1、Designation: C 494/C 494M 05aStandard Specification forChemical Admixtures for Concrete1This standard is issued under the fixed designation C 494/C 494M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, the year of last revision. A
2、number in parentheses indicates the year of last reapproval.A superscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This specification covers materials for use as chemic
3、aladmixtures to be added to hydraulic-cement concrete mixturesin the field for the purpose or purposes indicated for the seventypes as follows:1.1.1 Type AWater-reducing admixtures,1.1.2 Type BRetarding admixtures,1.1.3 Type CAccelerating admixtures,1.1.4 Type DWater-reducing and retarding admixture
4、s,1.1.5 Type EWater-reducing and accelerating admixtures,1.1.6 Type FWater-reducing, high range admixtures, and1.1.7 Type GWater-reducing, high range, and retardingadmixtures.1.2 This specification stipulates tests of an admixture withsuitable concreting materials as described in 11.1-11.3 or withce
5、ment, pozzolan, aggregates, and an air-entraining admixtureproposed for specific work (11.4). Unless specified otherwiseby the purchaser, the tests shall be made using concretingmaterials as described in 11.1-11.3.NOTE 1It is recommended that, whenever practicable, tests be madeusing the cement, poz
6、zolan, aggregates, air-entraining admixture, and themixture proportions, batching sequence, and other physical conditionsproposed for the specific work (11.4) because the specific effects producedby chemical admixtures may vary with the properties and proportions ofthe other ingredients of the concr
7、ete. For instance, Types F and Gadmixtures may exhibit much higher water reduction in concrete mixtureshaving higher cement factors than that listed in 12.1.1.Mixtures having a high range water reduction generally display a higherrate of slump loss. When high-range admixtures are used to impartincre
8、ased workability (6 to 8-in. slump 150 to 200mm), the effect maybe of limited duration, reverting to the original slump in 30 to 60 mindepending on factors normally affecting rate of slump loss. The use ofchemical admixtures to produce high-slump (flowing) concrete is coveredby Specification C 1017.
9、NOTE 2The purchaser should ensure that the admixture supplied foruse in the work is equivalent in composition to the admixture subjected totest under this specification (see Section 6, Uniformity and Equivalence).NOTE 3Admixtures that contain relatively large amounts of chloridemay accelerate corros
10、ion of prestressing steel. Compliance with therequirements of this specification does not constitute assurance of accept-ability of the admixture for use in prestressed concrete.1.3 This specification provides for three levels of testing.1.3.1 Level 1During the initial approval stage, proof ofcompli
11、ance with the performance requirements defined inTable 1 demonstrates that the admixture meets the require-ments of this specification.Admixtures (except for Types B, C,and E) shall qualify for provisional compliance when any ofthe alternative compressive strength requirements in Table 1are met. If
12、subsequent test results at 6 months or one year failto meet the standard requirement of 100 % of referencestrength, the compliance of the admixture to this standard iswithdrawn and all users of the admixture shall be notifiedimmediately. Uniformity and equivalence tests of Section 6shall be carried
13、out to provide results against which latercomparisons can be made (See Note 4).NOTE 4Allowing for provisional compliance while retaining longerterm compressive strength requirements promotes more rapid qualificationof new materials, but also provides assurance that new admixturetechnologies will not
14、 exhibit unexpected longer term performance. Thealternative compressive strength requirements in Table 1 are based onstatistical analysis of 103 Specification C 494/C 494M evaluation tests.The alternative requirements correspond to a 99 % probability of passingsubsequent test age requirements.21.3.2
15、 Level 2Limited retesting is described in 5.2, 5.2.1and 5.2.2. Proof of compliance with the requirements of Table1 demonstrates continued conformity of the admixture with therequirements of the specification.1.3.3 Level 3For acceptance of a lot or for measuringuniformity within or between lots, when
16、 specified by thepurchaser, the uniformity and equivalence tests of Section 6shall be used.1.4 The values stated in either inch-pound or SI units shallbe regarded separately as standard. The values stated in each1This specification is under the jurisdiction of ASTM Committee C09 onConcrete Aggregate
17、s and is the direct responsibility of Subcommittee C09.23 onChemical Admixtures.Current edition approved Dec. 15, 2005. Published January 2006. Originallyapproved in 1962. Last previous edition approved in 2005 as C 494 05.2Supporting data have been filed at ASTM International Headquarters and maybe
