08Standard Test Method for Determination of the Point Load Strength Index of Rock and Application to Rock Strength Classifications1 This standard is issued under the fixed designation D5731; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (´) indicates an editorial change since the last revision or reapproval. 1. Scope* 1.9 This standard does not purport to address all of the 1.1 This test method covers the guidelines, requirements, safety concerns, if any, associated with its use. It is the and procedures for determining the point load strength index of responsibility of the user of this standard to establish appro- rock. This is an index test and is intended to be used to classify priate safety and health practices and determine the applica- rock strength. bility of regulatory limitations prior to use. 1.2 Specimens in the form of rock cores, blocks, or irregular 2. Referenced Documents lumps with a test diameter from 30 to 85 mm can be tested by 2.1 ASTM Standards:2 this test method. D653 Terminology Relating to Soil, Rock, and Contained 1.3 This test method can be performed in either the field or Fluids laboratory. The test is typically used in the field because the D2216 Test Methods for Laboratory Determination of Water testing machine is portable, little or minimal specimen prepa- (Moisture) Content of Soil and Rock by Mass ration is required, and specimens can be tested within a short D3740 Practice for Minimum Requirements for Agencies time frame of being collected. Engaged in Testing and/or Inspection of Soil and Rock as 1.4 This test method applies to medium strength rock Used in Engineering Design and Construction (compressive strength over 15 MPa (2200 psi)). D5079 Practices for Preserving and Transporting Rock Core Samples 1.5 This test method does not cover which type of specimen D6026 Practice for Using Significant Digits in Geotechnical should be tested or whether anisotropic factors should be Data considered. The specifics of the point load test program need to D7012 Test Methods for Compressive Strength and Elastic be developed prior to testing and possibly even before sam- Moduli of Intact Rock Core Specimens under Varying pling. Such specifics would be dependent on the intended use States of Stress and Temperatures of the data, as well as possible budgetary constraints and E18 Test Methods for Rockwell Hardness of Metallic Ma- possible other factors, which are outside the scope of this test terials method. E122 Practice for Calculating Sample Size to Estimate, With 1.6 All observed and calculated values shall conform to the Specified Precision, the Average for a Characteristic of a guidelines for significant digits and rounding established in Lot or Process Practice D6026. 2.2 ISRM Standard: Suggested Methods for Determining Point Load Strength3 1.7 The method used to specify how data are collected, calculated, or recorded in this standard is not directly related to 3. Terminology the accuracy to which the data can be applied in design or other uses, or both. How one applies the results obtained using this 3.1 For definitions of terms used in this test method refer to standard is beyond its scope. Terminology D653. 1.8 The values stated in the SI units are to be regarded as 3.2 Definitions of Terms Specific to This Standard: standard. 2 For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at
[email protected]. For Annual Book of ASTM 1 This test method is under the jurisdiction of ASTM Committee D18 on Soil and Standards volume information, refer to the standard’s Document Summary page on Rock and is the direct responsibility of Subcommittee D18.12 on Rock Mechanics. the ASTM website. 3 Current edition approved Jan. 1, 2008. Published February 2008. Originally “Suggested Methods for Determining Point Load Strength”, International approved in 1995. Last previous edition approved in 2007 as D5731 – 07. DOI: Society for Rock Mechanics Commission on Testing Methods, Int. J. Rock. Mech. 10.1520/D5731-08. Min. Sci. and Geomechanical Abstr., Vol 22, No. 2, 1985, pp. 51–60. *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 1 The platens shall be of hard material load strength index of rock specimens and.4 Rock specimens in the form of either core (the diametral during testing. as shown on Fig.3 Load Measuring System: (the irregular lump test) are tested by application of concen. 6.2. 