1、221R-1This guide presents information on selection and use of normal weight andheavyweight aggregates in concrete. The selection and use of aggregates inconcrete should be based on technical criteria as well as economic consid-erations and knowledge of types of aggregates generally available in thea
2、rea of construction. The properties of aggregates and their processing andhandling influence the properties of both plastic and hardened concrete.The effectiveness of processing, stockpiling, and aggregate quality controlprocedures will have an effect on batch-to-batch and day-to-day variationin the
3、 properties of concrete. Aggregates that do not comply with the speci-fication requirements may be suitable for use if the properties of the con-crete using these aggregates are acceptable. This is discussed under thetopic of marginal aggregates (Chapter 6). Materials that can be recycled orproduced
4、 from waste products are potential sources of concrete aggre-gates; however, special evaluation may be necessary.Keywords: aggregate grading; aggregate shape and texture; air entrain-ment; blast-furnace slag; bleeding (concrete); coarse aggregates; concretes;crushed stone; degradation resistance; de
5、nsity (mass/volume); fine aggre-gates; mix proportioning; modulus of elasticity; pumped concrete; qualitycontrol; recycling; shrinkage; strength; tests; workability.CONTENTSChapter 1Introduction, p. 221R-2Chapter 2Properties of hardened concrete influenced by aggregate properties, p. 221R-22.1Durabi
6、lity2.2Strength2.3Shrinkage2.4Thermal properties2.5Unit weight2.6Modulus of elasticity2.7Surface frictional properties2.8EconomyChapter 3Properties of freshly mixed concrete influenced by aggregate properties, p. 221R-123.1General3.2Mixture proportions3.3Slump and workability3.4Pumpability3.5Bleedin
7、g3.6Finishing characteristics of unformed concrete3.7Air content3.8Other propertiesChapter 4Effects of processing and handling of aggregates on properties of freshly mixed and hardened concrete, p. 221R-154.1General4.2Basic processing 4.3Beneficiation4.4Control of particle shape4.5Handling of aggreg
8、ates4.6Environmental concernsACI 221R-96(Reapproved 2001)Guide for Use of Normal Weight and Heavyweight Aggregates in ConcreteReported by ACI Committee 221Joseph F. LamondChairmanWilliam P. Chamberlin Kenneth MacKenzie James S. PierceHormoz Famili Gary R. Mass Raymond PisaneschiStephen W. Forster Ri
9、chard C. Meininger John M. Scanlon, Jr.Truman R. Jones, Jr. Frank P. Nichols, Jr. Charles F. ScholerDah-Yinn Lee Everett W. Osgood David C. StarkDonald W. Lewis Michael A. Ozol Robert E. TobinRobert F. Adams, Consulting MemberACI Committee Reports, Guides, Standard Practices, and Commentariesare int
10、ended for guidance in planning, designing, executing, and inspect-ing construction. This document is intended for the use of individualswho are competent to evaluate the significance and limitations of itscontent and recommendations and who will accept responsibility forthe application of the materi
11、al it contains. The American Concrete In-stitute disclaims any and all responsibility for the stated principles. TheInstitute shall not be liable for any loss or damage arising therefrom.Reference to this document shall not be made in contract documents.If items found in this document are desired by
12、 the Architect/Engineer tobe a part of the contract documents, they shall be restated in mandatorylanguage for incorporation by the Architect/Engineer.ACI 221R-96 supersedes ACI 221R-89 and became effective May 5, 1996.Copyright 1997, American Concrete Institute.All rights reserved including rights
13、of reproduction and use in any form or by anymeans, including the making of copies by any photo process, or by electronic or mechan-ical device, printed, written, or oral, or recording for sound or visual reproduction or foruse in any knowledge or retrieval system or device, unless permission in wri
14、ting isobtained from the copyright proprietors.221R-2 ACI COMMITTEE REPORTChapter 5Quality assurance, p. 221R-205.1General5.2Routine visual inspection5.3Routine control testing5.4Acceptance testing5.5Record keeping and reportsChapter 6Marginal and recycled aggregates, p. 221R-236.1Marginal aggregate
15、s6.2Use of marginal aggregates6.3Beneficiation of marginal aggregates6.4Economy of marginal aggregates6.5Recycled aggregates and aggregates from wasteproductsChapter 7Heavyweight aggregates, p. 221R-257.1Introduction7.2Heavyweight aggregate materials7.3Properties and specifications for heavyweight a
16、ggre-gates7.4Proportioning heavyweight concrete7.5Aggregates for use in radiation-shielding concrete7.6Heavyweight aggregate supply, storage, and batch-ingChapter 8References, p. 221R-268.1Recommended references 8.2Cited referencesCHAPTER 1INTRODUCTIONAggregates, the major constituent of concrete, i
17、nfluence theproperties and performance of both freshly mixed and hard-ened concrete. In addition to serving as an inexpensive filler,they impart certain positive benefits that are described in thisguide. When they perform below expectation, unsatisfactoryconcrete may result. Their important role is
