1、Designation: D7705/D7705M 12Standard Test Method forAlkali Resistance of Fiber Reinforced Polymer (FRP) MatrixComposite Bars used in Concrete Construction1This standard is issued under the fixed designation D7705/D7705M; 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. Scope1.1 This test method covers the procedure for evaluating thealkali resis
3、tance of FRP bars used as reinforcing bars inconcrete. Alkali resistance is measured by subjecting the FRPbars to an aqueous alkali environment, with or without sus-tained tensile stress, and then testing them to failure in tensionaccording to Test Method D7205/D7205M. This standardpresents three pr
4、ocedures conducted at a moderately elevatedtemperature of 60C (140F), each defining different loadingconditions. The test method is also appropriate for use withlinear segments of FRP reinforcements cut from two- orthree-dimensional reinforcing grid.1.2 The values stated in either inch-pound units o
5、r SI unitsshall be regarded separately as the standard. The inch-poundunits are shown in the parenthesis. The values stated in eachsystem are not exact equivalents; therefore each system shallbe used independently of each other. Combining values fromthe two systems may result in non-conformance.1.3
6、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 use.2. Referenced Docum
7、ents2.1 ASTM Standards:2A615/A615M Specification for Deformed and PlainCarbon-Steel Bars for Concrete ReinforcementC192/C192M Practice for Making and Curing ConcreteTest Specimens in the LaboratoryC496/C496M Test Method for Splitting Tensile Strength ofCylindrical Concrete SpecimensC511 Specificatio
8、n for Mixing Rooms, Moist Cabinets,Moist Rooms, and Water Storage Tanks Used in theTesting of Hydraulic Cements and ConcretesC1260 Test Method for Potential Alkali Reactivity of Ag-gregates (Mortar-Bar Method)C1293 Test Method for Determination of Length Change ofConcrete Due to Alkali-Silica Reacti
9、onD618 Practice for Conditioning Plastics for TestingD883 Terminology Relating to PlasticsD3878 Terminology for Composite MaterialsD7205/D7205M Test Method for Tensile Properties of Fi-ber Reinforced Polymer Matrix Composite BarsE4 Practices for Force Verification of Testing MachinesE6 Terminology R
10、elating to Methods of Mechanical TestingE70 Test Method for pH of Aqueous Solutions With theGlass ElectrodeE456 Terminology Relating to Quality and Statistics3. Terminology3.1 Terminology in D3878 defines terms relating to high-modulus fibers and their composites. Terminology in D883defines terms re
11、lating to plastics. Terminology in E6 definesterms relating to mechanical testing. Terminology in E456defines terms relating to statistics and the selection of samplesizes. In the event of a conflict between terms, Terminology inD3878 shall have precedence over the other terminologystandards.3.2 Def
12、initions of Terms Specific to This Standard:3.2.1 bar, na linear element, with a substantially roundcross-section, often with surface undulations or a coating ofparticles that promote mechanical interlock with concrete.3.2.2 nominal cross-sectional area, na measure of cross-sectional area of a bar,
13、determined over at least one represen-tative length, used to calculate stress.3.2.3 representative length, nthe minimum length of a barthat contains a repeating geometric pattern that, placed end-to-end, reproduces the geometric pattern of a continuous bar(usually used in reference to bars having su
14、rface undulationsfor enhancing interlock with concrete).3.2.4 standard cross-sectional area, nthe cross-sectionalarea of a standard numbered steel concrete reinforcing bar asgiven in Specification A615/A615M, Table 1.1This test method is under the jurisdiction of ASTM Committee D30 onComposite Mater
15、ials and is the direct responsibility of Subcommittee D30.05 onStructural Test Methods.Current edition approved March 1, 2012. Published April 2012. DOI: 10.1520/D7705_D7705M-12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org.