18、 obtained by requesting Research Report RR: C09-1030.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.system may not be exact equivalents; therefore, each systemmust be used independently of the other, without combiningvalues in any w
19、ay.1.5 The text of this standard references notes and footnoteswhich provide explanatory material. These notes and footnotes(excluding those in tables and figures) shall not be consideredas requirements of the standard.1.6 The following precautionary caveat pertains only to thetest method sections,
20、Sections 11-18 of this Specification: Thisstandard does not purport to address all of the safety concerns,if any, associated with its use. It is the responsibility of the userof this standard to establish appropriate safety and healthpractices and determine the applicability of regulatory limita-tio
21、ns prior to use.2. Referenced Documents2.1 ASTM Standards:3C33 Specification for Concrete AggregatesC 39/C 39M Test Method for Compressive Strength of Cy-lindrical Concrete SpecimensC78 Test Method for Flexural Strength of Concrete (UsingSimple Beam with Third-Point Loading)C 136 Test Method for Sie
22、ve Analysis of Fine and CoarseAggregatesC 138/C 138M Test Method for Density (Unit Weight),Yield, and Air Content (Gravimetric) of ConcreteC 143/C 143M Test Method for Slump of Hydraulic-Cement ConcreteC 150 Specification for Portland CementC 157/C 157M Test Method for Length Change of Hard-ened Hyd
23、raulic-Cement Mortar and ConcreteC 183 Practice for Sampling and the Amount of Testing ofHydraulic CementC 192/C 192M Practice for Making and Curing ConcreteTest Specimens in the LaboratoryC 231 Test Method for Air Content of Freshly MixedConcrete by the Pressure MethodC 260 Specification forAir-Ent
24、rainingAdmixtures for Con-creteC 403/C 403M Test Method for Time of Setting of ConcreteMixtures by Penetration ResistanceC 666/C 666M Test Method for Resistance of Concrete toRapid Freezing and ThawingC 1017/C 1017M Specification for Chemical Admixturesfor Use in Producing Flowing ConcreteD75 Practi
25、ce for Sampling AggregatesD 1193 Specification for Reagent WaterE 100 Specification for ASTM HydrometersManual of Aggregate and Concrete Testing2.2 American Concrete Institute Standard:ACI 211.191 Standard Practice for Selecting Proportionsfor Normal, Heavyweight, and Mass Concrete43. Terminology3.1
26、 Definitions:3.1.1 accelerating admixturean admixture that acceler-ates the setting and early strength development of concrete.3.1.2 retarding admixturean admixture that retards thesetting of concrete.3.1.3 water-reducing admixturean admixture that reducesthe quantity of mixing water required to pro
27、duce concrete of agiven consistency.3.1.4 water-reducing admixture, high rangean admixturethat reduces the quantity of mixing water required to produceconcrete of a given consistency by 12 % or greater.3.1.5 water-reducing and accelerating admixtureanad-mixture that reduces the quantity of mixing wa
28、ter required toproduce concrete of a given consistency and accelerates thesetting and early strength development of concrete.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information,
29、refer to the standards Document Summary page onthe ASTM website.4Available from the American Concrete Institute, 38800 Country Club Drive,Farmington Hills, MI 48331.C 494/C 494M 05a23.1.6 water-reducing and retarding admixture an admix-ture that reduces the quantity of mixing water required toproduc
30、e concrete of a given consistency and retards the settingof concrete.3.1.7 water-reducing, high range, and retardingadmixturean admixture that reduces the quantity of mixingwater required to produce concrete of a given consistency by12 % or greater and retards the setting of concrete.4. Ordering Inf
31、ormation4.1 The purchaser shall specify the type of chemical admix-ture desired.5. General Requirements5.1 For initial compliance with this specification, test con-crete in which each type of admixture shown in 1.1 is usedshall conform to the respective requirements prescribed inTable 1.5.2 The purc
32、haser is allowed to require a limited retesting toconfirm current compliance of the admixture to specificationrequirements. The limited retesting will cover physical prop-erties and performance of the admixture.5.2.1 The physical properties retesting shall consist ofuniformity and equivalence tests
33、for infrared analysis, residueby oven drying and specific gravity.5.2.2 The performance property retesting shall consist ofwater content of fresh concrete, setting time and compressivestrength at 3, 7 and 28 days. Purchasers having specialrequirements are allowed to require additional tests currentl
34、y inthis standard.5.3 At the request of the purchaser, the manufacturer shallstate in writing that the admixture supplied for use in the workis identical in all essential respects, including concentration, tothe admixture tested under this specification.5.4 At the request of the purchaser, when the
