1、Designation: C1240 10Standard Specification forSilica Fume Used in Cementitious Mixtures1This standard is issued under the fixed designation C1240; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number
2、 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 specification covers silica fume for use in concreteand other systems containing hydraulic cement.1.2 In the cases of slurried or densi
3、fied silica fume, performthe tests on the raw silica fume from which these products havebeen made.1.3 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.4 The following safety hazards caveat pertains only to thetest methods port
4、ions, Sections 10-19, of this specification:This standard does not purport to address all of the safetyconcerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety andhealth practices and determine the applicability of regulatorylimi
5、tations prior to use. Read the material safety data sheets formaterials used.1.5 The text of this standard references notes and footnotesthat provide explanatory information. These notes and foot-notes (excluding those in tables) shall not be considered asrequirements of this standard.2. Referenced
6、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 HydraulicCementC125 Terminology Relating to Concrete and Concrete Ag-gregatesC135 Test Method for True Specific Gravi
7、ty of RefractoryMaterials by Water ImmersionC183 Practice for Sampling and the Amount of Testing ofHydraulic CementC185 Test Method for Air Content of Hydraulic CementMortarC219 Terminology Relating to Hydraulic CementC311 Test Methods for Sampling and Testing Fly Ash orNatural Pozzolans for Use in
8、Portland-Cement ConcreteC430 Test Method for Fineness of Hydraulic Cement by the45-m (No. 325) SieveC441 Test Method for Effectiveness of Pozzolans orGround Blast-Furnace Slag in Preventing Excessive Ex-pansion of Concrete Due to the Alkali-Silica ReactionC494/C494M Specification for Chemical Admixt
9、ures forConcreteC604 Test Method for True Specific Gravity of RefractoryMaterials by Gas-Comparison PycnometerC670 Practice for Preparing Precision and Bias Statementsfor Test Methods for Construction MaterialsC1005 Specification for Reference Masses and Devices forDetermining Mass and Volume for Us
10、e in the PhysicalTesting of Hydraulic CementsC1012 Test Method for Length Change of Hydraulic-Cement Mortars Exposed to a Sulfate SolutionC1069 Test Method for Specific SurfaceArea ofAlumina orQuartz by Nitrogen AdsorptionC1157 Performance Specification for Hydraulic CementC1437 Test Method for Flow
11、 of Hydraulic Cement Mortar3. Terminology3.1 Definitions:3.1.1 silica fumevery fine pozzolanic material, composedmostly of amorphous silica produced by electric arc furnaces asa by-product of the production of elemental silicon or ferro-silicon alloys (also known as condensed silica fume andmicrosil
12、ica).1This specification is under the jurisdiction of ASTM Committee C09 onConcrete and ConcreteAggregates and is the direct responsibility of SubcommitteeC09.24 on Supplementary Cementitious Materials.Current edition approved Oct. 15, 2010. Published November 2010. Originallyapproved in 1993. Last
13、previous edition approved in 2005 as C1240-05. DOI:10.1520/C1240-10.2For 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 w
14、ebsite.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.2 Other terms in this specification are defined in Termi-nologies C125 and C219.4. Ordering Information4.1 T
15、he purchaser shall specify any optional chemical orphysical requirements.5. Chemical Composition5.1 Silica fume shall conform to the requirements forchemical composition prescribed in Table 1.6. Physical Requirements6.1 Silica fume shall conform to the physical requirementsprescribed in Table 2. Opt
16、ional physical requirements are givenin Table 3.7. Sampling7.1 When the purchaser desires that the silica fume besampled and tested to verify compliance with this specification,perform the sampling and testing in accordance with PracticeC183, modified as described in 7.3.NOTE 1Exercise caution in th
17、e interpretation of Practice C183, sincethere is a difference between the continuous manufacture of hydrauliccement and the generation and collection of silica fume. To a great extent,storage is dictated by the design of the silica-fume collection system. Thedesign of silica-fume collection systems
18、may not have provided forsampling points and practices.7.2 Practice C183, as modified, is not designed for manu-facturing quality control and is not required for manufacturerscertification.7.3 The following modification of Practice C183 is neces-sary to render it applicable to silica fume.7.3.1 Repl
19、ace the words “hydraulic cement” and “cement”with the words “silica fume” every time that they appear in thetext.7.3.2 All samples, whether grab or composite, shall have amass of at least 1 kg (2 lb).7.3.3 When compliance verification tests of silica fume arerequired to be made at a laboratory other
20、 than that of thesilica-fume manufacturer or marketer, coordinate the silica-fume sampling schedule, sample transportation time, andsample testing schedule among the purchaser, manufacturer,and testing laboratory so that the test results will be availablewhen the decision to accept or reject the sil
21、ica fume must bemade.7.3.4 The section entitled “Sampling” is modified as fol-lows:7.3.4.1 Take two grab samples or two composite samplesfor the first 100 Mg (110 tons) of silica fume. Take a grabsample or a composite sample for each subsequent 100 Mg(110 tons) of silica fume, but not less than two