2.2. D5731 − 08 3. it may placed in the test machine be necessary to handle specimens in accordance with Practice 3. as explained in Test Method E18) such as point load strength anisotropy index.3 This test method is performed to determine the point shall meet tangentially. The failure 6. that is.3 D.1 The loading system shall have a loading frame with a 4.3 size-corrected point load strength index— Is(D). Apparatus 3. (BX cores) are not recommended because for smaller diameters the However.2.1 The uniaxial compression test (see Test Method D7012) NOTE 2—It is generally accepted that specimens smaller than 42 mm is used to determine compressive strength of rock specimens. a measuring system for indicating load. No spherical seat expensive laboratory tests.2 mm throughout testing. pages 1-11. 6.. the D5079 and to document moisture conditions in some manner in strength anisotropy index is defined as the ratio of mean Is(D) the data collection.2 The point load strength test is used as an index test for when specimens of irregular geometry are tested. until failure break the specimen). for point load tests. test platens when time it is obtained until the time it is tested. and cost of compressive strength tests. Practice D3740 provides to normalize the value that would have been obtained with a means of evaluating some of those factors. mainte- specimen to an increasingly concentrated load until failure nance or calibrations instructions provided by the manufacturer occurs by splitting the specimen. 2 . P.2.2 The loading capacity shall be sufficient to break the When extensive testing and/or timely information is required largest and strongest specimens to be tested. cut blocks (the block test). Agencies that meet the least ratio of point load strengths values. and so that the platens remain cost effective selection of samples for more precise and coaxial within 60. (required to through a pair of truncated. Point load for preliminary and reconnaissance information. for example a load cell or a trated load through a pair of truncated.4 Truncated. specimen to an increasingly concentrated point load. A common method used is by estimating the uniaxial in the required size range.1 A load measuring system. truncated conical platens. the (Rockwell 58 HRC. applied through coaxial. 6.3 The load frame shall be designed and constructed so Such data can be used to make timely and more informed that it does not permanently distort during repeated applica- decisions during the exploration phases and more efficient and tions of the maximum test load. Significance and Use small and large specimens. and axial tests).2. the dimension of the be highly influenced by how the specimen is treated from the specimen between the opposing conical.2 The point load strength index can be used to classify the platen-to-platen clearance that allows testing of rock specimens rocks.2. and the strength indices on different axes that result in the greatest and suitability of the equipment and facilities used. Engineering condition on the test data minimized.4 uncorrected point load strength index— (Is). strength classification of rock materials. applied platens. the that compliance with Practice D3740 does not in itself assure reliable original point load strength index value multiplied by a factor results. The equipment shall be resistant to shock and 4. 6. The concentrated load is for the particular apparatus being used shall be followed. so that an adjustable distance is available to accommodate both 5. Z.2. values measured perpendicular and parallel to planes of NOTE 1—The quality of the result produced by this standard is weakness. Users of this standard are cautioned 3. Therefore. 5. occurs. it is a time-consuming and expensive test that loading points can not be considered as theoretical “points” in relation to specimen size. The test results should 6. conical platens. tungsten carbide or hardened steel so they remain undamaged 5. conical platens. Summary of Test Method vibration so that the accuracy of readings is not adversely 4. Loading system rigidity is essential to avoid slippage 5. are to not be used for design or analytical purposes.3. that will indicate failure load. when used in the field. to 100 mm. the results can Geology (9). the ratio of greatest to least point load dependent upon the competence of the personnel performing it. or other nonrigid component is permitted in the loading system. criteria of Practice D3740 are generally considered capable of competent and objective testing and sampling. if required. The 60° cone and 5-mm radius spherical platen tip 5. no specimen preparation is required and can therefore be tested shortly after being obtained and any influence of moisture 4 Bieniawski.2 Loading System: load is used to calculate the point load strength index.1 General—A basic point load tester (see Fig. 1975. or irregular lumps 6. 