ACI 544 2R-1989 Measurement of Properties of Fiber Reinforced Concrete《纤维钢筋混凝土性能测量》.pdf

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1、ACI 544.2R-89 (Reapproved 2009)Measurement of Properties of Fiber Reinforced ConcreteReported by ACI Committee 544Shuaib H. AhmadM. ArockiasamyP. N. BalaguruClaire G. Ball*Hiram P. Ball, Jr.Gordon B. BatsonArnon BenturRobert J. CraigMarvin E. Criswell*Sidney FreedmanRichard E. GalerMelvyn A. Galinat

2、V. S. Gopalaratnam*Antonio Jose GuerraLloyd E. HackmanM. Nadim HassounCharles H. Henager, Sr.*Surendra P. Shah*ChairmanGeorge C. HoffNorman M. HydukRoop L. JindalIver L. JohnsonColin D. Johnston*Charles W. Josifek*David R. Lankard*Brij M. MagoHenry N. Marsh, Jr.Assir MelamedNicholas C. MitchellHenry

3、 J. Molloy*D. R. MorganA. E. Naaman*Stanley L. PaulSeth L. PearlmanV. Ramakrishnan*D. V. ReddyJames I. Daniel*SecretaryThis report outlines existing procedures for specimen preparation ingeneral and discusses testing, workability, flexural strength, tough-ness, and energy absorption. Newly developed

4、 test methods are pre-sented for the first time for impact strength and flexural toughness.The applicability of the following tests to fiber reinforced concrete(FRC) are reviewed: air content, yield, unit weight, compressivestrength, splitting tensile strength, freeze-thaw resistance, shrinkage,cree

5、p, modulus of elasticity, cavitation, erosion, and abrasion resis-tance.Keywords: abrasion tests; cavitation; compression tests; cracking (fracturing);creep properties; energy absorption; erosion; fatigue (materials); fiber rein-forced concretes; flexural strength: freeze-thaw durability; impact tes

6、ts; modu-lus of elasticity; shrinkage; splitting tensile strength ; tests; toughness; work-ability.CONTENTSIntroductionWorkabilityAir content, yield, and unit weightSpecimen preparationCompressive strengthFlexural strengthRalph C. RobinsonE. K. Schrader*Morris SchupackShan SomayajiJ. D. SpeakmanR. N

7、. Swamy*Peter C. TatnallB. L. TilsenGeorge J. Venta*Gary L. Vondran*Methi WecharatanaGilbert R. WilliamsonC. K. WilsonRonald E. WitthohmGeorge Y. WuRobert C. ZellersRonald F. Zollo*ToughnessFlexural fatigue enduranceSplitting tensile strengthImpact resistanceFreeze-thaw resistanceLength change (shri

8、nkage)Resistance to plastic shrinkage crackingCreepModulus of elasticity and Poissons ratioCavitation, erosion, and abrasion resistanceReporting of test dataRecommended referencesINTRODUCTIONThis report applies to conventionally mixed andplaced fiber reinforced concrete (FRC) or fiber rein-forced sh

9、otcrete (FRS) using steel, glass, polymeric, andnatural fibers. It does not relate to thin glass fiber rein-forced cement or mortar products produced by thespray-up process. The Prestressed Concrete Institute, 1ACI Committee Reports, Guides, Standard Practices, andCommentaries are intended for guida

10、nce in designing, plan-ning, executing, or inspecting construction and in preparingspecifications. Reference to these documents shall not be madein the Project Documents. If items found in these documentsare desired to be part of the Project Documents they shouldbe phrased in mandatory language and

11、incorporated into theProject Documents.*Members of the subcommittee that drafted this report.Chairman of the subcommittee that drafted this report.This report supercedes ACI 544.2R-78 (Revised 1983). The revision was ex-tensive. Existing sections were expanded and new sections were added. The or-der

12、 of presentation has been rearranged and references were provided.Copyright 1988, American Concrete Institute.All rights reserved including rights of reproduction and use in any form orby any means, including the making of copies by any photo process, or by anyelectronic or mechanical device, printe

13、d, written, or oral, or recording for soundor visual reproduction or for use in any knowledge or retrieval system or de-vice, unless permission in writing is obtained from the copyright proprietors.544.2R-1544.2R-2 MANUAL OF CONCRETE PRACTICEFig. 1-Slump versus inverted cone time10Glassfibre Reinfor

14、ced Cement Association,2 and ASTMhave prepared recommendations for test methods forthese spray-up materials.The use of fiber reinforced concrete (FRC) haspassed from experimental small-scale applications toroutine factory and field applications involving theplacement of many hundreds of thousands of

