1、Designation: C1609/C1609M 10 C1609/C1609M 12Standard Test Method forFlexural Performance of Fiber-Reinforced Concrete (UsingBeam With Third-Point Loading)1This standard is issued under the fixed designation C1609/C1609M; the number immediately following the designation indicates theyear of original
2、adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method evaluates the flexural performance of fiber-reinfo
3、rced concrete using parameters derived from theload-deflection curve obtained by testing a simply supported beam under third-point loading using a closed-loop, servo-controlledtesting system.1.2 This test method provides for the determination of first-peak and peak loads and the corresponding stress
4、es calculated byinserting them in the formula for modulus of rupture given in Eq 1. It also requires determination of residual loads at specifieddeflections, the corresponding residual strengths calculated by inserting them in the formula for modulus of rupture given in Eq1 (see Note 1). It provides
5、 for determination of specimen toughness based on the area under the load-deflection curve up to aprescribed deflection (see Note 2) and the corresponding equivalent flexural strength ratio.NOTE 1Residual strength is not a true stress but an engineering stress computed using simple engineering bendi
6、ng theory for linear elastic materialsand gross (uncracked) section properties.NOTE 2Specimen toughness expressed in terms of the area under the load-deflection curve is an indication of the energy absorption capability of theparticular test specimen, and its magnitude depends directly on the geomet
7、ry of the test specimen and the loading configuration.1.3 This test method utilizes two preferred specimen sizes of 100 by 100 by 350 mm 4 by 4 by 14 in. tested on a 300 mm12 in. span, or 150 by 150 by 500 mm 6 by 6 by 20 in. tested on a 450 mm 18 in. span. A specimen size different from thetwo pref
8、erred specimen sizes is permissible.1.4 UnitsThe values stated in either SI units or inch-pound units are to be regarded separately as standard. The values statedin each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining valuesfrom the two
9、 systems may result in non-conformance with the standard.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicabilit
10、y of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C31/C31M Practice for Making and Curing Concrete Test Specimens in the FieldC42/C42M Test Method for Obtaining and Testing Drilled Cores and Sawed Beams of ConcreteC78 Test Method for Flexural Strength of Concrete (Us
11、ing Simple Beam with Third-Point Loading)C125 Terminology Relating to Concrete and Concrete AggregatesC172 Practice for Sampling Freshly Mixed ConcreteC192/C192M Practice for Making and Curing Concrete Test Specimens in the LaboratoryC823 Practice for Examination and Sampling of Hardened Concrete in
12、 ConstructionsC1140 Practice for Preparing and Testing Specimens from Shotcrete Test Panels3. Terminology3.1 DefinitionsThe terms used in this test method are defined in Terminology C125.3.2 Definitions of Terms Specific to This Standard:1 This test method is under the jurisdiction of ASTM Committee
13、 C09 on Concrete and Concrete Aggregates and is the direct responsibility of Subcommittee C09.42 onFiber-Reinforced Concrete.Current edition approved March 1, 2010Dec. 1, 2012. Published April 2010January 2013. Originally approved in 2005. Last previous edition approved in 20072010 asC1609/C1609M07.