1) consists cator of strength (see 10. and a means for measuring the distance. an indi. Little or hydraulic pressure gage.1) obtained by subjecting a rock of a loading system typically comprised of a loading frame.2 point load strength anisotropy index— Ia(D). be used. this range is between 30 compressive strength. However.4 requires significant specimen preparation and the results may not be available for a long time after the samples are collected. P. The Point Load Test in Geotechnical Practice. Reliable results depend on many factors. 6. between the two platen contact points at the start of testing and after failure.2.1 diameter—D. conical platens. diametral test of diameter (D). Any special operational.1 This index test is performed by subjecting a rock affected by repeated testing. alternative strength of rock is usually an order of magnitude lower than the tests such as the point load test can be used to reduce the time compressive strength of rock. or the maximum opening size of the load frame. Typically. 6.T. 3. and estimated strength. towels. 6. shall be to a preci. etc.3.5 Miscellaneous Items—Depending on the type of interchangeable.4. the system should be capable of using 6. between specimen-platen con- 7. be needed: diamond saw. mechanical or electronic gauge. of specimens for all but the diametral test.4.1 When testing core or block samples at least ten size and strength of specimen that is tested. measure any penetration of the specimen by the point load irrespective of the size and strength of specimen that is tested. an electronic or ver- nier direct reading scale. 6. (with an accuracy of 65 %) each test. conform to requirements 6. the following items may of rock and have the desired reading accuracy.2 Measurements of D shall be to an accuracy of 62 % 7. marking pens.3 The measuring system shall allow a check of the “zero requirements of 6.1 The distance measuring system.4 If required.4.4. The system should conform to the 6. 3 . P. W. irrespective of the 7. Block.4. load measur- samples (core or non core) and the type of specimens to be ing devices in order to be consistent with the estimated strength tested (diametral. test tact points at the start of testing and just prior to failure and direction if rock is aniasotropic. platens during testing.3. and a peak load 6.4 Distance Measuring System: plotting paper.2.3 Failure is often sudden.2 – 6. 1 Example of a Light-Weight Point Load Test Apparatus required to break specimen. pressure relief valve (9). Axial. 6. 6. chisels.2 Measurements of failure load. therefore. D5731 − 08 NOTE 1—Load frame general information (figure 1) Load is applied to the specimens through two standard hardened points (1) Two column fixed crosshead frame (2) Scale (3) Scale pointer (4) Attached by a bolt (5) to the hydraulic pump body (6) Oil filler cap (7) The hydraulic piston assembly incorporated the oil reservoir.2 Sample Size or better of distance between contact points.3.2 and 6. and 6. specimens are selected for the samples.4 An instrument such as a caliper or a steel rule is indicator is required so the failure load can be recorded after required to measure the width.). should connect to the loading frame 7.1 Rock samples are grouped on the basis of rock type. should include a zero adjustment and a means to record or sion of 65 % or better of full-scale load-measuring system. a single acting pump. and a handle (8) Pump handle (8) Pressure release valve (9) Case latched for top cover (10) Digital pressure readout (11) Point load tester top cover(12) FIG. D. Test Samples for measuring the distance. displacement” value when the two platens are in contact and 6.4.3.4.3. block or irregular). and calculate the averages.4 If needed. No. precise classification. the testing determine the sample size.2 Size and Shape—The size and shape requirements for width. and diameter. These lines are used for centering the specimen in the testing 8. Procedure required.3 Water Content—Water content of the specimen can 7. 4 . 32. if needed. 111.. NOTE 3—While there are no established specimen guidelines for grain size versus specimen size this subject is still important and must be 5 Robins. diametral test. preferred test diameter of about 50 mm. P. or irregular lump testing shall conform 8. Practice E122 can be used to more precisely affect the value of the point load strength. sampling plan to block or irregular specimens. maximum aggregate size of 4 be used. specimens shall be free from abrupt irregularities that can generate stress concentrations. 