18、frequently over-looked because of their relatively low cost as compared to thatof cementitious materials.This guide is to assist the designer in specifying aggregateproperties. It also may assist the aggregate producer and userin evaluating the influence of aggregate properties on con-crete, includi
19、ng identifying aspects of processing and han-dling that have a bearing on concrete quality and uniformity.The report is limited primarily to natural aggregates, crushedstone, air-cooled blast-furnace slag, and heavyweight aggre-gate. It does not include lightweight aggregates. The types ofnormal wei
20、ght and heavyweight aggregates listed are thosecovered by ASTM C 33, ASTM C 63, and other standardizedspecifications. In most cases, fine and coarse aggregatemeeting ASTM C 33 will be regarded as adequate to insuresatisfactory material. Experience and test results of thosematerials are the basis for
21、 discussion of effects on concreteproperties in this guide. Other types of slag, waste materials,and marginal or recycled materials may require special in-vestigations for use as concrete aggregate. Definitions andclassifications of concrete aggregates are given in ACI116R.This guide is divided into
22、 six major parts: (1) propertiesof hardened concrete influenced by aggregate properties,(2) properties of freshly mixed concrete influenced by ag-gregate properties, (3) aspects of processing and handlingwhich have a bearing on concrete quality and uniformity,(4) quality control, (5) marginal and re
23、cycled aggregates,and (6) heavyweight aggregate.While a designer or user does not normally specify themethods and equipment to be used in aggregate processingor beneficiation, processing may influence properties im-portant to performance. Therefore, Chapter 4 is includednot only as a guide for aggre
24、gate producers but for the ben-efit of anyone who must frequently handle aggregates.Aggregate selection should be based on technical criteriaand economic considerations. When available in sufficientdetail, service records are a valuable aid to judgment. Theyare most useful when the structures, concr
25、ete proportions,and exposure are similar to those anticipated for the pro-posed work. Petrographic analysis can be used to determinewhether the aggregate to which the service record appliesis sufficiently similar to the proposed aggregate for the ser-vice record to be meaningful. It also provides us
26、eful infor-mation on acceptability of aggregate from a new source. Ascircumstances change or as experience increases, it may bedesirable to reexamine acceptance criteria and to modify orchange them accordingly.Poor performance of hardened concrete discussed inChapter 2 may not be the fault of the ag
27、gregate. For exam-ple, an improper air void system in the cement paste can re-sult in failure of a saturated concrete exposed to freezingand thawing conditions. Chemical agents, such as sulfate,may cause serious deterioration even though the aggregateused is entirely satisfactory.Table 1.1 lists con
28、crete properties and relevant aggregateproperties that are discussed in this guide.Test methods are indicated in Table 1.1 and are listedwith their full title and source in Chapter 8. In many cases,the aggregate properties and test methods listed are not rou-tinely used in specifications for aggrega
29、tes. Their use maybe needed only for research purposes, for investigation ofnew sources, or when aggregate sources are being investi-gated for a special application. Typical values are listedonly for guidance. Acceptable aggregates may have valuesoutside the ranges shown, and conversely, not all agg
30、re-gates within these limits may be acceptable for some uses.Therefore, service records are an important aspect in eval-uating and specifying aggregate sources. Some of the moreroutinely performed tests are described in ACI EducationBulletin E1.A summary of data on aggregate properties and their in-
31、fluence on the behavior of concrete is contained in Signifi-cance of Tests and Properties of Concrete and ConcreteMaking Materials (ASTM, 1994). Information on explora-tion of aggregate sources, production, and rock types is inChapter 2 of the Concrete Construction Handbook (Wad-dell, 1974).NORMAL W
32、EIGHT AND HEAVYWEIGHT AGGREGATES 221R-3Table 1.1Properties of concrete influenced by aggregate propertiesRelevant aggregate property Standard test Typical values Text reference CommentsConcrete propertyDurability: Resistance to freezing and thawingSulfate soundnessASTM C 88Fine agg - 1 to 10%Coarse
33、agg - 1 to 12%2.1.1Magnesium sulfate (MgSO4) gives higher loss percentages than sodium sulfate (NaSO4); test results have not been found to relate well to aggregate performance in con-crete.Resistance to freezing and thawingASTM C 666 and CRD-C-114 - Performance of aggregate in air-entrained concret