16、For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2.5 surface undulation, nvariation in the area, orienta-tion, or s
17、hape of cross-section of a bar along its length,intended to enhance mechanical interlock between a bar andconcrete, made by any of a number of processes such as, forexample, indentation, addition of extra materials, and twisting.3.2.6 traveler, na short bar segment, subject to the sameenvironmental
18、conditions as the tension specimens, used formass change measurements in Procedure A.3.3 Symbols:3.3.1 Ftu0tensile capacity before conditioning (but afterpre-conditioning), a baseline established according to TestMethod D7205/D7205M.3.3.2 Ftu1tensile capacity after conditioning and post-conditioning
19、, established according to Test Method D7205/D7205M.3.3.3 Rettensile capacity retention, compared to the base-line measurement measured according to Test Method D7205/D7205M, expressed as a percentage.3.3.4 W0mass of traveler specimen before conditioning.3.3.5 W1Amass of traveler specimen after post
20、-conditioning.3.3.6 W1Bmass of traveler specimen before post-conditioning.4. Summary of Test Method4.1 This test method provides standardized requirement fordetermining the alkali resistance of FRP bars under laboratoryconditions. The principal variables used in the laboratory testsare the nature an
21、d concentration of the alkaline solution, andthe sustained force level. Three procedures are availabledepending on the goals of the test.4.1.1 Procedure A is designed to test the alkali resistance ofFRP specimens with no tensile force applied. Four sets ofspecimens are immersed in an alkaline soluti
22、on without tensileforce. Each set of specimens is immersed for a different periodof time: 1, 2, 3, or 6 months. After each of the requiredconditioning times, one set of specimens is removed from thealkaline solution and tested in tension. The test control param-eters are the pH value and temperature
23、 of the alkaline solutionand the immersion time. Procedure A also determines the massuptake (or loss) of the specimens using travellers.4.1.2 Procedure B is designed to test the alkali resistance ofFRP specimens with sustained tensile force. Four sets ofspecimens are immersed in an alkaline solution
24、 under asustained tensile force. Each set of specimens is conditionedfor a different period of time: 1, 2, 3, or 6 months. After eachof the required conditioning times, one set of specimens isremoved from the alkaline solution and tested in tension. Thetest parameters are the sustained force level,
25、the pH value, andthe immersion time.4.1.3 Procedure C is designed to test the alkali resistance ofFRP specimens embedded in moist concrete under sustainedtensile force. Four sets of specimens are embedded in moistconcrete and held under a sustained tensile force. Each set ofspecimens is conditioned
26、for a different period of time: 1, 2, 3,or 6 months. After each of the required conditioning times, oneset of specimens are removed from the conditioning environ-ment and tested in tension. The test parameters are thesustained force level, the pH value and the embedment time.4.2 The level of sustain
27、ed loading (for Procedures B and C)is not specified as part of the test method. If service loadconditions are not known, the sustained tensile stress inglass-fiber FRP bars shall be set to induce an initial tensilestrain equal to 2000 microstrain. The level of sustained stressshall be reported.5. Si
28、gnificance and Use5.1 This test method is intended to determine alkalineresistance data for material specifications, research and devel-opment, quality assurance, and structural design and analysis.Depending on the procedure and test matrix, the primary testresults are the mass change and tensile ca
29、pacity retention of thetest specimen, which are important factors to be considered inthe use of FRP reinforcing bars. Procedures A and B areaccelerated tests, substituting an alkaline aqueous environmentfor the presence of concrete porewater. Procedure C can beused to establish the accelerating effe
30、ct of Procedure B.5.1.1 Procedure A is appropriate for rapid screening of FRPbars for alkali resistance.5.1.2 Procedure B is appropriate for characterizing thealkali resistance of FRP bars under sustained mechanicalloading in a standard aqueous alkaline environment intended torepresent the concrete
31、porewater.5.1.3 Procedure C is appropriate for characterizing thealkali resistance of FRP bars under sustained mechanicalloading in Portland cement concrete.6. Interferences6.1 Test ConditionsHygro-thermal degradation of FRPcomposite materials is highly dependent upon environmentalconditions such as
32、, for example, temperature, humidity, andchemical agents. The FRP bars shall be conditioned undertightly controlled and monitored conditions. For bars condi-tioned in aqueous solutions, the conditioning solutions maychange over time due to evaporation. The quantity and pH ofthe solution shall be mai
33、ntained by the addition of hydroxidesand tap water as necessary to maintain the required pH level.6.2 Additional interferences associated with execution ofthe tension testing can be found in Test Method D7205/D7205M.7. Apparatus7.1 BalanceFor Procedure A, an analytical balance withan accuracy of 0.1