15、 cubicyards annually throughout the world. This has createda need to review existing test methods and develop newmethods, where necessary, for determining the proper-ties of FRC. These methods are presented in an effortto standardize procedures and equipment so that testresults from different source

16、s can be compared effec-tively. While it is recognized that the use of proceduresand equipment other than those discussed in this reportmay be employed because of past practices, availabilityof equipment, etc., use of nonstandard tests does notpromote the development or broadening of the database ne

17、eded to quantify consistently properties of thevarious forms of FRC. To date, some progress onstandardization of test methods has been made inNorth America by ASTM and similar organizationsoutside North America, but greater efforts are needed,as is indicated in this report.Although most of the test

18、methods described in thisreport were developed initially for steel fiber reinforcedconcrete, they are applicable to concretes reinforcedwith glass, polymeric, and natural fibers, except whenotherwise noted.The test methods described in this report may insome cases lead to difficulties or problems in

19、 obtainingmeaningful results. In these instances, Committee 544welcomes information on the problems and any modi-fication of equipment or procedures that provides moremeaningful results. This is of particular interest wheretests developed initially for steel FRC are used to mea-sure properties of co

20、ncretes containing other fibers,such as glass, polymeric, or natural fibers.WORKABILITYThe workability of freshly mixed concrete is a mea-sure of its ability to be mixed, handled, transported,and, most importantly, placed and consolidated with aminimal loss of homogeneity and minimal entrappedair. S

21、everal tests are available to assess one or more ofthese characteristics.Slump test (ASTM C 143)The slump test is a common, convenient, and inex-pensive test, but it may not be a good indicator ofworkability for FRC. However, once it has been estab-lished that a particular FRC mixture has satisfacto

22、ryhandling and placing characteristics at a given slump,the slump test may be used as a quality control test tomonitor the FRC consistency from batch to batch.Time of flow through inverted slump cone test(ASTM C 995)This test has been developed specifically to measurethe workability of FRC.3 It effe

23、ctively measures themobility or fluidity of the concrete under internal vi-bration. The test is not suitable for flowable mixturesof FRC, such as produced using high-range water-re-ducing admixtures, because the concrete tends to runthrough the cone without vibration. The slump test isused for monit

24、oring the consistency of these concretes.Fig. 1 shows typical results of this test for conven-tional and FRC mixtures in relation to slump. Even atvery low slump, FRC mixtures respond well to vibra-tion. The flattening of the FRC curve above 2 or 3 in.(50 or 75 mm) slump indicates that for these mix

25、turesthere is no improvement in workability as slumps in-crease beyond about 2 in. (50 mm). Fig. 2 shows a sim-ilar curvilinear relationship between the slump ob-tained under static test conditions and the time of flowobtained with vibration. It also shows a linear relation-ship illustrating direct

26、proportionality between invertedcone time and Vebe time. This suggests that both ofthese vibration-type tests measure essentially the samecharacteristic of the freshly mixed concrete. The exactnature of the relationships of Fig. 1 and 2 will varyfrom one concrete to another depending on aggregatemax

27、imum size and gradation, fiber concentration, typeand aspect ratio, and air content.The inverted cone test can be used to compare FRCto conventional mixtures with similar slump values. Forexample, at a 2 in. (50 mm) slump, a 3/8 in. (10 mm)aggregate FRC mixture has substantially less flow timethan a

28、 3/4 in. (19 mm) aggegate mixture at the sameslump (Fig. 1). This demonstrates that although theslumps of these two mixtures are similar, the workabil- PROPERTIES OF FIBER REINFORCED CONCRETE 544.2R-3ity of the FRC mixture was much better. The advan-tage of the inverted slump cone test over the slum

29、p testis that it takes into account the mobility of concrete,which comes about because of vibration.Vebe testThe Vebe consistometer described in the BritishStandards Institution standard BS 1881, “Methods ofTesting Concrete, Part 2,” measures the behavior ofconcrete subjected to external vibration a

30、nd is accept-able for determining the workability of concrete placedusing vibration, including FRC. It effectively evaluatesthe mobility of FRC, that is, its ability to flow undervibration, and helps to assess the ease with which en-trapped air can be expelled. The Vebe test is not asconvenient for

31、field use as either the slump or invertedcone test because of the size and weight of the equip-ment.AIR CONTENT, YIELD, AND UNIT WEIGHTStandard ASTM air content test equipment and pro-cedures for conventional concrete can be used for de-termining the air content, yield, and unit weight ofFRC (ASTM C

32、 138, C 173, and C 231). The concretesamples should be consolidated using external or inter-nal vibration as permited by ASTM C 31 and C 192,and not by rodding. Rodding may be used when a highflow consistency has been produced by the use of high-range water-reducing admixtures.SPECIMEN PREPARATIONIn

