1、Designation: C 349 08Standard Test Method forCompressive Strength of Hydraulic-Cement Mortars(Using Portions of Prisms Broken in Flexure)1This standard is issued under the fixed designation C 349; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、 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 determination of the com-pressive strength of hydraulic-cement
3、mortars, using for thetest specimens portions of prisms made and broken in flexurein accordance with Test Method C 348.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 Values in SI units shall be obtained by measurement i
4、nSI units or by appropriate conversion, using the Rules forConversion and rounding given in Standard IEEE/ASTM SI10, of measurements made in other units.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of th
5、is standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. (WarningFreshhydraulic cementitious mixtures are caustic and may causechemical burns to skin and tissue upon prolonged exposure.2)2. Referenced Documents2.1 ASTM
6、 Standards:3C 109/C 109M Test Method for Compressive Strength ofHydraulic Cement Mortars (Using 2-in. or 50-mm CubeSpecimens)C 348 Test Method for Flexural Strength of Hydraulic-Cement MortarsC 670 Practice for Preparing Precision and Bias Statementsfor Test Methods for Construction MaterialsIEEE/AS
7、TM SI 10 Standard for Use of the InternationalSystem of Units (SI): The Modern Metric System3. Significance and Use3.1 This method provides a means of obtaining compressivestrength values from the same specimens previously used forflexural strength determinations by Test Method C 348. Thecompressive
8、 strength values are for reference purposes, and notas substitutes for values obtained by Test Method C 109/C 109M for cement acceptance.4. Apparatus4.1 Bearing PlatesThe bearing plates shall be not lessthan 25 mm in thickness and shall be made of a hard metal. Thesurfaces of the bearing plates that
9、 are placed in contact with thespecimens shall be 40.0 6 0.1-mm by 50.8-mm rectangles,with the 50.8-mm dimension at right angles to the longitudinalaxis of the prism. The bearing plate surfaces in contact with thespecimen shall have a Rockwell hardness of not less than 60HRC. These surfaces shall no
10、t depart from plane surfaces bymore than 0.01 mm when the plates are new and shall bemaintained within a permissible variation of 0.03 mm.4.2 Device for Aligning Bearing PlatesA device foraligning the bearing plates to ensure the proper location of theupper plate with reference to the lower plate is
11、 shown in Fig.1. If the upper bearing plate does not have free movementwithin the aligning plates, these shall be separated from thebottom plate by insertion of 0.05-mm shims on each side of thebottom bearing plate, and the two 6-mm pins in the upperbearing plate filed down just sufficiently to perm
12、it free up anddown movement in the slots at the top of the aligning plates.4.3 Testing MachineThe testing machine shall conform tothe requirements prescribed in Test Method C 109/C 109M,except that the testing machine shall be of the hydraulic type.5. Test Specimens5.1 Both portions from each prism
13、broken in flexure shall beused for compression testing, except that the broken portions ofprisms selected for the compression test shall have a length of1This test method is under the jurisdiction of ASTM Committee C01 on Cementand is the direct responsibility of Subcommittee C01.27 on Strength.Curr
14、ent edition approved Dec. 1, 2008. Published January 2009. Originallyapproved in 1954. Last previous edition approved in 2002 as C 349 02.2See the section on Safety, Manual of Cement Testing, Annual Book of ASTMStandards, Vol 04.01.3For referenced ASTM standards, visit the ASTM website, www.astm.org
15、, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page 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 C7
16、00, West Conshohocken, PA 19428-2959, United States.SI Equivalentsin.1321451638 0.46212916583478 11116 134 22116 212 3mm 0.8 6.4 7.9 9.5 11.7 13 14.3 16 19 22.2 25 27 44.5 51 52.4 64 76FIG. 1 Bearing Plates and Bearing Plate Aligning Device for Testing 40 by 40 by 160-mm Mortar Prisms as Modified Cu
17、besC349082not less than 65 mm and shall be free of cracks, chippedsurfaces, or other obvious defects.6. Procedure6.1 Determination of Compressive StrengthDuring theinterval between flexure tests of the prisms and testing thebroken portions as modified cubes, cover the specimens for the24-h test with
18、 waterproof plastic and completely immerse allother specimens in water at a temperature of 23 6 2.0 C untilthe time of testing. Wipe the specimen to a surface-drycondition, and remove any sand grains or incrustations fromthe faces that will be in contact with the bearing plates of thetesting apparat
19、us. Check these faces by application of astraightedge. If there is appreciable curvature, grind the face orfaces to plane surfaces or discard the specimen (Note 1).Center the pedestal usually provided for breaking 50 by100-mm cylinders on the base bearing block of the machine,and center the bearing
20、plate assembly on top of this pedestal. Ifthe testing machine has no provisions for automatic accuratecentering of a pedestal exactly below the center of its upperspherical bearing head, a hardened steel cylinder of suitablediameter and height and with parallel plane end faces may beused, provided t