35、admixture is tobe used in prestressed concrete, the manufacturer shall state inTABLE 1 Physical RequirementsAType A,WaterReducingType B,RetardingType C,Acceler-atingType D,WaterReducingandRetardingType E,WaterReducingandAcceleratingType F,WaterReducing,High RangeType G,WaterReducing,HighRangeand Ret
36、ardingWater content, max, % ofcontrol95 . . 95 95 88 88Time of setting, allowabledeviation from control, h:min:Initial: at least . 1:00 later 1:00 earlier 1:00 later 1:00 earlier . 1:00 laternot more than 1:00 earliernor 1:30later3:30 later 3:30 earlier 3:30 later 3:30 earlier 1:00 earliernor 1:30la
37、ter3:30 laterFinal: at least . . 1:00 earlier . 1:00 earlier . .not more than 1:00 earliernor 1:30later3:30 later . 3:30 later . 1:00 earliernor 1:30later3:30 laterCompressive strength, min, %of control:B1 day . . . . . 140 1253 days 110 90 125 110 125 125 1257 days 110 90 100 110 110 115 11528 days
38、 110(120)C90 100 110(120)C110 110(120)C110(120)C90 days (117)Cn/a n/a (117)Cn/a (117)C(117)C6 months 100(113)C90 90 100(113)C100 100(113)C100(113)C1 year 100 90 90 100 100 100 100Flexural strength, min,% control:B3 days 100 90 110 100 110 110 1107 days 100 90 100 100 100 100 10028 days 100 90 90 100
39、 100 100 100Length change, maxshrinkage (alternativerequirements):DPercent of control 135 135 135 135 135 135 135Increase over control 0.010 0.010 0.010 0.010 0.010 0.010 0.010Relative durabilityfactor, minE80 80 80 80 80 80 80AThe values in the table include allowance for normal variation in test r
40、esults. The object of the 90 % compressive strength requirement for a Type-B admixture is torequire a level of performance comparable to that of the reference concrete.BThe compressive and flexural strength of the concrete containing the admixture under test at any test age shall be not less than 90
41、 % of that attained at any previoustest age. The objective of this limit is to require that the compressive or flexural strength of the concrete containing the admixture under test shall not decrease with age.CAlternative requirement. If any of the measured relative strengths are greater than the re
42、quirement in parentheses, the admixture shall be considered provisionallyqualified until the 1-year strength test results are obtained.DAlternative requirements, see 17.1.4, % of control limit applies when length change of control is 0.030 % or greater; increase over control limit applies when lengt
43、hchange of control is less than 0.030 %.EThis requirement is applicable only when the admixture is to be used in air-entrained concrete which may be exposed to freezing and thawing while wet.C 494/C 494M 05a3writing the chloride content of the admixture and whether ornot chloride has been added duri
44、ng its manufacture.5.5 Tests for uniformity and equivalence, as indicated inSection 6, shall be made on the initial sample and the resultsretained for reference and comparison with the results of testsof samples taken from elsewhere within the lot or subsequentlots of admixture supplied for use in t
45、he work.6. Uniformity and Equivalence6.1 When specified by the purchaser, the uniformity of a lot,or the equivalence of different lots from the same source shallbe established by the use of the following requirements:6.1.1 Infrared AnalysisThe absorption spectra of the ini-tial sample and the test s
46、ample, obtained as specified in 18.1,shall be essentially similar.6.1.2 Residue by Oven Drying (Liquid Admixtures)Whendried as specified in 18.2, the oven-dried residues of the initialsample and of subsequent samples shall be within 6 12 % ofthe mid-point of the manufacturers stated range, but notex
47、ceeding the manufacturers stated limits (See Note 5).NOTE 5As an example, for an admixture produced with a residuerange from 27 to 35 %, the manufacturer would provide maximumacceptable limits of 27.3 to 34.7 %, representing 6 12 % of the mid-pointof the limits, where the mid-point is 31.0 %.6.1.3 R
48、esidue by Oven Drying (Nonliquid Admixtures)When dried as specified in 18.3, the oven-dried residues of theinitial sample and of the subsequent samples shall be within arange of variation not greater than 6 4 percentage points.6.1.4 Specific Gravity (Liquid Admixtures)When tested asspecified in 18.4
49、, the specific gravity of subsequent testsamples shall not differ from the specific gravity of the initialsample by more than 10 % of the difference between thespecific gravity of the initial sample and that of reagent waterat the same temperature. If 10 % of the difference between thespecific gravity of the initial sample and water is less than 0.01,use the value 0.01 as the maximum allowable difference.Reagent water conforming to Specification D 1193, Types IIIor IV, and prepared by distillation ion exchange, reverseosmosis, electrodialysis, or a c
