1、Designation: C 227 03Standard Test Method forPotential Alkali Reactivity of Cement-AggregateCombinations (Mortar-Bar Method)1This standard is issued under the fixed designation C 227; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、 the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript 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 test method covers
3、 the determination of the sus-ceptibility of cement-aggregate combinations to expansivereactions involving hydroxyl ions associated with the alkalies(sodium and potassium) by measurement of the increase (ordecrease) in length of mortar bars containing the combinationduring storage under prescribed c
4、onditions of test.1.2 Alkalies participating in the expansive reactions usuallyare derived from the cement; under some circumstances theymay be derived from other constituents of the concrete or fromexternal sources. Two types of alkali reactivity of aggregatesare recognized: (1) an alkali-silica re
5、action involving certainsiliceous rocks, minerals, and natural or artificial glasses and(2) an alkali-carbonate reaction involving dolomite in certaincalcitic dolomites and dolomitic limestones (see StandardC 294). The method is not recommended as a means to detectthe latter reaction because expansi
6、ons produced in the mortar-bar test by the alkali-carbonate reaction (see Test MethodC 586) are generally much less than those produced by thealkali-silica reaction for combinations having equally harmfuleffects in service.1.3 The values stated in SI units are to be regarded asstandard. The non-SI v
7、alues, shown in parentheses, are forinformational purposes only.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 appli
8、ca-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:C 33 Specification for Concrete Aggregates2C 109/C 109M Test Method for Compressive Strength ofHydraulic Cement Mortars (Using 2-in. or 50-mm CubeSpecimens)3C 289 Test Method for Potential Alkali-Silica Reacti
9、vity ofAggregates (Chemical Method)2C 294 Standard Descriptive Nomenclature for Constituentsof Concrete Aggregates2C 295 Guide for Petrographic Examination of Aggregatesfor Concrete2C 305 Practice for Mechanical Mixing of Hydraulic CementPastes and Mortars of Plastic Consistency3C 490 Practice for U
10、se of Apparatus for the Determinationof Length Change of Hardened Cement Paste, Mortar, andConcrete2,3C 511 Specification for Moist Cabinets, Moist Rooms, andWater Storage Tanks Used in Testing of Hydraulic Ce-ments and Concretes2,3C 586 Test Method for Potential Alkali Reactivity of Car-bonate Rock
11、s for Concrete Aggregates (Rock CylinderMethod)2C 856 Practice for Petrographic Examination of HardenedConcrete2C 1437 Test Method for Determining Flow of HydraulicCement Mortar3E 11 Specification for Wire Cloth and Sieves for TestingPurposes43. Significance and Use3.1 Data correlating the results o
12、f tests performed using thistest method with performance of cement-aggregate combina-tions in concrete in service, results of petrographic examinationof aggregates (Guide C 295), and results of tests for potentialreactivity of aggregates by chemical methods have beenpublished in Test Method C 289 an
13、d should be consulted inconnection with the use of results of tests performed using this1This test method is under the jurisdiction of ASTM Committee C09 onConcrete and Concrete Aggregates and is the direct responsibility of SubcommitteeC09.26 on Chemical Reactions of Materials.Current edition appro
14、ved June 10, 2003. Published September 2003. Originallyapproved in 1950. Last previous edition approved in 1997 as C 227 97a.2Annual Book of ASTM Standards, Vol 04.02.3Annual Book of ASTM Standards, Vol 04.01.4Annual Book of ASTM Standards, Vol 14.02.1Copyright ASTM International, 100 Barr Harbor Dr
15、ive, PO Box C700, West Conshohocken, PA 19428-2959, United States.test method as the basis for conclusions and recommendationsconcerning the use of cement-aggregate combinations in con-crete.3.2 The results of tests performed using this method furnishinformation on the likelihood that a cement-aggre
16、gate combi-nation is potentially capable of harmful alkali-silica reactivitywith consequent deleterious expansion of concrete. Criteria todetermine potential deleterious alkali-silica reactivity ofcement-aggregate combinations from the results of this testmethod have been given in the Appendix of Sp
17、ecification C 33.3.3 Insignificant expansion may result when potentiallydeleteriously reactive siliceous rocks are present in compara-tively high proportion even when a high-alkali cement is used.This may occur because the alkali-silica reaction products arecharacterized by an alkali to silica ratio
18、 that is so low as tominimize uptake of water and swelling, or because of alkalileaching from the bars (see section on containers). Dolomiticaggregates that are deleteriously affected by the alkali-carbonate reaction when employed as course aggregate inconcrete may not produce notable expansion in t