21、hat the bearing plate assembly is centeredaccurately below the center of the upper bearing head after thespecimen has been placed in proper position in the bearingplate assembly. Apply the specimen aligning guide to theoutside of one of the aligning plates of the bearing plateassembly, with the lugs
22、 at each end resting on or slightly abovethe edge of the bearing face of the bottom plate. Turn thespecimen on its side with respect to its position as molded andplace it in the device with the bottom as molded in contact withthe aligning lugs, holding the aligning guide against thealigning plate fi
23、rmly with one hand. Then remove the aligningguide without disturbing the position of the specimen andapply the load in accordance with the Procedure section of TestMethod C 109/C 109M. The testing of the broken portions asmodified cubes shall follow breaking in flexure within 10 minfor 24-h specimen
24、s and within 30 min for all other specimens.NOTE 1Modified Cube FacesResults much lower than the truestrength will be obtained by loading faces of the modified cube that are nottruly plane surfaces. It is essential, therefore, that molds be keptscrupulously clean, as otherwise large irregularities i
25、n the surfaces willoccur. Instruments for cleaning molds should always be softer than themetal in the molds to prevent wear. In case grinding of modified cubefaces is necessary, it can be accomplished best by rubbing the specimen ona sheet of fine emery paper or cloth glued to a plane surface, using
26、 onlymoderate pressure. Since such grinding is tedious for more than a fewthousandths of an inch or hundredth of a millimetre, it is recommendedthat where more than this is found necessary, the specimen be discarded.7. Calculation7.1 Record the total maximum load indicated by the testingmachine and
27、calculate the compressive strength in megapascalsto the nearest 0.1 MPa, as follows:Sc5 0.00062 P (1)where:Sc= compressive strength, MPa, andP = total maximum load, N.8. Faulty Specimens and Retests8.1 Specimens that are manifestly faulty or that result instrengths differing by more than 10 % from t
28、he average valueof all test specimens made from the same sample and tested atthe same period shall not be considered in determining thecompressive strength. After discarding strength values, if lessthan two strength values are left for determining the compres-sive strength at any given period a rete
29、st shall be made.NOTE 2Reliable strength results depend upon careful observance ofall of the specified requirements and procedures. Erratic results at a giventest period indicate that some of the requirements and procedures have notbeen carefully observed; for example, those covering the testing of
30、themodified cubes, as prescribed in Sections 5 and 6. Specimens exhibitingoblique fractures on breaking, due to improper centering in the compres-sion machine or to lateral movement of one of the testing machine headsduring loading, will often indicate lower strengths than specimensshowing a normal
31、pyramidal fracture.9. Precision and Bias9.1 PrecisionThe following precision statements are ap-plicable when a test result is the average of compressivestrength tests of six modified cubes (using portions of prismsbroken in flexure) molded from a single batch of mortar andtested at the same age. The
32、y are applicable to mortars madewith Type I, IA, IS, or III cement tested at 3, 7, or 28 days (1,3, or 7 days for Type III cement).9.1.1 Multilaboratory PrecisionThe multilaboratory coef-ficient of variation has been found to be 6.3 %. Therefore,results of properly conducted tests of single batches
33、by twodifferent laboratories should not differ by more than 17.8 % oftheir average (Note 3).NOTE 3These numbers represent, respectively, the (1s%) and (d2s%)limits as described in Practice C 670.9.1.2 Single-Laboratory PrecisionThe single-laboratorycoefficient of variation has been found to be 3.5 %
34、. Therefore,results of two properly conducted tests of single batches ofmortar made with the same materials either on the same day orwithin the same week should not differ from each other bymore than 9.9 % of their average (Note 3).9.2 BiasThe procedure in this test method has no biasbecause the val
35、ue of compressive strength is defined in termsof the test method.10. Keywords10.1 compressive strength; hydraulic-cement mortar;hydraulic-cement strength; mortar strength; strengthC349083For additional useful information on details of cement test methods, reference may be made to the “Manual of Ceme
36、nt Testing,” whichappears in the Annual Book of ASTM Standards Vol 04.01.SUMMARY OF CHANGESCommittee C01 has identified the location of selected changes to this test method since the last issue,C 349 02, that may impact the use of this test method. (Approved December 1, 2008)(1) Revised 1.2, 3.1, an
37、d 6.1 to remove informational units.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 any such patent rights, and the ris
38、kof 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 thi
39、s 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 your comments have not received a fair hearing you shouldmake
40、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 C700, 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).C349084
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