1、Designation: D7913/D7913M 14Standard Test Method forBond Strength of Fiber-Reinforced Polymer MatrixComposite Bars to Concrete by Pullout Testing1This standard is issued under the fixed designation D7913/D7913M; the number immediately following the designation indicates theyear of original adoption
2、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. Scope1.1 This test method covers the determination of the bondstrength of fiber-reinfo
3、rced polymer (FRP) composite barsused as reinforcing bars or pre-stressing tendons in concrete.1.2 Two procedures for casting test specimens are provided.The first procedure aligns the bar with the concrete castingdirection. The second procedure aligns the bars transverse tothe concrete casting dire
4、ction.1.3 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformanc
5、ewith the standard.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 applica-bility of regulatory limitations prior to
6、use.2. Referenced Documents2.1 ASTM Standards:2A944 Test Method for Comparing Bond Strength of SteelReinforcing Bars to Concrete Using Beam-End Speci-mensC33/C33M Specification for Concrete AggregatesC39/C39M Test Method for Compressive Strength of Cylin-drical Concrete SpecimensC143/C143M Test Meth
7、od for Slump of Hydraulic-CementConcreteC150/C150M Specification for Portland CementC192/C192M Practice for Making and Curing Concrete TestSpecimens in the LaboratoryC293/C293M Test Method for Flexural Strength of Concrete(Using Simple Beam With Center-Point Loading)C511 Specification for Mixing Roo
8、ms, Moist Cabinets,Moist Rooms, and Water Storage Tanks Used in theTesting of Hydraulic Cements and ConcretesC617/C617M Practice for Capping Cylindrical ConcreteSpecimensD792 Test Methods for Density and Specific Gravity (Rela-tive Density) of Plastics by DisplacementD883 Terminology Relating to Pla
9、sticsD3878 Terminology for Composite MaterialsD5229/D5229M Test Method for MoistureAbsorption Prop-erties and Equilibrium Conditioning of Polymer MatrixComposite MaterialsD7205/D7205M Test Method for Tensile Properties of FiberReinforced Polymer Matrix Composite BarsD7705 Test Method for Alkali Resi
10、stance of Fiber Rein-forced Polymer (FRP) Matrix Composite Bars used inConcrete ConstructionE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical TestingE83 Practice for Verification and Classification of Exten-someter SystemsE122 Practice for Calcul
11、ating Sample Size to Estimate, WithSpecified Precision, the Average for a Characteristic of aLot or ProcessE456 Terminology Relating to Quality and StatisticsE1012 Practice for Verification of Testing Frame and Speci-men Alignment Under Tensile and Compressive AxialForce ApplicationF2203 Test Method
12、 for Linear Measurement Using PrecisionSteel Rule3. Terminology3.1 Terminology in D3878 defines terms relating to highmodulus fibers and their composites. Terminology in D883defines terms relating to plastics. Terminology in E6 definesterms relating to mechanical testing. Terminology in E456 andin P
13、ractice E122 define terms relating to statistics and theselection of sample sizes. In the event of a conflict betweenterms, Terminology in D3878 shall have precedence over theother terminology standards.1This test method is under the jurisdiction of ASTM Committee D30 onComposite Materials and is th
14、e direct responsibility of Subcommittee D30.10 onComposites for Civil Structures.Current edition approved Aug. 15, 2014. Published December 2014. DOI:10.1520/D7913_D7913M-142For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For A
15、nnual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2 Definitions of Terms Specific to This Standard:3.2.1 anchor, na protec
16、tive device placed on one end of abar, between the bar and the grips of the tensile testingmachine, to prevent grip-induced damage. Usually used onbars with irregular surfaces. D7205/D7205M3.2.2 bar, na linear element, often with surface undula-tions or a coating of particles that promote mechanical
17、 inter-lock with concrete.3.2.3 bonded length, nthe length of the test bar that is incontact with concrete.3.2.4 effective circumference, na geometric value repre-senting the circumference of a circle which has an enclosedarea equal to the nominal cross-sectional area of a bar.3.2.5 effective diamet
18、er, na geometric value representingthe diameter of a circle which has an enclosed area equal to thenominal cross-sectional area of a bar.3.2.6 nominal cross-sectional area, na measure of cross-sectional area of a bar, determined over at least one represen-tative length, used to calculate stress.3.2.