34、e by rapid cyclesDurability factor of 10 to 100% 2.1.1Normally only performed for coarse aggre-gate since fine aggregate does not affect con-crete freezing and thawing to any large extent; results depend on moisture condition-ing of coarse aggregates and concrete.ASTM C 682 - Aggregate in concrete,
35、dilation test with slow freezePeriod of frost immunity from 1 to more than 16 weeksResults depend on moisture conditioning of aggregate and concrete. For specimens that do not reach critical dilation in the test period, no specific value can be assigned.AASHTO T 103 - Test of unconfined aggregate in
36、 freeze-thawUsed by some U.S. Departments of Trans-portation; test is not highly standardized between agencies. Results may help judge quality of aggregate in regional area.Absorption ASTM C 127 - Coarse aggre-gate0.2 to 4% 2.1.1Typical values are for natural aggregates. Most blast-furnace slag coar
37、se aggregates are between 4 and 6%, fine aggregate about one percent less.ASTM C 128 - Fine aggregate 0.2 to 2%Some researchers have found a general trend of reduced durability for natural coarse aggregate in concrete exposed to freezing and thawing with increased absorption.Porosity None1 to 10% by
38、 volume for coarse aggregate2.1.1Porosity - The ratio, usually expressed as a percentage, of the volume of voids in a mate-rial to the total volume of the material, including the voids.Pore structure None 2.1.1Mercury intrusion methods and gas or vapor absorption techniques can be used to esti-mate
39、pore size distribution and internal sur-face area of pore spaces.Permeability None 2.1.1Permeability of aggregate materials to air or water is related to pore structure.Texture and structure and lithologyASTM C 295 - Petrographic examinationQuantitative report of rock type and minerals presentEstima
40、tion of the resistance of the aggregate to freezing damage; type of particles that may produce popouts or disintegrationPresence of clay and finesASTM C 117 - Amount by washingFine agg - 0.2 to 6%Coarse agg - 0.2 to 1%3.70Larger amounts of material finer than the 75 m sieve can be tolerated if free
41、of clay min-erals. Does not include clay balls.ASTM D 2419 - Sand equiva-lent50 to 90%Used only for fine aggregate; the presence of active clay may increase water demand or decrease air entrainment.Resistance to degradation ASTM C 131 and C 535 15 to 50% loss 2.1.4These tests impart a good deal on i
42、mpact to the aggregate as well as abrasion; therefore, results not directly related to abrasion test of concrete.C 1137 Degradation of fine aggregateAbrasion resistance ASTM C 418 - Sand blastingVolume of concrete removed per unit area2.1.4These tests are performed on concrete sam-ples containing th
43、e aggregate(s) under inves-tigation and may provide the user with a more direct answer.ASTM C 779 - Three proce-duresDepth of wear with timeNo limit established. Test provides relative differences.ASTM C 944 - Rotating cutterAmount of loss in time abradedNo limit established. Test provides relative
44、differences.ASTM C 1138 - Underwater methodAbrasion loss vs. timeDurability index ASTM D 3744Separate values are obtained for fine and coarse aggregate ranging from 0 to 100This test was developed in California and indicates resistance to the production of clay-like fines when agitated in the presen
45、ce of water.Concrete propertyDurability: Alkali-aggregate reactivityAggregate reactivityASTM C 295 - Petrographic examinationPresence and amount of poten-tially reactive minerals2.1.5For important engineering works. Tests for potential expansion due to aggregate reactiv-ity in moist exposure are oft
46、en conducted using the cement-aggregate combinations expected on the project.ASTM C 227 - Mortar bar expansion0.01 to 0.20% or more after 6 months2.1.5.1Both fine and coarse aggregate can be tested. Coarse aggregates must be crushed to fine aggregate sizes. 221R-4 ACI COMMITTEE REPORTTable 1.1 Prope
47、rties of concrete influenced by aggregate properties (cont.)Relevant aggregate property Standard test Typical values Text reference CommentsASTM C 289 - Chemical methodValues are plotted on a graph 2.1.5.1Degree of risk from alkali-aggregate reactiv-ity is surmised from the position of the points on
48、 the graph. Many slowly reacting aggregates pass this test.ASTM C 586 - Rock cylinder method0.01 to 0.20% or more after 6 months2.1.5.3Used for preliminary screening of potential for alkali-carbonate reactivity.ASTM C 1105 - Length change testUsed to determine the susceptibility to alkali-carbonate
49、reaction.Accelerated concrete prism test Under development in ASTM.Concrete propertyDurability: Resistance to heating and coolingCoefficient of thermal expan-sionCRD-C-125 - Aggregate parti-cles1.0 to 9.0 x 10-6/F2.1.3Normally not a problem for concrete. FHWA has developed a procedure for concrete.Concrete propertyDurability: Fire enduranceLithologyASTM C 295 - Petrographic examinationRock and mineral types present2.1.6 ACI 216R provides data and design charts.Quantity of finesASTM C 117 - Amount by washingF.A - 0.2 to 6%C.A. - 0.2