22、samples shall betaken in any sampling program.7.3.4.2 From Bulk Storage at Points of DischargeWithdraw silica fume from the discharge openings in a steadystream until sampling is completed. In sampling bulk storage atpoints of discharge, while the silica fume is flowing through theopenings, take sam
23、ples at such intervals so that, at a minimum,the sampling requirements of 7.3.4.1 are met.7.3.5 The section entitled “Amount of Testing” is modifiedby deleting the first paragraph, “General.”8. Frequency of Tests8.1 Except for the tests listed in 8.2, make all chemicaldeterminations and physical tes
24、ts on composite samples repre-senting no more than 400 Mg (440 tons) each. Prepare eachcomposite sample by combining portions from the samplesrepresenting each 100 Mg (110 tons), so that each 100 Mg isrepresented equally.8.2 Test for specific surface, density, and accelerated poz-zolanic strength ac
25、tivity index using composite samples thatrepresent 3200 Mg (3520 tons) or 3 months of production,whichever gives the highest frequency. Prepare each compositesample by combining portions from the samples representingeach 400 Mg (440 tons) or 1 month, whichever gives thehighest frequency, so that eac
26、h sample is represented equally.9. Preparation of Sample9.1 Prepare composite samples for tests, as required inSection 8, by arranging all test samples in groups, with eachTABLE 1 Chemical RequirementsSiO2,min,% 85.0Moisture content, max, % 3.0Loss on ignition, max, % 6.0TABLE 2 Physical Requirement
27、sOversize:Percent retained on 45-m (No. 325), max, %A10Percent retained on 45-m (No. 325), max variation fromaverage, percentage pointsB5Accelerated pozzolanic strength activity index:CWith portland cement at 7 days, min percent of control 105Specific surface, min, m2/g 15AExercise care to avoid ret
28、aining agglomerations of extremely fine material.BThe average shall consist of the ten preceding tests or all of the precedingtests if the number is less than ten.CAccelerated pozzolanic strength activity index is not to be considered ameasure of the compressive strength of concrete containing the s
29、ilica fume. Thisis a measure of the reactivity of a given silica fume with a given cement and mayvary with the source of both the silica fume and the cement.TABLE 3 Optional Physical RequirementsAUniformity requirements:When air-entraining concrete is specified, the quantity of air-entraining agent
30、required to produce air content of 18.0 vol %of mortar shall not vary from the average established by the tenpreceding tests or by all preceding tests if less than ten, bymore than, %20Reactivity with cement alkalies:BReduction of mortar expansion at 14 days, min, % 80Sulfate resistance expansion,C(
31、moderate resistance) 6 months, max, % 0.10(high resistance) 6 months, max, % 0.05(very high resistance) 1 year, max, % 0.05AWill be made only at the request of the purchaser.BThe indicated tests for reactivity with cement alkalies shall not be requestedunless the material is to be used with an aggre
32、gate that is regarded asdeleteriously reactive with alkalies in hydraulic cement. The test for reduction ofmortar expansion may be made using any high-alkali cement in accordance withTest Methods C311, if the cement to be used in the work is not known or is notavailable at the time of the test. The
33、test for mortar expansion should be performedby each of the high-alkali cements to be used in the work.COnly one limit shall be specified.C1240 102group representing the number of megagrams required by thetest or tests for which the composite sample is intended. Fromeach of the samples in a group, t
34、ake equal portions, sufficientin amount to form a composite sample large enough to permitmaking the required physical or chemical determinations.9.2 Prior to testing, mix grab samples and compositesamples thoroughly. A clean and dry laboratory concrete drummixer provides adequate mixing for this pur
35、pose. Take care tolimit the volume of silica fume in the drum mixer to the rangeof 10 to 50 % of the drums total capacity. If necessary, securea sheet of polyethylene film on the drum with an elastictiedown to keep the material in the drum. Limit the mixingaction to 5 6 1 min.9.2.1 When a small samp
36、le size precludes the use of aconcrete mixer, use a heavy plastic bag, of a capacity at leastfive times larger than the sample volume, to mix the samplethoroughly. After placing the sample in the bag, close the bagby tying the bag opening tightly, and mix the material byrolling the bag around for 5
37、6 1 min.9.3 Take material for specific tests from a thoroughly mixedsample by using a sampling device (sampling tube, scoop, etc.)of appropriate size to make a test specimen. Make this testspecimen from at least six random subsamples.TEST METHODSCHEMICAL ANALYSIS10. Silicon Dioxide and Total Alkalie
38、s10.1 Reference MethodUse the reference method in TestMethods C114 for cements with insoluble residue greater than1 %. Analysts performing sodium oxide and potassium oxidedeterminations shall observe the precautions outlined in theapplicable section of Performance Specification C1157 (referto the se
39、ction on Test Methods). Most pozzolans dissolvecompletely in lithium borate fluxes.11. Moisture Content and Loss on Ignition11.1 Follow the applicable provisions of Test MethodsC311.TEST METHODSPHYSICAL TESTS12. Density12.1 Test Method C135 has been adapted for determiningthe density of silica fume.
