ASTM C349-2018 Standard Test Method for Compressive Strength of Hydraulic-Cement Mortars (Using Portions of Prisms Broken in Flexure).pdf

1、Designation: C349 18Standard Test Method forCompressive Strength of Hydraulic-Cement Mortars(Using Portions of Prisms Broken in Flexure)1This standard is issued under the fixed designation C349; the number immediately following the designation indicates the year oforiginal adoption or, in the case o

2、f 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 mo

3、rtars, using for thetest specimens portions of prisms made and broken in flexurein accordance with Test Method C348.1.2 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 inSI

4、 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 this

5、standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.(WarningFresh hydraulic cementitious mixtures are causticand may cause chemical burns to skin and tissue uponprolonged exposure.2)1.5 This internatio

6、nal standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Commit

7、tee.2. Referenced Documents2.1 ASTM Standards:3C109/C109M Test Method for Compressive Strength ofHydraulic Cement Mortars (Using 2-in. or 50-mm CubeSpecimens)C125 Terminology Relating to Concrete and Concrete Ag-gregatesC219 Terminology Relating to Hydraulic CementC348 Test Method for Flexural Stren

8、gth of Hydraulic-Cement MortarsC670 Practice for Preparing Precision and Bias Statementsfor Test Methods for Construction MaterialsIEEE/ASTM SI 10 Standard for Use of the InternationalSystem of Units (SI): The Modern Metric System3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in t

9、his test method, referto Terminology C125 and C219.4. Significance and Use4.1 This method provides a means of obtaining compressivestrength values from the same specimens previously used forflexural strength determinations by Test Method C348. Thecompressive strength values are for reference purpose

10、s, and notas substitutes for values obtained by Test Method C109/C109M for cement acceptance.5. Apparatus5.1 Bearing PlatesThe bearing plates shall be 25 mm inthickness and shall be made of a hard metal. The surfaces of thebearing plates that are placed in contact with the specimensshall be 40.0 6 0

11、.1-mm by 50.8-mm rectangles, with the50.8-mm dimension at right angles to the longitudinal axis ofthe prism. The bearing plate surfaces in contact with thespecimen shall have a Rockwell hardness of not less than 60HRC. These surfaces shall not depart from plane surfaces bymore than 0.01 mm when the

12、plates are new and shall bemaintained within a permissible variation of 0.03 mm.5.2 Device for Aligning Bearing PlatesA device for align-ing the bearing plates to ensure the proper location of the upperplate with reference to the lower plate is shown in Fig. 1.Iftheupper bearing plate does not have

13、free movement within thealigning plates, these shall be separated from the bottom plateby insertion of 0.05-mm shims on each side of the bottom1This test method is under the jurisdiction of ASTM Committee C01 on Cementand is the direct responsibility of Subcommittee C01.27 on Strength.Current editio

14、n approved Dec. 1, 2018. Published December 2018. Originallyapproved in 1954. Last previous edition approved in 2014 as C349 14. DOI:10.1520/C0349-18.2See the section on Safety, Manual of Cement Testing, Annual Book of ASTMStandards, Vol 04.01.3For referenced ASTM standards, visit the ASTM website,

15、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.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive,

16、 PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issue

17、d by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1FIG. 1 Bearing Plates and Bearing Plate Aligning Device for Testing 40 by 40 by 160-mm Mortar Prisms as Modified CubesC349 182bearing plate, and the two 6-mm pins in the upper bearing platefiled down just sufficiently to

18、permit free up and downmovement in the slots at the top of the aligning plates.5.3 Testing MachineThe testing machine shall conform tothe requirements prescribed in Test Method C109/C109M,except that the testing machine shall be of the hydraulic type.6. Test Specimens6.1 Both portions from each pris

19、m broken in flexure shall beused for compression testing, except that the broken portions ofprisms selected for the compression test shall have a length ofnot less than 65 mm and shall be free of cracks, chippedsurfaces, or other obvious defects.7. Procedure7.1 Determination of Compressive StrengthD

20、uring theinterval between flexure tests of the prisms and testing thebroken portions as modified cubes, cover the specimens for the24-h test with waterproof plastic and completely immerse allother specimens in water at a temperature of 23 6 2.0C untilthe time of testing. Wipe the specimen to a surfa

21、ce-drycondition, and remove any sand grains or incrustations fromthe faces that will be in contact with the bearing plates of thetesting apparatus. Check these faces by application of astraightedge. If there is appreciable curvature, grind the face orfaces to plane surfaces or discard the specimen (