19、7 nominal value, na value, existing in name only,assigned to a measurable property for the purpose of conve-nient designation. Tolerances may be applied to a nominalvalue to define an acceptable range for the property.3.2.8 representative length, nthe minimum length of a barthat contains a repeating
20、 geometric pattern that, placed end-to-end, reproduces the geometric pattern of a continuous bar(usually used in reference to bars having surface undulationsfor enhancing interlock with concrete).3.2.9 surface undulation, nvariation in the area,orientation, or shape of the cross-section of a bar alo
21、ng itslength, intended to enhance mechanical interlock between a barand concrete, made by any of a number of processes such as,for example, indentation, addition of extra materials, andtwisting.3.3 Symbols:3.3.1 Anominal cross-sectional area of a bar3.3.2 dbeffective bar diameter per Test Method D72
22、05/D7205M3.3.3 Cbeffective circumference of FRP bar3.3.4 CVsample coefficient of variation3.3.5 ECHORDtensile chord modulus of elasticity in thetest direction per Test Method D7205/D7205M3.3.6 Ftensile force in bar3.3.7 fccompressive strength of concrete3.3.8 lbonded length3.3.9 Lfree length of the
23、loaded-end of the bar3.3.10 Lclength from the top of the embedded bar to thepoint of attachment of the slip measuring device3.3.11 nnumber of specimens3.3.12 rrepeatability limit, the value below which theabsolute difference between two individual test results obtainedunder repeatability conditions
24、may be expected to occur with aprobability of approximately 0.95 (95 %)3.3.13 Scelastic elongation3.3.14 sn-1sample standard deviation3.3.15 xsample mean3.3.16 ximeasured or derived property3.3.17 w/cwater to cement ratio3.3.18 average bond stress4. Summary of Test Method4.1 FRP bars are cast in con
25、crete prisms in one of twoorientations and the concrete is allowed to cure for 28 days.Cured specimens are placed in a test fixture consisting of acompression platen at one end. The loaded-end of the bar isgripped in a tension anchor and loaded in tension until failure.The average bond stress is cal
26、culated as the maximum forceobserved during the test divided by the surface area of the barbonded to the concrete prism.5. Significance and Use5.1 The behavior of the bond between concrete and FRPreinforcing bars is an important performance aspect that hasbeen used in material specifications and des
27、ign standards. Thistest method serves as a means for uniformly preparing speci-mens and testing FRP bar-to-concrete bond, and for providinga standard method to calculate, evaluate and report bondstrength.5.2 This test method for measuring bond strength by pullouttesting is intended for use in labora
28、tory tests in which theprincipal variable is the size or type of FRP bars.NOTE 1This test method should not be used to establish design bondvalues and development lengths for FRP bars embedded in concrete, as itdoes not represent the state of bond stress observed in concrete flexuralmembers reinforc
29、ed with FRPbars. See Test Method A944 for a beam-endtest configuration, used for determining bond stress in steel bars.5.3 This test method is intended to determine the bondbehavior for material specifications, research and development.The bond behavior will be specimen-configuration dependent,which
30、 may affect both analysis and design. The primary testresult is the bond strength of the specimen to normal weightconcrete.5.4 This test method may also be used to determine theconformance of a product or a treatment to a requirementrelating to its effect on the bond developed between FRP barand con
31、crete. The result obtained from this test method shouldbe used only for comparative purposes to compare parametersor variables of bond strength. The method may be used as partof a protocol to establish long-term environmental effects onbond to concrete, including environmental reduction factors forF
32、RP bars embedded in concrete.6. Interferences6.1 The results from the procedures presented are limited tothe material and test factors listed in Section 5.6.2 GrippingThe method of gripping has been known tocause premature tensile failures in bars. Anchors, if used,should be designed in such a way t
33、hat the required tensileD7913/D7913M 142capacity can be achieved without slip throughout the length ofthe anchor during the test.6.3 Concrete Cover SplittingThe concrete prism may splitduring the test, an indication that the force in the bar is too highfor the given specimen configuration. It may be
34、 necessary todecrease the bonded length or increase the prism size for barswith unusually high bond strength. A prism dimension of300 mm 12 in. is suggested in situations where prism splittingoccurs.6.4 Bar Surface CharacteristicsThe average bondstrength is related to the surface characteristics of