7.2. 2 Truncated. Test Specimens shall be indicated by marking lines on the specimen. however a rock saw or chisels may be required for 9.2.1 Test Diameter—The specimen’s external test diameter machine. axial.1 Marking—The desired test orientation of the specimen 8. D5731 − 08 FIG. 3).2 Diametral Test from the cores by saw-cutting. The Point Load Strength Test for Concrete Cores.3 Samples in the form of core are preferred for a more controlling. Magazine of included in the testing and use of the data. when the core axis is perpendicular to the plane of weakness.2. These lines may also be used as reference lines for measuring 8.4.4 For anisotropic rocks the best results for core samples is should be properly marked and measured as shown in Fig.2 Measuring—Measure each dimension of a specimen with the recommendations shown on Fig. 4. and measurement of water content. or core splitting. Concrete testing using a point Concrete Research.1 Develop a testing plan and. 3. and to ensure proper orientation during testing.4.J. Proper planning of diametral provide specimens for point load testing according to the tests on rock cores can produce suitable lengths of core for following procedures for the specific specimen shape subsequent axial testing provided they are not weakened by the (diametral. Vol.2 When testing irregular-shaped specimens obtained by load tester recommends that a minimum ratio of core diameter to other means at least 20 specimens are selected for the samples. suitable specimens can be obtained 9. 8. June 1980.3 Sample sizes may need to be larger if the rock is anisotropic or heterogeneous. Conical Platen Dimensions for Point Load Ap- paratus 7. 8. This may include the recording. shall not be less than 30 mm and not more than 85 mm with the including any issues involving anisotrophic rocks (see Fig. axial. 8. Therefore. No specimen preparation is 9.5 This ratio may be used until guidelines are developed for rock.4 Marking and Measuring Specimens— The specimens 7. The sides of the at three different places. block. plan shall include how water content will be included in the point load testing program. Otherwise. length. diametral. 7. Ensure that the can be obtained by saw-cutting or chisel-splitting the core distance.2). loading point (see Fig. the loading direction. Suitable specimens platens to make contact along a core diameter. 5(d)).4 are repeated for each (see Fig. D5731 − 08 NOTE 1—Legend: L = distance between contact points and nearest free face. 9. but see rejected if the fracture surface passes through only one platen Fig. D. and (d) the Irregular Lump Test3 FIG. W.3 Determine and record the distances D and L (see Fig. The test should be end faces (in the case of isotropic rock.5 times the core diameter (see Fig. with an accuracy of 65 %. 4(a)).2. 5 and 9.2. 9. Record the specimen width.3 Record the distance.2. and record failure load. FIG. P. 9. 3(b)). perpendicular to specimen of the rock type. between platen contact points 9.1 Core specimens with length/diameter ratio greater 9. 3).3 Axial Test than one are suitable for diametral testing.4 Steadily increase the load such that failure occurs platens to make contact along a line perpendicular to the core within 10 to 60 s.2 Insert a specimen in the test device and close the are suitable for axial testing (see Fig.1 Core specimens with length/diameter ratio of 1⁄3 to 1 9. 5 .1). (b) the Axial Test.2.2. and De = equivalent core diameter (see 10. 9.2 – 9.5 The procedures in 9.2 Insert a specimen in the test machine and close the 9. (c) the Block Test. 4 Anisotropy measurements and testing for maximum and minimum indices 9.3.3.2.2.3. the core axis. 3).5 for anisotropic rock). planned diametral tests (see 9. or by using suitable pieces produced by carefully is at least 0. L. 3 and Fig. between the contact points and the nearest free end sample. 3 Load Configurations and Specimen Shape Requirement for (a) the Diametral Test. The test should 9. 6 Procedure for Graphical Determination of Is(50) from a Set of Results at De Values Other Than 50 mm 3 6 .3.4 Steadily increase the load such that failure occurs 9.2 – 9. (d) in- valid core test.3. The ratio.3 9.5 specimen of the rock type. 3(c) and ( d) are suitable for the block and the loading point (see Fig. D/W.3. The distance L should be at least 0. D5731 − 08 FIG. (b) valid axial tests. and (e) invalid axial test (point load strength index test). 6(e)).3. 