34、 mg for traveler specimens weighing 50 g orless, and with an accuracy of 1 mg for traveler specimensweighing more than 50 g.7.2 For Procedures B and C, a sustained loading apparatuscapable of applying and maintaining a force on the specimenwithin 61% of the desired sustained force.7.3 Test Apparatus
35、A tension testing apparatus with aforce capacity in excess of the tensile capacity of the specimenand calibrated according to Practices E4.7.4 AnchorsAnchors shall be in accordance with TestMethod D7205/D7205M.7.5 For Procedures A and B, an apparatus for measuring pHof aqueous solutions in accordanc
36、e with Test Method E70.7.6 Environmental Test ChamberAn environmental testchamber capable of maintaining the required temperature toD7705/D7705M 122within 6 3C 6 5F. In addition, the chamber may have tobe capable of maintaining environmental conditions such asfluid exposure during the test.NOTE 1For
37、 Procedures A and B, it is acceptable to substitute atemperature-controlled bath for the environmental chamber.8. Test Specimens8.1 FRP bar specimens shall be representative of the lot orbatch being tested. In general, test specimens shall not besubjected to any processing beyond manufacturing. For
38、grid-type FRP bars, linear test specimens may be prepared bycutting away extraneous material in such a way as not to affectthe performance of the tested part.8.2 During the sampling and preparation of test specimens,all deformation, heating, outdoor exposure to ultraviolet light,and other conditions
39、 possibly causing changes to materialproperties of the specimen shall be avoided.8.3 The length of the specimens shall be in accordance withTest Method D7205/D7205M, Table A1.1.8.4 The cross-sectional area of the specimen shall be deter-mined in accordance with either of the two methods describedin
40、Test Method D7205/D7205M: nominal area or standardarea.8.5 The number of test specimens in each set for pre- andpost-conditioned testing shall not be less than five. Eachspecimen shall be clearly labeled with identifying markings.8.6 Coat the ends of the bars and the ends and transverseelements of g
41、rids with room temperature curing epoxy resin toprevent the infiltration of solution via these cuts.Allow resin tocure completely before immersion. This provision also appliesto traveler specimens for weight-change measurements.8.7 The alkaline solution in Procedures A and B shall be acomposition re
42、presentative of the porewater inside Portlandcement concrete. The suggested composition of alkaline solu-tion consists of 118.5 g of Ca(OH)2, 0.9 g of NaOH and 4.2 gof KOH in 1 liter (33.8 fl. oz.) of tap water. The solution shallhave an initial pH value of 12.6 to 13.0 as measured by TestMethod E70
43、. The alkaline solution shall be covered before andduring the test to prevent interaction with atmospheric CO2andto prevent evaporation.9. Calibration9.1 The accuracy of all measuring equipment shall havecertified calibrations that are current at the time of use of theequipment.10. Conditioning10.1
44、Pre-Conditioning for all specimensAll specimens,including those used for baseline measurements and travelerspecimens for weight-change measurements shall be pre-conditioned in accordance with Procedure B of Practice D618.For Procedure A, traveler specimens should be weighed beforepre-conditioning.10
45、.2 Specimens for Procedure A shall be immersed in thealkaline solution at 60 6 3oC (140 6 5oF) for exposure timesof 1, 2, 3, or 6 months, unless longer exposure periods arespecified. After the allotted times, the specimens shall beremoved from the alkaline solution and thoroughly washed intap water.
46、10.3 Specimens for Procedure B shall be installed withanchoring devices at both ends in accordance with Test MethodD7205/D7205M,AppendixA. The test section of the specimenshall be immersed in the alkaline solution inside an environ-mental cabinet or container holding the alkaline solutions andhaving
47、 a constant temperature of 60 6 3oC (140 6 5oF). Thespecimen shall be held in a loading fixture, subjecting the barto a constant tensile sustained force for exposure times of 1, 2,3, or 6 months, unless longer exposure periods are specified.After the allotted times, the specimens shall be unloaded a
48、ndremoved from the alkaline solution.10.4 Specimens for Procedure C shall be conditioned byembedding the test section of the specimens in moist concretecylinders as shown in Fig. 1. The cylinders should have adiameter of at least 150 mm (6 in.) and be of sufficient diameterto provide at least 62 mm
49、(2.5 in.) of clear cover from thesurface of the concrete to the surface of the bar. The length ofthe cylinder shall be at least 200 mm (8 in.) but should not beless than 15 times the diameter of the FRP bar. For FRP bars intwisted strand form, the cylinder length should also be greaterthan the strand pitch.10.4.1 Specimens shall be cured for 28 days in tap water atroom temperature. Anchors shall be installed at both ends ofthe specimen in accordance with Appendix A of Test MethodFIG. 1 Dimensions of Concrete CylinderD7705/D7705M 123D7205/D7205M. Anchors may
