1、Designation: C563 16Standard Guide forApproximation of Optimum SO3in Hydraulic Cement UsingCompressive Strength1This standard is issued under the fixed designation C563; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of l
2、ast 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 guide describes the determination of approximateoptimum SO3for maximum compressive strength at 24 h,3 days, or 7 d
3、ays by measuring the change in strength producedin hydraulic cement mortar as a result of substituting calciumsulfate for a portion of the cement.1.2 This guide refers to the sulfur trioxide (SO3) content ofthe cement only. Slag cements and occasionally other hydrauliccements can contain sulfide or
4、other forms of sulfur. Thedetermination of SO3content by rapid methods may includethese other forms, and may therefore produce a significanterror. If a significant error occurs, analyze the cement for SO3content using the reference test method of Test Methods C114for sulfur trioxide.1.3 Values state
5、d as SI units are to be regarded as standard.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 regula
6、tory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C109/C109M Test Method for Compressive Strength ofHydraulic Cement Mortars (Using 2-in. or 50-mm CubeSpecimens)C114 Test Methods for Chemical Analysis of HydraulicCementC150 Specification for Portland CementC204 Test Methods fo
7、r Fineness of Hydraulic Cement byAir-Permeability ApparatusC305 Practice for Mechanical Mixing of Hydraulic CementPastes and Mortars of Plastic ConsistencyC471M Test Methods for ChemicalAnalysis of Gypsum andGypsum Products (Metric)C511 Specification for Mixing Rooms, Moist Cabinets,Moist Rooms, and
8、 Water Storage Tanks Used in theTesting of Hydraulic Cements and ConcretesC595 Specification for Blended Hydraulic CementsC1157 Performance Specification for Hydraulic CementC1437 Test Method for Flow of Hydraulic Cement Mortar3. Significance and Use3.1 The purpose of this guide is to estimate the S
9、O3contentfor a hydraulic cement that gives maximum compressivestrength in mortar made and cured at 23C. The value obtainedis one way to establish an appropriate level of sulfate in themanufacture of cements specified in Specifications C150, C595and C1157.3.2 The SO3content of a cement giving maximum
10、 compres-sive strength is different at different ages of mortar; typicallythis SO3content is higher at 3 days than the 24-h, and oftenhigher for 7 days than that for 3 days. A manufacturer canchoose the age of 24-h, 3 days or 7 days for specimens at whichto determine optimum SO3content.3.3 This guid
11、e indicates optimum SO3content for cement inmortar made and cured at a standard temperature of 23.0 62.0C (73.5 6 3.5F). The optimum SO3increases withincreasing temperature and may increase when water-reducingadmixtures are used.3.4 It should not be assumed that the optimum SO3esti-mated in this gui
12、de is the same SO3content for optimumperformance of a concrete prepared from the cement.3.5 The guide is applicable to cements specified in Specifi-cations C150, C595, and C1157.4. Apparatus4.1 Use the apparatus as specified in Test Method C109/C109M.5. Materials5.1 Calcium SulfateUse calcium sulfat
13、e for addition to thecement that is either a high-grade natural gypsum having an1This guide is under the jurisdiction of ASTM Committee C01 on Cement andis the direct responsibility of Subcommittee C01.28 on Sulfate ContentCurrent edition approved July 1, 2016. Published July 2016. Originally approv
14、edin 1965. Last previous edition approved in 2015 as C563 15. DOI: 10.1520/C0563-16.2For 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 p
15、age onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1SO3content of at least 46 %, or the calcium sulfate from thesource used for the intended plant production. Grind thecalcium sulfate to 100 % passing the 75-m (No.