35、the bar.Modifications to this texture are likely to affect bond strengthand any such modifications made during specimen preparationshould be reported. If the bar has a representative length that isgreater than the bonded length, the bond strength may varydepending on the location of the bonded secti
36、on in relation tothe representative length.6.5 Concrete Prism FlatnessFlatness of the bearing sur-face of the concrete prism where it meets the steel loading plate(Fig. 1) should be ensured. Non-flat surfaces or lack ofperpendicularity between the concrete surface and the FRP barmay lead to prematur
37、e fracture of the concrete prism due tostress concentrations and may increase the displacement read-ings at the loaded-end of the bars due to deformation of theconcrete prism. For horizontally cast specimens, a rigid moldwith smooth interior surfaces should be used.Acompliant platesuch as a sheet of
38、 plywood or a thin overlay of high-strengthcement or plaster material may be used to accommodateuneven surfaces, see Section 8.6.7.6.6 Concrete StrengthThe bond strength is related to theconcrete compressive strength. Therefore the concrete must becomposed of known constituents and the specimens mus
39、t becured in a controlled environment.6.7 System AlignmentExcessive bending may cause pre-mature failure, as well as a highly inaccurate bond stressdetermination. Every effort should be made to eliminatebending from the test system. Bending may occur due tomisalignment of the bar within the anchor o
40、r grips or due toFIG. 1D7913/D7913M 143lack of perpendicularity between the face of the compressionplaten, the cast face of the prism that mates with the compres-sion platen, and the bar. See Practice E1012 for verification ofspecimen alignment under tensile loading.6.8 Measurement of Cross-Sectiona
41、l AreaThe nominalcross-sectional area of the bar is measured by immersing aprescribed length of the specimen in water to determine itsbuoyant weight per Test Methods D792 and D7205/D7205M.Bar configurations that trap air during immersion (aside fromminor porosity) cannot be assessed using this metho
42、d. Thismethod may not be appropriate for bars that have largevariations in cross-sectional area along the length of the bar.6.9 Environmental Conditions at Time of TestingTestresults may be affected by the laboratory conditions. Testconditions shall be reported.7. Apparatus7.1 Testing MachineThe tes
43、ting machine used shall con-form to the requirements of the sections on Basis ofVerification, Corrections, and Time Interval Between Verifica-tions of Practices E4. Motorized pumps or hand operatedpositive displacement pumps shall be capable of applyingforces at a uniform rate without shock or inter
44、ruption. Thetesting machine shall have a force capacity in excess of thebond capacity of the test specimen.7.1.1 The force indicator on the testing machine shall becalibrated to a range of not greater than 10 times the observedfailure force of the specimen.7.2 Steel RuleLinear measuring device for m
45、easuringbonded length per Test Method F2203.7.3 Drive MechanismThe testing machine with eitherloading-rate or displacement-rate control. The testing machinedrive mechanism shall be capable of imparting to the movablehead a controlled force or displacement rate with respect to thestationary head. The
46、 rate of the movable head shall be capableof being regulated as specified in 11.2.4.7.4 Test FixtureThe test fixture consists of a loading plate,anchor, free-end LVDT (linear variable differential trans-former) clamp and optional loaded-end LVDT clamp (see Fig.1). The loading plate should rest on a
47、support that transfers thereaction from this block to the force indicator of the testingmachine. As an alternative, the force indicator of the testingmachine can be attached to the tension grip at the loaded-endof the bar.7.4.1 Loading PlateThe loading plate should be a ma-chined steel plate at leas
48、t 200 mm 8 in. square and the surfacedimensions of the plate must be larger than the matingdimensions on the specimen. The plate shall be at least 20 mm0.75 in. thick with a surface finish of 1.6 m 64 in. orbetter. The hole drilled through the loading plate should be10 mm 6 5 mm 0.4 in. 6 0.2 in. la
49、rger in diameter than themaximum transverse dimension of the FRP bar. The loadingplate may be fabricated in two parts to accommodate thetesting of specimens fitted with end anchors.7.4.2 If used, the anchor on the loaded-end of the FRP barshall conform to Test Method D7205/D7205M, and may beattached to a tension grip body, to a collet, or to the secondhead of the testing machine, if so equipped.NOTE 2The tensile forces transmitted through the anchor will bebelow those required to rupture the FRP bar in tension. Therefore, it