30 to 85 mm. P. should be between 1⁄3 and 9.4 Block and Irregular Lump Tests : within 10 to 60 s. preferably close to 1. (c) valid block tests.1 Rock blocks or lumps. FIG.4. 5 Typical Modes of Failure for Valid and Invalid Tests—(a) Valid diametral tests. and of the shape be rejected if the fracture surface passes through only one shown in Fig.5 Procedures 9.4 are repeated for each test 1. irregular lump tests. and record the failure load. 6 If significant platen penetration occurs. with rock quality designations (RQD) and predominance of Nx 9. Calculation chisel-splitting larger samples or specimens if needed. The error 10.2 At the minimum. The angle an unique point load strength value for the rock specimen and between the core axis and the normal to the direction of least one that can be used for purposes of rock strength classifica- strength should preferably not exceed 30°. mm2. it core samples.4 For measurement of the point load strength index (Is) 10. the separation of the loading points. 3(c) and I s 5 P/D e 2 . such as when testing weak sandstones. Is. away from edges and corners (see Fig. Points that preferred.3. the platen contact points (see Fig.3. the dimension D performed using other specimen sizes or shapes.1 When a rock sample is shaly. Most point load strength tests are in fact 9. so that a size correction must be applied. when if the D values for all the specimens are not the same.5 must be D' measured at the instant of failure.1 The point load index.5. a single plane of weakness. N. with load first applied 10. then along the observable planes of weak. P = failure load. as-received.5.3 nor 10. and 9. to obtain possible. tion.2 If the sample consists of core drilled through weakness 10.2.3 Strongest test results are obtained when the core axis irregular lump tests. Is(D). W. schistose. In such cases. calculating point load strength index irrespective of the actual or mode of failure (see Fig. This width.2.4. the core should be drilled in this direction. made perpendicular to the line joining the loading points are not affected by this platen penetration and should be 9. If a log-log plot is always be used as an alternative to the initial value and is used. from: tions that will give the greatest and least strength values.2.4. 9. block. spaced 10.2 The size corrected point load strength index. it should be tested in direc.1 For precise measurements. the relation is a straight line (see Fig. 9.2 Insert a specimen in the testing machine and close the rected point load strength.4.4 is practical (for air-dried. a set of diametral tests may be completed first. 3). of value in the direction of least strength.4 are repeated for each test NOTE 4—If significant platen penetration occurs in the test.2 – 9. when testing that would have been measured by a diametral test with D = 50 for the Is value in the direction of greatest strength.4 The most reliable method of size correction is to test in assuming D to be its initial value is negligible when the the specimen over a range of D or De values and to plot specimen is large or strong. W. example when testing single-sized core at a diameter other than 7 . in D 2e 5 D 3 D' for cores 5 4/π W 3 D' for other shapes (2) general. to be used in calculating point load strength should be the value the size correction described in 10.5. D'. in case of diametral tests on NX. The test should be rejected if the fracture surface passes through only one A = WD = minimum cross-sectional area of a plane through loading point (see examples for other shapes in Fig. the diametral test. mm. or specimen width. follow Test Method D2216 corresponding to D e2 = 2500 mm2 ( De = 50 mm) can be to determine the water content of each rock specimen and obtained by interpolation and use of the size-corrected point report the moisture condition (see Section 11). is used in De2 = D2 for diametral core tests without penetration. is calculated as: platens to make contact with the smallest dimension of the lump or block. perpendicular to the De = equivalent core diameter (see Fig.1 Uncorrected Point Load Strength Index—The uncor- 9. therefore. load strength index calculated as shown in 10. ensure that mm and given the symbol Is(50). that will be smaller than applied. Again. The value of Is(50) 9.5 Procedures 9. 10. and lump tests.3. core diameter = 54 mm and size correction to D = 50 mm is not necessary. The dimension at failure may graphically the relation between P and De. 5 (c).4 or 10. parallel and normal to the planes of anisotropy. 3). water content shall be recorded as 10. D5731 − 08 W. 9.4.2. most reliable method of obtaining Is(50) is to conduct diametral ness.7 Water Content (although they should not be deleted). 