22、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 plate assembly on top of this pedestal. Ifthe testing machine has no provisions for automatic accuratecentering of a pedestal exactly below the center of it

23、s upperspherical bearing head, a hardened steel cylinder of suitablediameter and height and with parallel plane end faces may beused, provided that the bearing plate assembly is centeredaccurately below the center of the upper bearing head after thespecimen has been placed in proper position in the

24、bearingplate assembly. Apply the specimen aligning guide to theoutside of one of the aligning plates of the bearing plateassembly, with the lugs 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 mold

25、ed andplace it in the device with the bottom as molded in contact withthe aligning lugs, holding the aligning guide against thealigning plate firmly with one hand. Then remove the aligningguide without disturbing the position of the specimen andapply the load in accordance with the Procedure section

26、 of TestMethod C109/C109M. The testing of the broken portions asmodified cubes shall follow breaking in flexure within 10 minfor 24-h specimens 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 modifie

27、d cube that are nottruly plane surfaces. It is essential, therefore, that molds be keptscrupulously clean, as otherwise large irregularities in the surfaces willoccur. Instruments for cleaning molds should always be softer than themetal in the molds to prevent wear. In case grinding of modified cube

28、faces 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 onlymoderate pressure. Since such grinding is tedious for more than a fewthousandths of an inch or hundredth of a millimetre, it is recommendedthat where mor

29、e than this is found necessary, the specimen be discarded.8. Calculation8.1 Record the total maximum load indicated by the testingmachine and calculate the compressive strength in megapascalsto the nearest 0.1 MPa, as follows:Sc5 0.00062P (1)where:Sc= compressive strength, MPa, andP = total maximum

30、load, N.9. Faulty Specimens and Retests9.1 Specimens that are manifestly faulty or that result instrengths differing by more than 10 % from the average valueof all test specimens made from the same sample and tested atthe same period shall not be considered in determining thecompressive strength. Af

31、ter discarding strength values, if lessthan two strength values are left for determining the compres-sive strength at any given period a retest shall be made.NOTE 2Reliable strength results depend upon careful observance ofall of the specified requirements and procedures. Erratic results at a givent

32、est period indicate that some of the requirements and procedures have notbeen carefully observed; for example, those covering the testing of themodified cubes, as prescribed in Sections 6 and 7. Specimens exhibitingoblique fractures on breaking, due to improper centering in the compres-sion machine

33、or to lateral movement of one of the testing machine headsduring loading, will often indicate lower strengths than specimensshowing a normal pyramidal fracture.10. Precision and Bias10.1 PrecisionThe following precision statements are ap-plicable when a test result is the average of compressivestren

34、gth tests of six modified cubes (using portions of prismsbroken in flexure) molded from a single batch of mortar andtested at the same age.NOTE 3The test results used to calculate precision statistics weretaken from tests on Type I, IA, and IS cements tested at 3, 7, and 28 days,and on a Type III ce

35、ment tested at 1, 3, and 7 days.10.1.1 Multilaboratory PrecisionThe multilaboratory co-efficient of variation has been found to be 6.3 %. Therefore,results of properly conducted tests of single batches by twodifferent laboratories should not differ by more than 17.8 % oftheir average (Note 4).NOTE 4

36、These numbers represent, respectively, the (1s%) and (d2s%)limits as described in Practice C670.10.1.2 Single-Laboratory PrecisionThe single-laboratorycoefficient of variation has been found to be 3.5 %. Therefore,results of two properly conducted tests of single batches ofmortar made with the same

37、materials either on the same day orwithin the same week should not differ from each other bymore than 9.9 % of their average (Note 4).10.2 BiasThe procedure in this test method has no biasbecause the value of compressive strength is defined in termsof the test method.11. Keywords11.1 compressive str

38、ength; hydraulic-cement mortar;hydraulic-cement strength; mortar strength; strengthC349 183For additional useful information on details of cement test methods, reference may be made to the “Manual of CementTesting,” which appears in the Annual Book of ASTM Standards Vol 04.01.SUMMARY OF CHANGESCommi

39、ttee C01 has identified the location of selected changes to this standard since the last issue (C349 14)that may impact the use of this standard. (Approved Dec. 1, 2018.)(1) Added Section 3, Terminology, in accordance with ASTMForm and Style.ASTM International takes no position respecting the validi

40、ty 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 riskof infringement of such rights, are entirely their own responsibility.This standard is subjec

41、t 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 Headquarte

42、rs. 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 your views known to the ASTM Committee on Standards, at the address shown below.This standard

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