19、his testmethod. Also, significant expansion may occur rarely in the testfor reasons other than alkali-aggregate reaction, particularlythe presence of sulfates in the aggregate that produce a sulfateattack upon the cement paste, ferrous sulfides (pyrite, marca-site, or pyrrhotite) that oxidize and hy
20、drate with the release ofsulfate, and materials such as free lime (CaO) or free magnesia(MgO) in the cement or aggregate that progressively hydrateand carbonate.3.4 When expansions in excess of those given in theAppendix of Specification C 33 are shown in results of testsperformed using this test me
21、thod, it is strongly recommendedthat supplementary information be developed to confirm thatthe expansion is actually due to alkali reactivity. Sources ofsuch supplementary information include: (1) petrographicexamination of the aggregate to determine if known reactiveconstituents are present; (2) ex
22、amination of the specimens aftertests to identify the products of alkali reactivity; and (3) tests ofthe aggregate for potential reactivity by chemical methods(Test Method C 289).3.5 When it has been concluded from the results of testsperformed using this test method and supplementary informa-tion a
23、s outlined that a given cement-aggregate combinationshould be considered potentially deleteriously reactive, addi-tional studies may be appropriate to develop information on thepotential reactivity of other combinations containing the samecement with other aggregates, the same aggregate with otherce
24、ments, or the same cement-aggregate combination with amineral admixture.4. Apparatus4.1 The apparatus shall conform to Specification C 490,except as follows:4.2 SievesSquare hole, woven-wire cloth sieves, shallconform to Specification E 11.4.3 Mixer, Paddle, and Mixing Bowl Mixer, paddle, andmixing
25、bowl shall conform to the requirements of MethodC 305, except that the clearance between the lower end of thepaddle and the bottom of the bowl shall be 5 to 6 mm (0.20 to0.24 in.) .4.4 Tamper and TrowelThe tamper and trowel shall con-form to Test Method C 109/C 109M.4.5 ContainersCovered containers
26、for storing the testspecimens shall be constructed of material that is resistant tocorrosion under the test conditions. The wall thickness of thecontainer and cover shall be less than 6 mm (316 in.) to reducethe insulating effect and provide a rapid heat transfer for theinitial 14-day test period. T
27、he cover shall be constructed in amanner to maintain a tight seal between the cover and top ofthe container wall (Note 1). The container shall be arranged toprovide every surface of each specimen with approximately anequal exposure to an absorbent wicking material. The speci-mens shall not be in dir
28、ect contact with the wicking materialbut every surface shall be within 30 mm (114 in.) or less of thethe wicking. A typical arrangement of such a container isshown in Fig. 1 (Note 2). The inner sides and the center coreof the containers are to be lined with an absorbent material,such as blotting or
29、filter paper, to act as a wick and to ensurethat the atmosphere in the container is quickly saturated withwater vapor when it is sealed after the specimens are placedtherein (Note 2). The wicking liners will extend into the top ofthe water in the bottom of the container and above the tops ofthe spec
30、imens. Make provisions to support the bars in a verticalposition with the lower end of the bars approximately 25 mm(1 in.) above the surface of the water in the containers. Theweight of the specimens shall not be supported on the metalgage studs. A supporting rack shall be provided to ensure thatthe
31、 specimens do not touch the wicking material or each other.The supporting rack shall be constructed of brass wire or othermaterial that is resistant to corrosion under the test conditionsand shall not act as a vapor barrier but provide free movementof vapors within the container. Provisions shall be
32、 made toprevent water from splashing and dripping onto the specimens(Notes 3-5). If required to prevent the growth of mold on thewicking, add a suitable fungicide to the water in the container.The container size and internal arrangement of the specimensand wicking may be varied at the users discreti
33、on, providingexpansion data for all specimens can be shown to be equivalentto that developed with the container herein described.NOTE 1This seal may be achieved by a double wrap of vinyl tape 38mm (112 in.) or greater in width, overlaying the lid and container wallalong its full circumference.NOTE 2
34、A covered container that has been found acceptable for thispurpose is sold by the United States Plastic Corp., 1390 Neubrecht Rd.,Lima, OH 45801, as a PVC plating, photo, and chemical tank, stock No.10062, 6-in. diameter x 17 in. high, with cover.NOTE 3The shape and spacing of the center wicking mat