14、10. DOI: 10.1520/C1609_C1609M-10.10.1520/C1609_C1609M-12.2 For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.T
15、his document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior edit
16、ions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959
17、. United States13.2.1 end-point deflection, nthe deflection value on the load-deflection curve equal to 1150 of the span length, or a larger valueas specified at the option of the specifier of tests.3.2.2 first-peak load, P1, nthe load value at the first point on the load-deflection curve where the
18、slope is zero.3.2.3 first-peak deflection, 1, nthe net deflection value on the load-deflection curve at first-peak load.3.2.4 first-peak strength f1, nthe stress value obtained when the first-peak load is inserted in the formula for modulus of rupturegiven in Eq 1.3.2.5 load-deflection curve, nthe p
19、lot of load versus net deflection of a flexural beam specimen loaded to the end-pointdeflection.3.2.6 net deflection, nthe deflection measured at mid-span of a flexural beam specimen exclusive of any extraneous effectsdue to seating or twisting of the specimen on its supports or deformation of the s
20、upport and loading system.3.2.7 peak load, PP,nthe maximum load on the load-deflection curve.3.2.8 peak-load deflection, P,nthe net deflection value on the load-deflection curve at peak load.3.2.9 peak strength, fP,nthe stress value obtained when the peak load is inserted in the formula for modulus
21、of rupture givenby Eq 1.3.2.10 Dnominal depth of the beam specimen in mm.NOTE 3To simplify nomenclature, the nominal beam depth is shown in units of mm for both the SI and inch-pound version of this test method.3.2.11 Lspan length or distance between the supports.3.2.12 residual load, P600D , nthe l
22、oad value corresponding to a net deflection of L/600 for a beam of nominal depth D.3.2.13 residual load, P150D , nthe load value corresponding to a net deflection of L/150 for a beam of nominal depth D.3.2.14 residual strength, f600D , nthe stress value obtained when the residual load P600D is inser
23、ted in the formula for modulus ofrupture given in Eq 1.3.2.15 residual strength, f150D , nthe stress value obtained when the residual load P150D is inserted in the formula for modulus ofrupture given in Eq 1.3.2.16 specimen toughness, T150D , ntoughness of beam specimen of nominal depth D at a net d
24、eflection of L/150.3.2.17 equivalent flexural strength ratio, RT, 150D , nthe value obtained when the specimen toughness T150D is inserted in Eq 3.NOTE 4The equivalent flexural strength ratio is calculated as the ratio of the weighted equivalent load up to a net deflection of L/150 over thefirst-pea
25、k load multiplied by 100. The RT, 150150 value is equivalent to the Re,3 value defined in the Technical Report No. 34 of the Concrete Society.34. Summary of Test Method4.1 Molded or sawn beam specimens having a square cross-section of fiber-reinforced concrete are tested in flexure using athird-poin
26、t loading arrangement similar to that specified in Test Method C78 but incorporating a closed-loop, servo-controlledtesting system and roller supports that are free to rotate on their axes. Load and net deflection are monitored and recorded to anend-point deflection of at least 1150 of the span. Dat
27、a are recorded and plotted by means of an X-Y plotter, or they are recordeddigitally and subsequently used to plot a load-deflection curve. Points termed first-peak, peak, and residual loads at specifieddeflections are identified on the curve, and are used to calculate flexural performance parameter
28、s.5. Significance and Use5.1 The first-peak strength characterizes the flexural behavior of the fiber-reinforced concrete up to the onset of cracking, whileresidual strengths at specified deflections characterize the residual capacity after cracking. Specimen toughness is a measure of theenergy abso
29、rption capacity of the test specimen. The appropriateness of each parameter depends on the nature of the proposedapplication and the level of acceptable cracking and deflection serviceability. Fiber-reinforced concrete is influenced in differentways by the amount and type of fibers in the concrete.
30、In some cases, fibers may increase the residual load and toughness capacityat specified deflections while producing a first-peak strength equal to or only slightly greater than the flexural strength of theconcrete without fibers. In other cases, fibers may significantly increase the first-peak and p
31、eak strengths while affecting a relativelysmall increase in residual load capacity and specimen toughness at specified deflections.5.2 The first-peak strength, peak strength, and residual strengths determined by this test method reflect the behavior offiber-reinforced concrete under static flexural
32、loading. The absolute values of energy absorption obtained in this test are of littledirect relevance to the performance of fiber-reinforced concrete structures since they depend directly on the size and shape of thespecimen and the loading arrangement.3 “Concrete Industrial Ground FloorsA Guide to