16、200) sieve,and at least 800 m2/kg Blaine fineness (Test Method C204). Ifthe SO3content of the calcium sulfate is unknown, analyze itin accordance with Test Methods C471M.6. Procedure6.1 Sulfate Levels to TestTest at least five different sulfatelevels.6.1.1 SO3contents are to be at least 0.20 % diffe
17、rent unlessmore than five different SO3contents are being tested. Themaximum and minimum SO3content of the blended samplesmust differ by at least 2.0 % SO3content.NOTE 1More sulfate levels may be tested to help improve theprecision of the interpretation of the results. Extremely high and lowsulfate
18、levels can give results that deviate from the typical peak behaviorwhich may need to be treated as outliers when using a mathematical fittingprocedure.6.2 Determine mortar compressive strength at each sulfatelevel at the age of 24 614 h, 3 days 6 1 h, or 7 days 6 3hin accordance with Test Method C10
19、9/C109M except asfollows:6.2.1 When mixing in accordance with the “Procedure forMixing Mortars” section of Practice C305, add the calciumsulfate to the water, unless the calcium sulfate addition hasbeen previously ground and mixed with the cement; then startthe mixer and mix at slow speed (140 6 5 r
20、pm) for 15 s; thenstop the mixer and add the cement to the water; then start themixer and mix at slow speed (140 6 5 rpm) for 30 s.6.2.2 Use an amount of mixing water to produce a flow of110 6 5 using 25 drops of the table as determined in thesection on Procedures in Test Method C1437 for all types
21、ofcement.7. Interpretation of Results7.1 Approximate the SO3content which gives the maximumperformance by one of the following methods:7.1.1 Visual FitPlot the strength versus SO3content andinterpolate the sulfate level at the peak.7.1.2 Least Squares Parabolic Fit.7.1.2.1 Determine the equation of
22、a least squares fit accord-ing to follow equation:Strength 5 aSO3!21bSO31cwhere a, b, and c are fitting coefficients.NOTE 2Spreadsheet and graphing programs have the capability tocalculate the least squares parabolic fit.7.1.2.2 Approximate the optimum SO3by calculating vertexof the parabolic least
23、squares fit from the following equation:Optimum SO3approximation = 2 b2 a!where a and b are coefficients of the parabolic least squaresfit.7.1.3 Asymmetric FitIn cases where the strength versusSO3is skewed to the right or left of the peak a fit using anasymmetric distribution function may provide a
24、better fit thanparabolic fit.NOTE 3Mathematical and statistics software programs are useful indoing such fits.NOTE 4The sulfate level for the maximum performance may or maybe not the SO3content that one of the tests was conducted at.8. Retest8.1 If the approximate optimum sulfate level is greater or
25、lower than all the SO3contents tested, then test at additionalsulfate levels until at least one SO3content is greater than orless than approximate optimum SO3content. Repeat theinterpretation of results in Section 7 and report on that final setof results.9. Report9.1 Report the age of the test speci
26、mens.9.2 Report the method for interpretation of results and thetype of equation fit to, if using an asymmetric fit.9.3 Plot the strength versus SO3content, the approximateoptimum SO3content and any fit used.9.4 Report of the approximate optimum SO3value.10. Keywords10.1 blended hydraulic cement; ca
27、lcium sulfate; cement;compressive strength; gypsum; hydraulic cement; optimumsulfate content (of cement); portland cement; strength (ofcement); sulfate content (of cement)APPENDIX(Nonmandatory Information)X1. DISCUSSION OF THE TERM “OPTIMUM”X1.1 The scope statement notes that this test method deter-
28、mines the optimum SO3content in cements in mortar at aparticular temperature and age. Usually, but not always, theSO3content that produces the highest 24-h strength at 23Calso produces approximately the lowest expansion in water andthe lowest contraction in air at that temperature.C563 162X1.2 The “
29、optimum” determined by this test is approxi-mate. The “optimum” SO3content will vary with changes inmortar proportions; between cement paste, mortars and con-crete; will vary with the source of SO3; with the age of test;with the use of chemical admixtures; and with the use ofsupplementary cementitio
30、us materials. Thus, the term “opti-mum SO3” refers to an approximate value.X1.3 The age for determining the optimum is typicallychosen by the manufacturer based on experience with localconcrete materials.X1.4 For convenience, the method uses the compressivestrength of specimens at three different SO
31、3contents for thecement. If the strength results are plotted against SO3content,the three points are assumed to give a curve in the shape of aparabola, and the calculation used assumes this shape. If morepoints are used with smaller SO3content increments, the shapeof the curve is seen to be that of
32、a “sawtooth,” with adecreasing slope up to the apex at maximum strength, followedby a precipitous fall in strength immediately after the apex. Theapex represents the actual optimum SO3content, and istypically higher than that calculated using three points.Therefore, this affords a small “cushion” wh
33、en targeting thecalculated optimum SO3(determined using three points) dur-ing manufacture to allow for variation in the process.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
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