35、erial may bemaintained during the test by the use of rubber bands or hardware cloth.NOTE 4If concern exists for adequately preventing dripping orsplashing, the water should be tested for pH and alkali content.NOTE 5The container described in 4.5 and in Fig. 1 has been shownto produce large and repro
36、ducible expansions with cement-aggregatecombinations such as borosilicate glass: high-alkali cement combinationcalled for by ASTM C 441. However, recent work, at a few laboratories,suggests that the same factors that are responsible for the success with theC 441 mixtures, that is, high, constant, un
37、iform internal relative humidity,will, under certain testing regimes permitted by this test method, promoteleaching of alkali from the specimens and result in little or no expansionfrom some known deleteriously alkali-reactive aggregate: high-alkalicement combinations. Each laboratory should evaluat
38、e its containers witha known deleteriously alkali-reactive aggregate (not borosilicate glassC227032which releases alkali) and a high-alkali cement, to establish that theexpected level of expansion is obtained. If not, try removing the wickingto reduce the condensation and leaching. Minimizing the te
39、mperaturevariation within the storage room and the room in which the bars are readmay also reduce condensation on and leaching from the bars.5. Temperature and Humidity5.1 The temperature of the molding room and dry materialsshall be maintained at not less than 20C (68F) and not morethan 27.5C (81.5
40、F). The temperature of the mixing water, ofthe moist closet or moist room, and of the room in which themeasurements are made shall not vary from 23C (73.4F) bymore than 2.0C (3F).5.2 The relative humidity of the molding room shall be notless than 50 %. The moist closet or room shall conform toSpecif
41、ication C 511.5.3 The storage room in which the specimens in containersare stored shall be maintained at a temperature that shall notvary from 38.0C (100F) by more than 2.0C (3F).6. Selection and Preparation of Materials6.1 Selection of AggregateMaterials proposed for use asfine aggregate in concret
42、e shall be processed as described in6.2 with a minimum of crushing. Materials proposed for use ascoarse aggregate in concrete shall be processed by crushing toproduce as nearly as practical a graded product from which asample can be obtained. The sample shall have the grading asprescribed in 6.2 and
43、 be representative of the composition ofthe coarse aggregate as proposed for use.6.1.1 When a given quarried material is proposed for use,both as coarse and as fine aggregate, it will be tested only byselection of an appropriate sample crushed to the fine aggregatesizes, unless there is reason to ex
44、pect that the coarser sizefractions have a different composition than the finer sizes andthat these differences might significantly affect expansion dueto reaction with the alkalies in cement. In this case the coarsersize fractions should be tested in a manner similar to thatemployed in testing the
45、fine aggregate sizes.6.1.2 Coarse aggregate crushed to sand size may giveincreased expansion, owing to the increased surface exposedupon crushing. Therefore, if coarse aggregate tested by thismethod produces an excessive amount of expansion, thematerial shall not be classed as objectionably reactive
46、 withalkali unless tests of concrete specimens confirm the findingsof the tests of the mortar.6.2 Preparation of AggregateFine aggregate shall betested in a grading meeting the requirements of the specifica-tions for the project except that any material retained on the4.75-mm (No. 4) sieve shall be
47、removed. Fine aggregates beingtested for reasons other than to determine compliance withindividual specifications, and all coarse aggregates to whichthis method is applied shall be graded in accordance with therequirements prescribed in Table 1. Aggregates in whichsufficient quantities of the sizes
48、specified in Table 1 do not existshall be crushed until the required material has been produced.In the case of aggregates containing insufficient amounts of oneor more of the larger sizes listed in Table 1, and if no largermaterial is available for crushing, the first size in whichsufficient materia
49、l is available shall contain the cumulativepercentage of material down to that size as determined from theFIG. 1 Diagram of an Acceptable Assembled ContainerTABLE 1 Grading RequirementsSieve SizeMass %Passing Retained on4.75-mm (No. 4) 2.36-mm (No. 8) 102.36-mm (No. 8) 1.18-mm (No. 16) 251.18-mm (No. 16) 600-m (No. 30) 25600-m (No. 30) 300-m (No. 50) 25300-m (No. 50) 150-m (No. 100) 15C227033grading specified in Table 1. When such procedures arerequired, special note shall be made thereof in the test report.After the aggregate has been separated into th
copyright@ 2008-2019 麦多课文库（www.mydoc123.com）网站版权所有
备案/许可证编号：苏ICP备17064731号-1