ASTM C496 C496M-2011 Standard Test Method for Splitting Tensile Strength of Cylindrical Concrete Specimens《圆柱形混凝土试样抗开裂拉力强度的标准试验方法》.pdf

1、Designation: C496/C496M 11Standard Test Method forSplitting Tensile Strength of Cylindrical ConcreteSpecimens1This standard is issued under the fixed designation C496/C496M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, the year

2、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.This standard has been approved for use by agencies of the Department of Defense.1. Scope*1.1 This test method covers the deter

3、mination of the split-ting tensile strength of cylindrical concrete specimens, such asmolded cylinders and drilled cores.1.2 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eac

4、hsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.3 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 esta

5、blish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.1.4 The text of this standard references notes that provideexplanatory material. These notes shall not be considered asrequirements of the standard.2. Referenced Documents2.1 ASTM S

6、tandards:2C31/C31M Practice for Making and Curing Concrete TestSpecimens in the FieldC39/C39M Test Method for Compressive Strength of Cy-lindrical Concrete SpecimensC42/C42M Test Method for Obtaining and Testing DrilledCores and Sawed Beams of ConcreteC192/C192M Practice for Making and Curing Concre

7、teTest Specimens in the LaboratoryC670 Practice for Preparing Precision and Bias Statementsfor Test Methods for Construction Materials3. Summary of Test Method3.1 This test method consists of applying a diametralcompressive force along the length of a cylindrical concretespecimen at a rate that is w

8、ithin a prescribed range until failureoccurs. This loading induces tensile stresses on the planecontaining the applied load and relatively high compressivestresses in the area immediately around the applied load.Tensile failure occurs rather than compressive failure becausethe areas of load applicat

9、ion are in a state of triaxial compres-sion, thereby allowing them to withstand much higher com-pressive stresses than would be indicated by a uniaxial com-pressive strength test result.3.2 Thin, plywood bearing strips are used to distribute theload applied along the length of the cylinder.3.3 The m

10、aximum load sustained by the specimen is dividedby appropriate geometrical factors to obtain the splitting tensilestrength.4. Significance and Use4.1 Splitting tensile strength is generally greater than directtensile strength and lower than flexural strength (modulus ofrupture).4.2 Splitting tensile

11、 strength is used in the design ofstructural lightweight concrete members to evaluate the shearresistance provided by concrete and to determine the develop-ment length of reinforcement.5. Apparatus5.1 Testing MachineThe testing machine shall conform tothe requirements of Test Method C39/C39M and be

12、of a typewith sufficient capacity that will provide the rate of loadingprescribed in 7.5.5.2 Supplementary Bearing Bar or PlateIf the diameter orthe largest dimension of the upper bearing face or the lowerbearing block is less than the length of the cylinder to be tested,a supplementary bearing bar

13、or plate of machined steel shall be1This test method is under the jurisdiction of ASTM Committee C09 onConcrete and Concrete Aggregates and is the direct responsibility of SubcommitteeC09.61 on Testing for Strength.Current edition approved July 1, 2011. Published August 2011. Originallyapproved in 1

14、962. Last previous edition approved in 2004 as C496041. DOI:10.1520/C0496_C0496M-11.2For 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 p

15、age onthe ASTM website.1*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.used. The surfaces of the bar or plate shall be machined towithin 6 0.025 mm 6 0.001 in. of plan

16、eness, as measured onany line of contact of the bearing area. It shall have a width ofat least 50 mm 2 in., and a thickness not less than the distancefrom the edge of the spherical or rectangular bearing block tothe end of the cylinder. The bar or plate shall be used in suchmanner that the load will

17、 be applied over the entire length ofthe specimen.5.3 Bearing StripsTwo bearing strips of nominal 3.0 mm18 in. thick plywood, free of imperfections, approximately 25mm 1 in. wide, and of a length equal to, or slightly longerthan, that of the specimen shall be provided for each specimen.The bearing s

18、trips shall be placed between the specimen andboth the upper and lower bearing blocks of the testing machineor between the specimen and supplemental bars or plates, whenused (see 5.2). Bearing strips shall not be reused.6. Test Specimens6.1 The test specimens shall conform to the size, molding,and c

19、uring requirements set forth in either Practice C31/C31M(field specimens) or Practice C192/C192M (laboratory speci-mens). Drilled cores shall conform to the size and moisture-conditioning requirements set forth in Test Method C42/C42M.Moist-cured specimens, during the period between their re-moval f

20、rom the curing environment and testing, shall be keptmoist by a wet burlap or blanket covering, and shall be testedin a moist condition as soon as practicable.6.2 The following curing procedure shall be used for evalu-ations of light-weight concrete: specimens tested at 28 daysshall be in an air-dry

21、 condition after 7 days moist curingfollowed by 21 days drying at 23.0 6 2.0C 73.5 6 3.5F and50 6 5 % relative humidity.7. Procedure7.1 MarkingDraw diametral lines on each end of thespecimen using a suitable device that will ensure that they arein the same axial plane (see Fig. 1, Fig. 2 and Note 1)

22、, or as analternative, use the aligning jig shown in Fig. 3 (Note 2).NOTE 1Figs. 1 and 2 show a suitable device for drawing diametrallines on each end of a 150 mm 3 300 mm 6 in. 3 12 in. cylinder in thesame axial plane. The device consists of three parts as follows:(1) A length of 100-mm 4-in. steel

