ASTM_C_773_-_88_2016.pdf

Designation:C77388(Reapproved 2016)Standard Test Method forCompressive(Crushing)Strength of Fired WhitewareMaterials1This standard is issued under the fixed designation C773;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.Scope1.1 This test method covers two test procedures(A and B)for the determination of the compressive strength of firedwhiteware materials.1.2 Procedure A is generally applicable to whiteware prod-ucts of low-to moderately high-strength levels(up to 150 000psi or 1030 MPa).1.3 Procedure B is specifically devised for testing of high-strength ceramics(over 100 000 psi or 690 MPa).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.2.Referenced Documents2.1 ASTM Standards:2E4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical TestingE165 Practice for Liquid Penetrant Examination for GeneralIndustry3.Significance and Use3.1 Resistance to compression is the measure of the greateststrength of a ceramic material.Ideally,ceramics should bestressed this way in use.This test is a measure of the potentialload-bearing usefulness of a ceramic.PROCEDURE A4.Apparatus4.1 Testing MachineAny testing machine conforming toPractices E4 and to the requirements for speed of testingprescribed in Sections 5 and 12 of this test method,may beused.4.2 Spherical Bearing BlockIn vertical testing machines,the spherical bearing block shall be spring suspended from theupper head of the machine in such a manner that the upperplaten of the machine(lower face of the spherical bearingblock)remains in a central position(spherical surfaces in fullcontact)when not loaded.The spherical surfaces shall be welllubricated,and the center of curvature shall lie on the lowerface of the platen.The diagonal or diameter of the platen shallbe only slightly greater than the diagonal of the 112-in.(38.1-mm)square contact blocks to facilitate accurate center-ing of the specimens.4.3 Contact BlocksCold-rolled steel contact blocks shallbe used between the test specimen and the platens of themachine.These blocks shall be 112in.(38.1 mm)square by58to34in.(15.9 to 19.1 mm)thick,and the contact faces shall besurface ground until plane and parallel.The contact blocksshall be resurfaced,if necessary,after each strength test,andmay be reused only so long as the thickness remains over12in.(12.7 mm).If the contact block is cracked during testing,itshall be replaced.4.4 Cushion PadsCushion pads shall be used between thetest specimens and the contact blocks to aid in distributing theload.New cushion pads shall be used for each specimen.Suitable materials for cushion pads,selected in accordancewith the compressive strength range of the material beingtested,are shown in the following table:Compressive Strength Range,psi(MPa)Cushion Pad5000 to 50 000 incl(34.5 to 345)blotting paper,164in.(0.4 mm)thickOver 50 000 to 150 000 incl(345 to1030.0)mild steel,132in.(0.8 mm)thick(65HRB max)1This test method is under the jurisdiction ofASTM Committee C21 on CeramicWhitewares and Related Products and is the direct responsibility of SubcommitteeC21.03 on Methods for Whitewares and Environmental Concerns.Current edition approved July 1,2016.Published July 2016.Originally approvedin 1974 to replace C407 and C528.Last previous edition approved in 2011 asC773 88(2011).DOI:10.1520/C0773-88R16.2For 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 page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.Procedure5.1 Dye-check specimens in accordance with Test MethodE165 before testing.Discard any pieces exhibiting cracks orflaws visible to the unaided eye.5.2 Clean the test specimens with a suitable solvent aftergrinding and immerse in an ultrasonic bath filled with hotdetergent solution.Then rinse specimens in hot water,dry at110 6 2C(230 6 4F)for 2 h and cool to room temperaturein a desiccator.5.3 Carefully center the specimen in the machine betweenthe contact blocks.Place an appropriate guard around thespecimen to contain flying fragments at failure;eye protectionshould be used by the operator.5.4 Apply the load continuously and without impact shockuntil ultimate failure.The rate of loading to be used shalldepend on the compressive strength of the material beingtested,as shown in Table 1.6.Calculation6.1 Calculate the compressi