33、Design and Construction,” Technical Report 34, 3rd edition, Concrete Society, Slough, United Kingdom, 2003.C1609/C1609M 1225.3 The results of this test method may be used for comparing the performance of various fiber-reinforced concrete mixturesor in research and development work. They may also be
34、used to monitor concrete quality, to verify compliance with constructionspecifications, obtain flexural strength data on fiber-reinforced concrete members subject to pure bending, or to evaluate the qualityof concrete in service.5.4 The results of this standard test method are dependent on the size
35、of the specimen.NOTE 5The results obtained using one size molded specimen may not correspond to the performance of larger or smaller molded specimens, concretein large structural units, or specimens sawn from such units. This difference may occur because the degree of preferential fiber alignment be
36、comes morepronounced in molded specimens containing fibers that are relatively long compared with the cross-sectional dimensions of the mold. Moreover, structuralmembers of significantly different thickness experience different maximum crack widths for a given mid-span deflection with the result tha
37、t fibers undergodifferent degrees of pull-out and extension.6. Apparatus6.1 Testing MachineThe testing machine shall be capable of servo-controlled operation where the net deflection of the centerof the beam is measured and used to control the rate of increase of deflection. Testing machines that us
38、e stroke displacement controlor load control are not suitable for establishing the portion of the load-deflection curve immediately after first-peak. The loadingand specimen support system shall be capable of applying third-point loading to the specimen without eccentricity or torque. Thefixtures sp
39、ecified in Test Method C78 are suitable with the qualification that supporting rollers shall be able to rotate on their axesand shall not be placed in grooves or have other restraints that prevent their free rotation.6.2 Deflection-Measuring EquipmentDevices such as electronic transducers or electro
40、nic deflection gages shall be located ina manner that ensures accurate determination of the net deflection at the mid-span exclusive of the effects of seating or twistingof the specimen on its supports. One acceptable arrangement employs a rectangular jig, which surrounds the specimen and isclamped
41、to it at mid-depth directly over the supports (Figs. 1 and 2). Two electronic displacement transducers or similar digitalor analog devices mounted on the jig at mid-span, one on each side, measure deflection through contact with appropriate bracketsattached to the specimen. The average of the measur
42、ements represents the net deflection.6.3 Data Recording SystemAn X-Y plotter coupled directly to electronic outputs of load and deflection is an acceptable meansof obtaining the relationship between load and net deflectionthat is, the load-deflection curve. A data acquisition system capableof digita
43、lly recording and storing load and deflection data at a sampling frequency of at least 2.5 Hz is an acceptable alternative.After a net deflection of L/900 has been exceeded, it is permissible to decrease the data acquisition sampling and recordingfrequency to 1 Hz.at least 2 Hz. This applies regardl
44、ess of the rate of deflection used to load the specimen.NOTE 6For X-Y plotters, accurate determination of the area under the load-deflection curve and the loads corresponding to specified deflections isonly possible when the scales chosen for load and deflection are reasonably large. A load scale ch
45、osen such that 25 mm 1 in. corresponds to a flexuralstress of the order of 1 MPa 150 psi, or no more than 20 % of the estimated first-peak strength, is recommended. A recommended deflection scale isto use 25 mm 1 in. to represent about 10 % of the end-point deflection of 1150 of the span, which is 2
46、 mm 0.08 in. for a 350 by 100 by 100 mm 14by 4 by 4 in. specimen size, and 3 mm 0.12 in. for a 500 by 150 by 150 mm 20 by 6 by 6 in. specimen size. When data are digitally stored, the testparameters may be determined directly from the stored data or from a plot of the data. In the latter case, use a
47、 plot scale similar to that recommendedfor an X-Y plotter.FIG. 1 Arrangement to Obtain Net Deflection by Using Two Transducers Mounted on Rectangular Jig Clamped to Specimen DirectlyAbove SupportsC1609/C1609M 1237. Sampling, Test Specimens, and Test Units7.1 General RequirementsThe nominal maximum s
48、ize of aggregate and cross-sectional dimensions of test specimens shall bein accordance with Practice C31/C31M or Practice C192/C192M when using molded specimens, or in accordance with TestMethod C42/C42M when using sawn specimens, provided that the following requirements are satisfied:7.1.1 The len
49、gth of test specimens shall be at least 50 mm 2 in. greater than three times the depth, and in any case not lessthan 350 mm 14 in. The length of the test specimen shall not be more than two times the depth greater than the span.7.1.2 The tolerances on the cross-section of the test specimens shall be within 6 2 %. The test specimens shall have a squarecross-section within these tolerances.7.1.3 The width and depth of test specimens shall be at least three times the maximum fiber length.7.1.4 When the specimen size is