7.4 Steadily increase the load such that failure occurs where: within 10 to 60 s. 3.2. block. bedded. 9. The modified values of De can be calculated otherwise observably anisotropic.4.5 If the sample consists of blocks or irregular lumps.2.2. 4).5. P. Measurements of core diameter. 9.7. should be tested as two subsamples. and as a function of De in axial. See Fig.2. the required minimum strength value is obtained tests at or close to D = 50 mm.5. and 9. Record the smallest specimen width.4. and is loading direction. the value of D should be the final value of specimen in the sample. mm2. deviate substantially from the straight line may be disregarded 9.7. is perpendicular to the planes of weakness.2. Similarly.2. and record the failure load. the initial value suggested in 9. Suitable specimens can be obtained by saw-cutting or 10. W. where: 9. 6). MPa (1) (d).3 Record the distance D between platen contact points.5 Anisotropic Rock: D. varies as a function of D in at intervals that will yield pieces that can then be tested axially. etc. De 2 = 4A/π for axial.2 Size Corrected Point Load Index : planes.3. or retained at the original values. ensure that load is a rock specimen is defined in this procedure as the value of Is applied along a single weakness plane.5.3 When a precise rock classification is essential. For example.2. The diameter of 50 mm has the load is applied perpendicular to the direction of least been the preferred diameter since that diameter is associated strength (see Fig.5 When neither 10. If the sides are not parallel. 5(d) or (e). saturated. the perpendicular to. Size correction is then when the platens make contact and are loaded to failure along unnecessary. then calculate W given by: as (W1 + W2)/2 as shown on Fig.4. Is . 9. 9. Other Strength Clas- sifications May be Used. 7 Example of Descriptive Strength Classification and Using a Nomograph to Compute the Point Load Index. size I s ~ 50! 5 F 3 I s (3) correction may be accomplished using the formula: 3 FIG. 50 mm or if only a few small pieces are available). 8 Size Correction Factor Chart 8 . D5731 − 08 FIG. .E. The Point-Load Test in Geotechnical Practice. if known.4 Point Load Strength Anisotropy Index—The strength anisotropy index Ia(50) is defined as the ratio of mean Is(50) values measured perpendicular and parallel to planes of 10. 1965.. only slight error is Is = uncorrected point load strength index from a specimen introduced by using the approximate expression: with a specific test diameter (D). R.5 highest and lowest values are to be deleted and the mean A Bieniawski.4 on Fig. D. 6702. etc. 6.S. 9 Relationship Between Point Load Strength Index and Uniaxial Compressive Strength from 125 Tests On Sandstone. Z.. If significantly fewer specimens are tested. or from the expression: where: F 5 ~ D e /50! 0. Quartzite. MPa K = index to strength conversion factor that depends on where: site-specific correlation between sc and Is for a specific F 5 size correction factor specimen with a test diameter (D). block sample. 96. or 42 (Bx Core) 21 50 23 more. D5731 − 08 The “Size Correction Factor F” can be obtained from the s c 5 K*I s (6) chart in Fig. it should be examined for defects and a strength indices.. Prediction of Compressive 11.1 If site-specific correlation factor “K” is not available.) and. or using the following formula: 11. how collected (drill hole. U.5.1 Source of sample including project name.V.2.1 A typical report (example shown in Fig. that is. Geology (9) 1-11. F 5 =~ D e /50! (5) 10. Invest. Engineering calculated from those remaining.2. 9. instead of using the procedure outlined in 10. See Fig.1. storage (curatorial history) environment.3. valid tests.L. location.5.3.45 (4) sc = uniaxial compressive strength.3.3 Mean Value Calculation: TABLE 1 Generalized Index to Strength Conversion Factor (K) 10. Fisher. 10.5 (Ex Core) 18 10. the ratio of greatest to least point load under the average. and calculating the mean of the remaining 54 (Nx Core) 24 values. Report estimated uniaxial compressive strength can be obtained by using Fig. as defined in 10. Marikana Norite.1 Mean values of Is(50). MPa and For tests near the standard 50-mm size.T. 10. 8. 10. the generalized values may be used in Table 1. D. Strength of Rock from Other Rock Properties. 10) may include the following: 6 D’Andrea. only the 60 24.. 