1、Designation: C 1240 05Standard Specification forSilica Fume Used in Cementitious Mixtures1This standard is issued under the fixed designation C 1240; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A numb
2、er in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 de
3、nsified 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 p
4、ortions, 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 regulatoryl
5、imitations 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. Referenc
6、ed Documents2.1 ASTM Standards:2C 109/C 109M Test Method for Compressive Strength ofHydraulic Cement Mortars (Using 2-in. or 50-mm CubeSpecimens)C114 Test Methods for Chemical Analysis of HydraulicCementC 125 Terminology Relating to Concrete and ConcreteAggregatesC 183 Practice for Sampling and the
7、Amount of Testing ofHydraulic CementC 185 Test Method for Air Content of Hydraulic CementMortarC 219 Terminology Relating to Hydraulic CementC311 Test Methods for Sampling and Testing Fly Ash orNatural Pozzolans for Use in Portland-Cement ConcreteC 430 Test Method for Fineness of Hydraulic Cement by
8、the 45-m (No. 325) SieveC 441 Test Method for Effectiveness of Pozzolans orGround Blast-Furnace Slag in Preventing Excessive Ex-pansion of Concrete Due to the Alkali-Silica ReactionC 494 Specification for Chemical Admixtures for ConcreteC 670 Practice for Preparing Precision and Bias Statementsfor T
9、est Methods for Construction MaterialsC 1005 Specification for Reference Masses and Devices forDetermining Mass and Volume for Use in the PhysicalTesting of Hydraulic CementsC 1012 Test Method for Length Change of Hydraulic-Cement Mortars Exposed to a Sulfate SolutionC 1069 Test Method for Specific
10、Surface Area of Aluminaor Quartz by Nitrogen AdsorptionC 1157 Performance Specification for Hydraulic CementC 1437 Test Method for Flow of Hydraulic Cement Mortar3. Terminology3.1 Definitions:1This specification is under the jurisdiction of ASTM Committee C09 onConcrete and ConcreteAggregates and is
11、 the direct responsibility of SubcommitteeC09.24 on Supplementary and Cementitious Materials.Current edition approved July 1, 2005. Published August 2005. Originallyapproved in 1993. Last previous edition approved in 2004 as C 1240-04.2For referenced ASTM standards, visit the ASTM website, www.astm.
12、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.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box
13、 C700, West Conshohocken, PA 19428-2959, United States.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 andmicrosilic
14、a).3.1.2 Other terms in this specification are defined in Termi-nologies C 125 and C 219.4. Ordering Information4.1 The purchaser shall specify any optional chemical orphysical requirements.5. Chemical Composition5.1 Silica fume shall conform to the requirements forchemical composition prescribed in
15、 Table 1.6. Physical Requirements6.1 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,perfor
16、m the sampling and testing in accordance with PracticeC 183, modified as described in 7.3.NOTE 1Exercise caution in the interpretation of Practice C 183, sincethere is a difference between the continuous manufacture of hydrauliccement and the generation and collection of silica fume. To a great exte
17、nt,storage is dictated by the design of the silica-fume collection system. Thedesign of silica-fume collection systems may not have provided forsampling points and practices.7.2 Practice C 183, as modified, is not designed for manu-facturing quality control and is not required for manufacturerscerti
18、fication.7.3 The following modification of Practice C 183 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
19、at least 1 kg (2 lb).7.3.3 When compliance verification 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, ma
20、nufacturer,and testing laboratory so that the 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 (110 tons) of silica
21、fume. Take a grabsample or a composite sample for each subsequent 100 Mg(110 tons) of silica fume, but not less than two 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
22、completed. In sampling bulk storage atpoints of discharge, while the 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
23、, “General.”8. Frequency of Tests8.1 Except for the tests listed in 8.2, make all chemicaldeterminations and physical tests 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),
24、so that each 100 Mg isrepresented equally.8.2 Test for specific surface, density, and accelerated poz-zolanic strength activity index using composite samples thatrepresent 3200 Mg (3520 tons) or 3 months of production,whichever gives the highest frequency. Prepare each compositesample by combining p
25、ortions from the samples representingTABLE 1 Chemical RequirementsSiO2,min,% 85.0Moisture content, max, % 3.0Loss on ignition, max, % 6.0TABLE 2 Physical RequirementsOversize:Percent retained on 45-m (No. 325), max, %A10Percent retained on 45-m (No. 325), max variation fromaverage, percentage points
