1、Designation: C1240 14Standard 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. Scope1.1 This specification covers silica fume for use in concreteand other systems containing hydraulic cement.1.2 In the cases of slurried or densif
3、ied silica fume, performthe tests on the raw silica fume from which these products havebeen made.1.3 The units stated in SI are to be regarded as the standard.1.4 The following safety hazards caveat pertains only to thetest methods portions, Sections 1019, of this specification-:This standard does n
4、ot 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 regulatorylimitations prior to use.Read the material safety data sheets format
5、erials 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 Documents2.1 ASTM Standards:2C109/C109M Test Method for Compressi
6、ve 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 Gravity of RefractoryMaterials by Water ImmersionC183 Practice for Sam
7、pling 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 Portland-Cement ConcreteC430 Test Method for Fineness of Hydrauli
8、c Cement by the45-m (No. 325) SieveC441 Test Method for Effectiveness of Pozzolans or GroundBlast-Furnace Slag in Preventing Excessive Expansion ofConcrete Due to the Alkali-Silica ReactionC494/C494M Specification for Chemical Admixtures forConcreteC604 Test Method for True Specific Gravity of Refra
9、ctoryMaterials 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 Use in the PhysicalTesting of Hydraulic CementsC1012 Test Method for
10、Length Change of Hydraulic-Cement Mortars Exposed to a Sulfate SolutionC1069 Test Method for Specific Surface Area of Alumina orQuartz by Nitrogen AdsorptionC1157 Performance Specification for Hydraulic CementC1437 Test Method for Flow of Hydraulic Cement Mortar3. Terminology3.1 Definitions:3.1.1 si
11、lica fume, nvery fine pozzolanic material, com-posed mostly of amorphous silica produced by electric arcfurnaces as a by-product of the production of elemental siliconor ferro-silicon alloys (also known as condensed silica fumeand microsilica).3.1.2 silica fume, densified, nsilica fume processed toi
12、ncrease bulk density to facilitate handling and shipping.3.1.3 silica fume, undensified, nsilica fume in its raw, asproduced or as collected, unprocessed form.3.1.4 Other terms in this specification are defined in Termi-nologies C125 and C219.4. Ordering Information4.1 The purchaser shall specify an
13、y optional chemical orphysical requirements.1This specification is under the jurisdiction of ASTM Committee C09 onConcrete and Concrete Aggregates and is the direct responsibility of SubcommitteeC09.24 on Supplementary Cementitious Materials.Current edition approved Feb. 15, 2014. Published March 20
14、14. Originallyapproved in 1993. Last previous edition approved in 2012 as C124012. DOI:10.1520/C1240-14.2For 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 standard
15、s Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15. Chemical Composition5.1 Silica fume shall conform to the requirements forchemical composition prescribed in Table 1.6. Physical Requirements
16、6.1 Silica fume shall conform to the physical requirementsprescribed in Table 2. Optional 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 acc
17、ordance with PracticeC183, modified as described in 7.3.NOTE 1Exercise caution in the 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 desig
18、n of the silica-fume collection system. Thedesign of silica-fume collection systems 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 modificat
19、ion of Practice C183 is neces-sary to render it applicable to silica fume.7.3.1 Replace 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.7.3.3 When compliance v
20、erification tests of silica fume arerequired to be made at a laboratory other 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 th
21、e test results will be availablewhen the decision to accept or reject the silica 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 of silica fume. Take a grab sample or acomposite sample for each
22、subsequent 100 Mg of silica fume,but not less than two samples shall be taken in any samplingprogram.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 t
23、he silica fume is flowing through theopenings, take samples 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 i
24、n 8.2, make all chemicaldeterminations and physical tests on composite samples repre-senting no more than 400 Mg each. Prepare each compositesample by combining portions from the samples representingeach 100 Mg, so that each 100 Mg is represented equally.8.2 Test for specific surface, density, and a
25、ccelerated poz-zolanic strength activity index using composite samples thatrepresent 3200 Mg or 3 months of production, whichever givesthe highest frequency. Prepare each composite sample bycombining portions from the samples representing each 400Mg or 1 month, whichever gives the highest frequency,
26、 so thateach 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 eachgroup representing the number of megagrams required by thetest or tests for which the composite sample is intended. F
27、romeach of the samples in a group, take equal portions, sufficientin amount to form a composite sample large enough to permitmaking the required physical or chemical determinations.TABLE 1 Chemical RequirementsSiO2,min,% 85.0Moisture content, max, % 3.0Loss on ignition, max, % 6.0TABLE 2 Physical Re
28、quirementsOversize: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
29、avoid retaining agglomerations of extremely fine material.BThe average shall consist of the ten preceding tests or all of the preceding testsif the number is less than ten.CAccelerated pozzolanic strength activity index is not to be considered a measureof the compressive strength of concrete contain
30、ing the silica fume. This is ameasure of the reactivity of a given silica fume with a given cement and may varywith 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-entraini
31、ng agent 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 exp
32、ansion,C(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
33、 an aggregate 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 t
34、est. The 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 1429.2 Prior to testing, mix grab samples and compositesamples thoroughly. A clean and dry laboratory concrete drummixer provides adequate mixing f
35、or this purpose. 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
36、 small sample 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 ar
37、ound for 5 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 To
38、tal Alkalies10.1 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 (ref
39、erto the section 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 Determine density using either Test Method C135 asmodified in 12.
40、1.1 or Test Method C604.12.1.1 Test Method C135 modified 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.12.2.3 Constant Temperature Bath, capable of being regu-lated within 60.5 C.12.3 Deionized Water.12.4 Procedure:12.4.1 D
41、etermine the density of the material as received,unless otherwise specified, as follows. If density determinationon an ignited sample is required, first ignite the sample asdescribed in the test for loss on ignition in the applicablesection given in Test Methods C114.12.4.2 Determine the mass (Wf),
42、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 flask to fill it one-half full, andshake it to ensure thorough wetting of the material. Fill to themark with water. Remove air bubb
43、les 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 in a constant temperature bath at 23 6 0.5 Cuntil the flask and its contents reach a constant temperature.Remove the flask from th
44、e 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 mass of the flask and its contents (Ws).12.4.3 Empty, clean, and determine the mass of the 500-mLvolumetric flask, used above, fille
45、d 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 volumetric flask, g,Wa= mass of 500-mL volumetric flask plus approximately30 g of silica fume, g,Ws= mass of 500-mL volumetric flask pl
46、us silica fume pluswater 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 determinations andthe test method used in determining the density.13. Oversize, Amount Retained When Wet-Sieved on a45-m (No. 325)
47、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 Surface14.1 Determine the specific surface by the BET, nitrogenadsorbtion method,
48、 in accordance with Test Method C1069.15. 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 300Silica fume, g 302030 Standard Ottawa sand, g 1170Water, mL, sufficient to give a f
49、low of 80 to 95 % YNeutralized Vinsol resin solution, mL, sufficient to produce anair content of 18 3 %ZWc5300111701301300 3P 30.01!300/3.1511170/2.65130/D!1300 3P 30.01!/1#(2)Then calculate:Air content, volume % 5 1001 2 Wa/Wc!#Wa5 W/400 (3)where:Wa= actual mass per unit of volume of mortar as determinedby Test Method C185, g/mL,C1240 143W = mass of the specified 400 mL of mortar (see TestMethod C185), g,Wc= theoretical mass per unit volume, calculated on anair-free basis and using the values for density andquantities of the materials in the mixt