21.2 If any specimen in a rock type gives a value 20 % weakness. are to be forA used when classifying samples with regard to their point load Core Size. The location may be FIG. mm Value of “K” (Generalized) strength and point load strength anisotropy indices. Bureau of Mines Rep.2 The mean value of Is(50) is to be calculated by 30 19 deleting the two highest and two lowest values from the ten.5 Estimation of Uniaxial Compressive Strength—The 11. decision made on the validity of the results. for Nx core. and Fogelson. and Belfast Norite6 9 . laboratory air dry. such as. men preparation. a general indication of the moisture 11.3 Date and personnel involved with sampling. condition of test specimens at the time of testing. weakness or anisotrophy directions).1. 11. D5731 − 08 FIG. or both.1.1.1.1. and location and orientation of discontinuities.10 The number of specimens tested and how prepared.4 Test apparatus used.1. speci.8 The distance “D” or D'.6 Average thickness and average diameter of the test ent weakness planes. Is(50) point load strength index values. such as. 10 . or large specimen.7 The maximum applied load “ P”. inclusions. In some (D=50 mm). schistosity. and calibrations.1. appar. if required.1. model number. 11.1. especially where the results are sensitive to water from the collar of the hole. and testing. 11. or oven dry.1.5 As a minimum. as received.11 The calculated uncorrected ( Is) and corrected saturated.2 Physical description of sample including rock type as determined in accordance with Test Method D2216. content. 11. 11. 10 Test Record Example3 specified in terms of borehole number and depth of specimen cases. if any. 11. bedding planes. 11. it may be necessary to report the actual water content 11.9 Direction of loading (parallel to or normal to plane of 11. (16) Section 8. 7 added. 5 corrected. (27) 10.3. rock. (2) Revised Section 1.1. (Approved February 1. Precision and Bias method.13 The calculated value of strength anisotropy index due to specimen variation as to operator or testing variation. and Subcommittee D18. 2008.2 heading revised. sections.2. 1 replaced with newer version of the apparatus. (28) 11 revised. and 6. bias cannot be determined.1.4.1.1 revised.5. (4) Revised Section 1. and 7. (22) Eq 1 revised.) (1) Change in title to include Rock Strength Classifications.4. (21) 9. (2) Eq 6 was corrected to have symbols to be universal with the literature and with other ASTM standards. 2007. (3) Added Sections 1. The index to strength factor symbol was changed from C to K to be consistent with the literature.4.4.1 were added.2. Keywords physical properties have not been produced for testing. (34) 13 revised. (Approved January 1.1. (32) Fig. axial Compressive Strength and the figure number was cor- (10) Revised 6. Subcommittee D18. (6) Added E122 to 2.2. problem and would allow for development of a valid precision graphs of the tested specimens before and after the test.1 and 9. point load. multiple specimens that have uniform 13. (19) Sections 8. (26) Section 10.2 added. (7) Terms added to Section 3.2 expanded. (24) 10.12 The estimated value of uniaxial compressive tested.2 and 1.2 clarified.2.2. (33) Fig. (8) Revised 5.5 Compressive Strength was changed to Uni- (9) Fig. 3 notation revised.4 (29) Fig. 7. rock specimens that would yield the same test results have not been classification SUMMARY OF CHANGES Committee D18 has identified the location of selected changes to this standard since the last issue (D5731 – 07) that may impact the use of this standard.1 Precision—Due to the nature of rock materials tested by this test method.2. 4 added. (3) Fig. (20) 9. (17) Added Note 3. (15) Added Sections 7.3 revised. rected to the correct figure number.1.1. D5731 − 08 11.2 – 5.4. (Ia(50)).1 compressive strength.14 Type and location of failure. 2 title revised. (12) Updated Sections 6. (23) 10.1. 10 expanded.) (1) Section 8.2 Bias—There is no accepted reference value for this test 12. (35) Table 1 title changed and in-text reference added.5.3.12 cannot determine the variation strength (σc) and the strength classification.3.12 welcomes proposals to resolve this 11. including any photo.3.5 were revised. and 6. 6. index test. 6. 11 . (25) 10.5. (14) Changed previous Section 7 on Specimens into two (30) Fig.2 expanded. (18) Section 8.2. (5) Added Section 1. 7 and 8. 12.4.4. (31) Fig.2.3. therefore.4 revised. Committee D18 has identified the location of selected changes to this standard since the last issue (D5731 – 05) that may impact the use of this standard. statement.7. (11) Note 2 was added.4. (13) Added reference to Bieniawski.4. 8. 12. and 9. between tests since any variation observed is just as likely to be 11. 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