26、B5Accelerated pozzolanic strength activity index:CWith portland cement at 7 days, min percent of control 105Specific surface, min, m2/g 15AExercise care to avoid retaining agglomerations of extremely fine material.BThe average shall consist of the ten preceding tests or all of the precedingtests if
27、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 silica fume. Thisis a measure of the reactivity of a given silica fume with a given cement and mayvary with the source of both the silic
28、a fume and the cement.TABLE 3 Optional Physical RequirementsAUniformity requirements:When air-entraining concrete is specified, the quantity of air-entraining 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
29、preceding tests if less than ten, bymore than, %20Reactivity with cement alkalies:BReduction of mortar expansion at 14 days, min, % 80Sulfate resistance expansion,C(moderate resistance) 6 months, max, % 0.10(high resistance) 6 months, max, % 0.05(very high resistance) 1 year, max, % 0.05AWill be mad
30、e 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 aggregate that is regarded asdeleteriously reactive with alkalies in hydraulic cement. The test for reduction ofmortar expansion may be made
31、 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 test for mortar expansion should be performedby each of the high-alkali cements to be used in the work.COnly one limit shall be specifi
32、ed.C1240052each 400 Mg (440 tons) or 1 month, whichever gives thehighest frequency, so that each 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
33、megagrams required by thetest or tests for which the composite sample is intended. Fromeach 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.9.2 Prior to testing, mix grab samp
34、les and compositesamples thoroughly. A clean and dry laboratory concrete drummixer provides adequate mixing for 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 d
35、rum with an elastictiedown to keep the material in the drum. Limit the mixingaction to 5 6 1 min.9.2.1 When a 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 th
36、e sample in the bag, close the bagby tying the bag opening tightly, and mix the material byrolling the bag around 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
37、this testspecimen from at least six random subsamples.TEST METHODSCHEMICAL ANALYSIS10. Silicon Dioxide and Total Alkalies10.1 Reference MethodUse the reference method in TestMethods C114for cements with insoluble residue greater than1 %. Analysts performing sodium oxide and potassium oxidedeterminat
38、ions shall observe the precautions outlined in theapplicable section of Performance Specification C 1157 (referto 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 MethodsC31
39、1.TEST METHODSPHYSICAL TESTS12. Density12.1 Equipment:12.1.1 Two 500-mL Volumetric Flasks, Class A.12.1.2 Balance, with an accuracy of at least 0.01 g.12.1.3 Constant Temperature Bath, capable of being regu-lated within 60.5 C (1.0 F).12.2 Deionized Water.12.3 Procedure:12.3.1 Determine the density
40、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 C114.12.3.2 Determine the mass (Wf), of a 500-mL volumetri
41、cflask, 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 bubbles by shaking the fl
42、ask 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 the water bath; immedia
43、tely 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).12.3.3 Empty, clean, and determine the mass of the 500-mLvolumetric flask, used above, filled to the mark with wa
44、ter (Wt)stabilized at 23 6 0.5 C.12.4 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 plus silica fumeplus wa
45、ter to the mark, g,Wt= mass of 500-mL volumetric flask plus water to themark, g, andDw=(Wt Wf)/500-mL, Mg/m3.12.5 Report the average of two density determinations.13. Oversize, Amount Retained When Wet-Sieved on a45-m (No. 325) Sieve13.1 Use Test Method C 430. Calibrate the sieves in accor-dance wit
46、h Test Method C 430.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, in accordance with Test Method C 1069.315. Air Entrainment of Mortar1
47、5.1 Follow the applicable provisions of Test MethodsC311, except use the following test mixture and equation forWc:Test MixturePortland cement, g 3003Manufacturers and examples of nitrogen adsorbtion instrumentation includeHoriba Instruments, Inc., Irvine, CA, 5A-9600; Micromeritics Instrument Corpo
48、ra-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 proce
49、dures.C1240053Silica fume, g 302030 Standard Ottawa sand, g 1170Water, mL, sufficient to give a flow of 80 to 95 % YNeutralized Vinsol resin solution, mL, sufficient to produce anair content of 18 6 3%ZWc5300 1 1170 1 30 1 300 3 P 3 0.01!300/3.15 1 1170/2.65 1 30/D! 1 300 3 P 3 0.01!/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 deter-mined by Test Method C 185, g/mL,W = mass of the specified 400 mL of mortar (see TestMethod C 185), g,Wc= theoretical mass per unit volume, calcu
