ASTM_C_191-2013.pdf

C191-13edge of the trowel.Repeat the cutting and smoothing steps butfuture qualification and standardization.at 90 from the previous cut.Repeat the steps as required to18.3 Tests-Using the method to be qualified and includingproduce a surface level with the top of the mold.Usually thethe standardization formula described in the section onpaste is level within two cycles,but occasionally three will bestandardization,make single determinations of the times ofrequired.Avoid excessive strokes and compaction.Since theinitial and final setting on each of the three cements.On theautomatic Vicat device references to the top edge of the mold,same day,conduct companion time of setting determinationsit is imperative that the top surface of the paste be uniform andaccording to Method A.Make single determinations of thelevel with the top of the mold.normal consistency on each cement,and use that amount of17.2 Time of Setting Determinations-Follow the manufac-water for all replicate batches.Complete three rounds of teststurers instructions and complete the required instrumenton different days,repeating all the steps of the methods.calibration and zero procedures.Set the instrument to measureConduct the qualification tests on specimens prepared sepa-no less frequently than every 10 min(see Note 3).Position therately from the standardization testing.molded specimen in the automatic Vicat apparatus and initiate18.4 Calculations-Calculate the three-round averages forthe measurements(see Note 4).initial and final time of setting for each cement and method.ANorE 3-Automatic devices are usually capable of measurement moremethod complies with the initial time of setting qualificationfrequently than once every 10 min and more frequent measurementrequirements if the difference between the initial time of settingminimizes interpolation.NorE 4-The initial time of setting according to Method A is deter-average values for Method A and the corresponding averagemined as the elapsed time required to achieve a penetration of 25 mm andvalues of Method B is not greater than 25 min for any sample,the final time of setting as the total time elapsed until the needle does notand the range for any three replicate tests by Method B doesleave a complete circular impression in the paste surface.The end pointsnot exceed 30 min.Likewise,a method complies with the finalestablished by a qualified automatic Vicat test method may deviatetime of setting qualification requirements if the differencesignificantly from end points specified in Method A.and require standard-ization to correct bias.between the final time of setting average values for Method A17.3 Determine the range of applicability of the methodand corresponding average values for Method B is not greaterthan 45 min for any sample,and the range for any threefrom the range of the average time of setting of the cementsreplicate tests by Method B does not exceed 30 min.Exampleused for qualification and standardization,and limit that rangeto 30 min greater than the maximum,and 30 min less than thequalification data are given in Appendix X1.minimum.18.5 Standardization-When standardization is required in17.4 Performance Requirement(Qualification)for Auto-order to achieve agreement between Method A and Method B.it can be applied to either the initial time of setting,final timematic Vicat Instrument:17.4.1 When time of setting results from the automatic Vicatof setting,or both.A standardization formula shall be based onapparatus are to be used for acceptance or rejection of cement,a comparison of test results obtained using Method A and thethe method used shall comply with the qualification require-chosen method using the automatic instrument(Method B).ments covered in Annex A2Results of tests from at least five different hydraulic cementsshall be required for standardization.The cements shall have a18.Performance Requirement(Qualification)forminimum range of 60 min initial time of setting,and aAutomatic Vicat Instrumentminimum range of 90 min final time of setting when tested inaccordance with Method A.If desired,the three cements used18.1 Scope-When time of setting results from the auto-for instrument qualification may be used,but make newmatic Vicat apparatus are to be used for acceptance or rejectiondeterminations.Use the same method as used for instrumentof cement,the method used shall comply with the qualificationqualification,including all the same steps.Valid standardiza-requirements of this section.A method is considered to consisttion formulas shall be mathematically derived and applied toof the specific instrument and the molding procedure meetingall samples(see Note 6).the requirements of this standard,and used in a consistentmanner by a given laboratory.NorE 6-Generally,the automatic instruments are computer operatedand easily adapted to standardization calculations.18.2 Hydraulic Cement Samples Required-Select threecements that comply with requirements of Specifications C150.19.Requalification of a MethodC595,or C1157,and that when tested in accordance withMethod A,shall include the following:19.1 Requalify the method at least once per year and when18.2.1 One cement that has an initial time of setting of lessany of the following conditions occur:than 110 min.19.1.1 The instrument has been significantly modified.18.2.2 One cement with an initial time of setting of greater19.1.2 The instrument has been substantially repaired.than 150 min.19.1.3 Substantial evidence indicates that the method is not18.2.3 One cement with a final time of setting of less thanproviding data meeting the performance requirements.180 min,and18.2.4 One cement with a final time of setting of greater19.1.4 The average of a Cement and Concrete ReferenceLaboratory(CCRL)sample differs from the value obtained bythan 210 min(see Note 5).the method by more than 45 min for either the initial or finalNorE 5-Laboratories are advised to reserve sufficient cement fortime of setting.wrh ASTMmtled without Fcense from IHSNot for ResaleC191-1320.Precision and Bias21.Keywords20.1 Precision-Since Method B represents procedures spe-21.1 automatic vicat;hydraulic-cement paste;time of set-cific to a laboratory that have been qualified in comparison toting;vicat;vicat needleMethod A,no statement on precision is being made.20.2 Bias-Since there are no accepted reference materialssuitable for determining the bias for the procedure in this testmethod,no statement on bias is presented.ANNEXES(Mandatory Information)A1.VICAT APPARATUSA1.1 The Vicat apparatus shall consist of a frame,A,Fig.A1.1,bearing a movable rod,B,with a mass as specified by themethod referencing this apparatus,one end,C,the plunger end,with a diameter as specified by the method referencing thisapparatus,and the other end having a mass or a removable steelneedle,D,as specified by the method referencing this appara-tus.The rod.B.is reversible.and can be held in any desiredposition by a setscrew,E,and has an adjustable indicator,F,which moves over a scale graduated in millimetres andattached to the frame,A.The gradations on the graduated scale,when compared to a scale accurate to within 0.1 mm at allpoints,shall not show a variance from the reference scalegreater than 0.25 mm.Entire 50mm.langthgraduatad inmillimetres20FIG.A1.1 Vicat Apparatuse wth ASTMNot for Resale