ASTM_C_348_-_14.pdf

Designation:C34814Standard Test Method forFlexural Strength of Hydraulic-Cement Mortars1This standard is issued under the fixed designation C348;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 determination of the flexuralstrength of hydraulic-cement mortars.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 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 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 Standards:3C109/C109M Test Method for Compressive Strength ofHydraulic Cement Mortars(Using 2-in.or 50-mm CubeSpecimens)C230/C230M Specification for Flow Table for Use in Testsof Hydraulic CementC305 Practice for Mechanical Mixing of Hydraulic CementPastes and Mortars of Plastic ConsistencyC349 Test Method for Compressive Strength of Hydraulic-Cement Mortars(Using Portions of Prisms Broken inFlexure)C670 Practice for Preparing Precision and Bias Statementsfor Test Methods for Construction MaterialsC778 Specification for SandC1005 Specification for Reference Masses and Devices forDetermining Mass and Volume for Use in the PhysicalTesting of Hydraulic CementsC1437 Test Method for Flow of Hydraulic Cement MortarIEEE/ASTM SI 10 Standard for Use of the InternationalSystem of Units(SI):The Modern Metric System3.Summary of Test Method3.1 The test mortar used consists of 1 part cement and 2.75parts of sand proportion by mass.Portland or air-entrainingportland cements are mixed at specified water-cement ratios.Water content of other cements is that sufficient to obtain aflow of 110 6 5%with 25 drops of the flow table.Test prisms,40 by 40 by 160-mm,are molded by tamping in two layers.Prisms are cured one day in the molds and stripped until testedby center point loading.4.Significance and Use4.1 This test method provides a means for determining theflexural strength of hydraulic cement mortars.Portions of themortar prisms tested in flexure according to this test methodmay be used for the determination of compressive strength inaccordance with Test Method C349.4.2 The values are determined from this test method forresearch or reference purposes only and are not used fordetermining compliance with specification requirements.5.Apparatus5.1 Weights,Weighing Devices and Glass Graduates,shallconform to the requirements of Specification C1005.Thebalance shall be evaluated for precision and accuracy at2000 g.5.2 Mixer,Bowl and Paddle,an electrically driven mechani-cal mixer of the type equipped with paddle and mixing bowl,as specified in the Apparatus Section of Practice C305.5.3 Flow Table and Flow Mold,shall conform to Specifica-tion C230/C230M.5.4 Specimen MoldsMolds for the 40 by 40 by 160-mmprism specimens shall be triple-gang molds and shall be sodesigned that the specimens will be molded with their longi-tudinal axes in a horizontal position.The molds shall be made1This test method is under the jurisdiction of ASTM Committee C01 on Cementand is the direct responsibility of Subcommittee C01.27 on Strength.Current edition approved Dec.1,2014.Published December 2014.Originallyapproved in 1954.Last previous edition approved in 2008 as C348 08.DOI:10.1520/C0348-14.2See 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,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,PO Box C700,West Conshohocken,PA 19428-2959.United States1 of a hard metal,not attacked by cement mortar,and with aRockwell hardness of not less than HRB 55.The parts of themolds shall be matchmarked and,when assembled,shall betight-fitting and positively held together.The sides of the moldsshall be sufficiently rigid to prevent spreading or warping.Theinterior faces of the molds shall be plane surfaces with apermissible variation,in any 50-mm line on a surface,of0.03 mm for new molds and 0.05 mm for molds in use.Thedistance between opposit