33、 general, procedures outlined in ASTM C 31, C 42,C 192, and C 1018 should be followed for specimenpreparation. Additional guidance for preparing fiberreinforced shotcrete specimens is available in ACI506.2-77 (Revised 1983). Test specimens should be pre-pared using external vibration whenever possib

34、le.Internal vibration is not desirable and rodding is notacceptable, as these methods of consolidation may pro-duce preferential fiber alignment and nonuniform dis-tribution of fibers. Although external vibration mayproduce some alignment of fibers, the amount ofalignment produced in the short durat

35、ion vibration re-quired for consolidation of test specimens is of negli-gible influence.The method, frequency, amplitude, and time of vi-bration should be recorded. Test specimens having adepth of 3 in. (75 mm) or less should be cast in a singlelayer to avoid fiber orientation and fiber-free planes.

36、Two layers should be used for specimens of depthgreater than 3 in. (75 mm) with each layer being vi-brated. Care should be taken to avoid placing the con-crete in a manner that produces a lack of fiber conti-nuity between successive placements. The preferredplacement method is to use a wide shovel o

37、r scoop andplace each layer of concrete uniformly along the lengthof the mold. Any preferential fiber alignment by themold surfaces can influence test results, particularly forsmall cross sections with long fibers. Generally, thesmallest specimen dimension should be at least threeFig. 2-Relationship

38、 between slump, Vebe time, andinverted cone time 3times the larger of the fiber length and the maximumaggregate size. Recommendations for selecting speci-men size and preparing test specimens for flexuraltoughness tests are given in ASTM C 1018.COMPRESSIVE STRENGTHASTM compressive strength equipment

39、 and proce-dures (ASTM C 31, C 39, and C 192) used for conven-tional concrete can be used for FRC. The cylindersshould be 6 x 12 in. (150 x 300 mm) in size and shouldbe made using external vibration or a 1 in. (25 mm)nominal width internal vibrator. External vibration ispreferred since an internal v

40、ibrator may adversely in-fluence random fiber distribution and alignment.The presence of fibers alters the mode of failure ofcylinders by making the concrete less brittle. Signifi-cant post-peak strength is retained with increasing de-formation beyond the maximum load. Fibers usuallyhave only a mino

41、r effect on compressive strength,slightly increasing or decreasing the test result. Sincesmaller cylinders give higher strengths for conventionalconcrete and promote preferential fiber alignment inFRC, small cylinders with long fibers may give unreal-istically high strengths. Cubes may also be used

42、forcompressive strength tests, but few reference data areavailable for such specimens and the relationship be-tween cube strength and cylinder strength has not beendetermined for FRC.FLEXURAL STRENGTHThe flexural strength of FRC may be determined un-der third-point loading using ASTM C 78 or C 1018,

43、 orby center-point loading using ASTM C 293. Third-point loading is the preferred technique. If only maxi-mum flexural strength is of interest, ASTM C 78 orC 293 can be used. Maximum flexural strength is cal-culated at the section of maximum moment corre- 544.2R-4MANUAL OF CONCRETE PRACTICEFig. 3-Fl

44、exural strength-Calculated in accordancewith ASTM C 78 or C 293 using the maximum loadsponding to the peak fiber stress in tension based on theassumption of elastic behavior, as shown in Fig. 3. Iftoughness or load-deflection behavior is also of inter-est, ASTM C 1018 can be used. However, results o

45、b-tained in load-controlled testing according to ASTMC 78 may differ from those obtained using the deflec-tion-controlled procedures of ASTM C 1018.4At least three specimens should be made for each testaccording to the “Specimen Preparation” section ofthis report and ASTM C 1018. For thick sections,

46、specimen width and depth should equal or exceed threetimes both the fiber length and the nominal dimensionof the maximum size aggregate. When the applicationfor the FRC involves a thickness less than this, e.g.,overlays, specimens with a depth equal to the actualsection thickness should be prepared.

47、 These should betested as cast, rather than turned 90 deg as is requiredfor standard-size beams, to evaluate the effects of pref-erential fiber alignment to be representative of the FRCin practice.When it is possible to meet the width and depth re-quirements of three times the fiber length and aggre

48、-gate size, a set of specimens with a preferred size of 4 x4 x 14 in. (100 x 100 x 350 mm) should be made andtested with third-point loading to allow comparison ofresults with a large base of available data from otherprojects that have used this as the standard test speci-men. Otherwise, the size of

49、 specimens for thick sec-tions should conform to the requirements of ASTMC 1018. If the width or depth of a specimen is less thanthree times the fiber length, preferential fiber align-ment tends to increase the measured flexural strength.This increase is representative only when a similar pref-erential fiber alignment increase can be expected for theFRC in use.The relationship between flexural strength and directtensile strength has