23、 channel, the flanges of which havebeen machined flat,(2) A section, part a, that is grooved to fit smoothly over the flanges ofthe channel and that includes cap screws for positioning the verticalmember of the assembly, and(3) A vertical bar, part b, for guiding a pencil or marker,The assembly (par

24、t a and part b) is not fastened to the channel and ispositioned at either end of the cylinder without disturbing the position ofthe specimen when marking the diametral lines.NOTE 2Fig. 4 is a detailed drawing of the aligning jig shown in Fig.3 for achieving the same purpose as marking the diametral

25、lines. Thedevice consists of:(1) A base for holding the lower bearing strip and cylinder,(2) A supplementary bearing bar conforming to the requirements inSection 5 as to critical dimensions and planeness, and(3) Two uprights to serve for positioning the test cylinder, bearingstrips, and supplementar

26、y bearing bar.7.2 MeasurementsDetermine the diameter of the testspecimen to the nearest 0.25 mm 0.01 in. by averaging threediameters measured near the ends and the middle of thespecimen and lying in the plane containing the lines marked onthe two ends. Determine the length of the specimen to thenear

27、est 2 mm 0.1 in. by averaging at least two lengthmeasurements taken in the plane containing the lines markedon the two ends.FIG. 1 General Views of a Suitable Apparatus for Marking End Diameters Used for Alignment of Specimen in Testing MachineC496/C496M 1127.3 Positioning Using Marked Diametral Lin

28、esCenterone of the plywood strips along the center of the lower bearingblock. Place the specimen on the plywood strip and align sothat the lines marked on the ends of the specimen are verticaland centered over the plywood strip. Place a second plywoodstrip lengthwise on the cylinder, centered on the

29、 lines markedon the ends of the cylinder. Position the assembly to ensure thefollowing conditions:7.3.1 The projection of the plane of the two lines marked onthe ends of the specimen intersects the center of the upperbearing plate, and7.3.2 The supplementary bearing bar or plate, when used,and the c

30、enter of the specimen are directly beneath the centerof thrust of the spherical bearing block (see Fig. 5).7.4 Positioning by Use of Aligning JigPosition the bear-ing strips, test cylinder, and supplementary bearing bar bymeans of the aligning jig as illustrated in Fig. 3 and center thejig so that t

31、he supplementary bearing bar and the center of thespecimen are directly beneath the center of thrust of thespherical bearing block.7.5 Rate of LoadingApply the load continuously andwithout shock, at a constant rate within the range 0.7 to 1.4MPa/min 100 to 200 psi/min splitting tensile stress untilf

32、ailure of the specimen (Note 3). Record the maximum appliedload indicated by the testing machine at failure. Note the typeof failure and the appearance of the concrete.NOTE 3The relationship between splitting tensile stress and appliedload is shown in Section 8. The required loading range in splitti

33、ng tensilestress corresponds to applied total load in the range of 50 to 100 kN/min11 300 to 22 600 lbf/min for 150 by 300-mm 6 by 12-in. cylinders.FIG. 2 Detailed Plans for a Suitable Apparatus for Marking End Diameters Used for Aligning the SpecimenFIG. 3 Jig for Aligning Concrete Cylinder and Bea

34、ring StripsC496/C496M 1138. Calculation8.1 Calculate the splitting tensile strength of the specimenas follows:T 5 2P/pld (1)where:T = splitting tensile strength, MPa psi,P = maximum applied load indicated by the testing ma-chine, N lbf,FIG. 4 Detailed Plans for a Suitable Aligning Jig for 150 3 300m

35、m63 12 in. SpecimenFIG. 5 Specimen Positioned in a Testing Machine for Determination of Splitting Tensile StrengthC496/C496M 114l = length, mm in., andd = diameter, mm in.9. Report9.1 Report the following information:9.1.1 Identification number,9.1.2 Diameter and length, in. mm,9.1.3 Maximum load, l

36、bf N,9.1.4 Splitting tensile strength calculated to the nearest 0.05MPa 5 psi,9.1.5 Estimated proportion of coarse aggregate fracturedduring test,9.1.6 Age of specimen,9.1.7 Curing history,9.1.8 Defects in specimen,9.1.9 Type of fracture, and9.1.10 Type of specimen.10. Precision and Bias10.1 Precisi

37、onAn interlaboratory study of this testmethod has not been performed. Available research data,3however, suggests that the within batch coefficient of variationis 5 % (see Note 4) for 150 3 300-mm 6 3 12-in. cylindricalspecimens with an average splitting tensile strength of 2.8 MPa405 psi. Results of

38、 two properly conducted tests on the samematerial, therefore, should not differ by more than 14 % (seeNote 4) of their average for splitting tensile strengths of about2.8 MPa 400 psi.NOTE 4These numbers represent, respectively, the (1s %) and(d2s %) limits as defined in Practice C670.10.2 BiasThe te

39、st method has no bias because the split-ting tensile strength can be defined only in terms of this testmethod.11. Keywords11.1 cylindrical concrete specimens; splitting tension; ten-sile strengthSUMMARY OF CHANGESCommittee C09 has identified the location of selected changes to this test method since

40、 the last issue,C496041, that may impact the use of this test method. (Approved July 1, 2011)(1) Reversed the order of units in the test method so that SIunits appear first.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentione

41、din this standard. Users of this standard are expressly advised that determination of the validity of any 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

42、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

43、theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C

44、700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).3Wright, P. J. F., “Comments on an Indirect Tensile Test on Concrete Cylinders,”Magazine of Concrete Research, Vol 7, No. 20, July 1955, pp. 8795.C496/C496M 115