40、 Test Method C604, which utilizes ahelium pycnometer is quick, precise, and is an alternativemethod that is acceptable for density determinatinos.12.1.1 Test Method C135 adapted as follows:12.2 Equipment:12.2.1 Two 500-mL Volumetric Flasks, Class A.12.2.2 Balance, with an accuracy of at least 0.01 g
41、.12.2.3 Constant Temperature Bath, capable of being regu-lated within 60.5 C (1.0 F).12.3 Deionized Water.12.4 Procedure:12.4.1 Determine the density of the material as received,unless otherwise specified, as follows. If density determinationon an ignited sample is required, first ignite the sample
42、asdescribed in the test for loss on ignition in the applicablesection given in Test Methods C114.12.4.2 Determine the mass (Wf), of a 500-mL volumetricflask, to an accuracy of 0.01 g. Add 30 g of silica fume.Determine the mass of the flask and the contents (Wa)tothenearest 0.01 g.Add water to the fl
43、ask to fill it one-half full, andshake it to ensure thorough wetting of the material. Fill to themark with water. Remove air bubbles by shaking the flask at15-min intervals until the liquid is free of air or by applying avacuum to the flask. After all of the air bubbles are removed,place the flask i
44、n a constant temperature bath at 23 6 0.5 Cuntil the flask and its contents reach a constant temperature.Remove the flask from the water bath; immediately add orremove water, at the same temperature, to the flask to get themeniscus on the mark. Wipe dry the exterior of the flask anddetermine the mas
45、s of the flask and its contents (Ws).12.4.3 Empty, clean, and determine the mass of the 500-mLvolumetric flask, used above, filled to the mark with water (Wt)stabilized at 23 6 0.5 C.12.5 Calculation:Dsf5Wa2 Wf!500 mL 2 Ws2 Wa!/Dw#(1)where:Dsf= density of silica fume, Mg/m3,Wf= mass of 500-mL volume
46、tric flask, g,Wa= mass of 500-mL volumetric flask plus approximately30 g of silica fume, g,Ws= mass of 500-mL volumetric flask plus silica fumeplus water to the mark, g,Wt= mass of 500-mL volumetric flask plus water to themark, g, andDw=(Wt Wf)/500-mL, Mg/m3.12.6 Report the average of two density de
47、terminations.13. Oversize, Amount Retained When Wet-Sieved on a45-m (No. 325) Sieve13.1 Use Test Method C430. Calibrate the sieves in accor-dance with Test Method C430.NOTE 2Oversize is used to determine the amount of contaminatingmaterial retained on the 45-m sieve. See Appendix X2.14. Specific Sur
48、face14.1 Determine the specific surface by the BET, nitrogenadsorbtion method, in accordance with Test Method C1069.315. Air Entrainment of Mortar15.1 Follow the applicable provisions of Test MethodsC311, except use the following test mixture and equation forWc:Test MixturePortland cement, g 300Sili
49、ca fume, g 302030 Standard Ottawa sand, g 1170Water, mL, sufficient to give a flow of 80 to 95 % Y3Manufacturers and examples of nitrogen adsorbtion instrumentation includeHoriba Instruments, Inc., Irvine, CA, 5A-9600; Micromeritics Instrument Corpora-tion, Norcross Georgia, FlowSorb-II 2300; Quantachrome Corporation, BoyntonBeach, FL, Quantasorb Jr.; and JUWE Laborgerate Service GmbH, Korschenbroich,Germany, Stroehlein AREAmeter II. NIST SRMt 2696, Silica Fume, is availablefor use in comparison and evaluation of laboratory equipment and procedures.C1240 103
