ASTM A767 A767M-2009 Standard Specification for Zinc-Coated (Galvanized) Steel Bars for Concrete Reinforcement《钢筋混凝土用镀锌钢筋的标准规范》.pdf

1、Designation: A 767/A 767M 09Standard Specification forZinc-Coated (Galvanized) Steel Bars for ConcreteReinforcement1This standard is issued under the fixed designationA 767/A 767M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, th

2、e year of last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope*1.1 This specification covers

3、steel reinforcing bars withprotective zinc coatings applied by dipping the properlyprepared reinforcing bars into a molten bath of zinc.1.2 This specification is applicable for orders in eitherinch-pound units (as Specification A 767) or SI units (asSpecification A 767M).1.3 The values stated in eit

4、her SI or inch-pound units are tobe regarded as standard. Within the text, the inch-pound unitsare shown in brackets. The values stated in each system are notexact equivalents. Therefore, each system must be used inde-pendently of the other. Combining values from the two systemsmay result in nonconf

5、ormance with this specification.2. Referenced Documents2.1 ASTM Standards:2A 90/A 90M Test Method for Weight Mass of Coating onIron and Steel Articles with Zinc or Zinc-Alloy CoatingsA 615/A 615M Specification for Deformed and PlainCarbon-Steel Bars for Concrete ReinforcementA 706/A 706M Specificati

6、on for Low-Alloy Steel De-formed and Plain Bars for Concrete ReinforcementA 780/A 780M Practice for Repair of Damaged and Un-coated Areas of Hot-Dip Galvanized CoatingsA 996/A 996M Specification for Rail-Steel and Axle-SteelDeformed Bars for Concrete ReinforcementB6 Specification for ZincB 487 Test

7、Method for Measurement of Metal and OxideCoating Thickness by Microscopical Examination of CrossSectionE 376 Practice for Measuring Coating Thickness byMagnetic-Field or Eddy-Current (Electromagnetic) Exami-nation Methods2.2 ACI Specification:3ACI 301 Specifications for Structural Concrete3. Orderin

8、g Information3.1 It shall be the responsibility of the purchaser to specifyall requirements that are necessary for material ordered to thisspecification. Such requirements shall include, but are notlimited to, the following:3.1.1 Quantity of bars,3.1.2 Size of bars,3.1.3 Reinforcing bar specificatio

9、n (ASTM designation andyear of issue) and grade,3.1.4 Class of coating,3.1.5 Galvanization before or after fabrication, andNOTE 1A typical ordering description is as follows: Deformed Grade420 bars to ASTM A 615M-_; 1600 m, No. 19, 8 m long in securedlifts; zinc-coated (galvanized) to ASTM A 767M-_;

10、 including Class 1coating, and galvanization after fabrication.Deformed Grade 60 bars to ASTM A 615-_; 4000 linear ft, No. 6,20 ft, 0 in. long in secured lifts; zinc-coated (galvanized) to ASTMA 767-_, including Class 1 coating, and galvanization after fabrica-tion.4. Galvanizing4.1 Handling:4.1.1 T

11、he galvanizer shall be permitted to subject the newlycoated steel reinforcing bars to air or steam wiping to removeexcess zinc from the bars. After the wiping, the coated steelreinforcing bars shall meet the minimum coating massweight.NOTE 2During the wiping process, care should be taken to maintain

12、a uniformly thick coating around the perimeter of the bar.1This specification is under the jurisdiction of ASTM Committee A01 on Steel,Stainless Steel and Related Alloys and is the direct responsibility of SubcommitteeA01.05 on Steel Reinforcement.Current edition approved July 1, 2009. Published Aug

13、ust 2009. Originallyapproved in 1979. Last previous edition approved in 2005 as A 767/A 767M 05.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Docume

14、nt Summary page onthe ASTM website.3Available from American Concrete Institute (ACI), P.O. Box 9094, FarmingtonHills, MI 48333-9094, http:/www.concrete.org.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Consho

15、hocken, PA 19428-2959, United States.4.1.2 It shall be the responsibility of the galvanizer tomaintain identity of the reinforcing bars throughout the galva-nizing process and to the point of shipment.4.2 Mass Weight of Coating and Test:4.2.1 This specification includes two classes of coatingmass we

16、ight. The mass weight of zinc coating based onactual area of the bar shall conform to the requirements shownin Table 1.NOTE 3The nominal diameter of a deformed bar is equivalent to thatof a plain round bar having the same mass per metre weight per foot asthe deformed bar. Coating mass weight shown i

17、n is based on an assumedarea ratio of 1.2:1 (actual to nominal surface area of the steel reinforcingbar).4.2.2 Magnetic Thickness MeasurementsThe massweight of the coating shall be determined by magneticthickness gage measurements in accordance with PracticeE 376. The thickness measurement is used t

18、o calculate themass weight by multiplying it by the surface area of coatedbar and by the zinc density. One or more of the followingmethods shall be permitted to be used to referee the resultsobtained by magnetic thickness measurements.4.2.2.1 Stripping MethodThe mass weight shall be de-termined by s

19、tripping the coating from the steel reinforcing barsection in accordance with Test Method A 90/A 90M.NOTE 4This is a destructive test appropriate for small samples of aminimum of 2000 mm23 in.2 of surface area. It does note include themass weight of iron reacted with the zinc coating and may overest

20、imatecoating mass weight by up to 10 %.4.2.2.2 Weighing Before and After GalvanizingThe massweight shall be determined by weighing steel reinforcing barsbefore and after galvanizing. The difference between the twomeasurements divided by the surface area of the bars providesthe mass weight. The origi

21、nal weighing shall occur afterpickling and drying. The second weighing shall occur aftercooling to ambient temperature.4.2.2.3 MicroscopyThe mass weight shall be deter-mined by cross-sectional and optical measurement in accor-dance with Test Method B 487. A cross-section sample of thesteel shall be

22、polished and examined with an optical micro-scope to determine the coating thickness. The coating massweight shall be determined by multiplying coating thicknessby the surface area of the coated sample and by the density ofzinc.4.2.3 Number of TestsFor determination of the coatingmass weight, three

23、random samples shall be tested from eachlot. For each magnetic thickness measurement sample, five ormore measurements shall be made at various points throughoutthe sample so as to represent the entire surface of the sample.A total of at least fifteen measurements shall be averaged toobtain the coati

24、ng thickness. For the microscopy method, fivesamples shall be tested per lot. Each sample shall be measuredon four sides and the total of twenty measurements shall beaveraged to obtain the coating thickness. For the strippingmethod and the weighing method, three samples per lot shallbe measured.NOTE

25、 5A lot shall be as follows: All bars of one size furnished to thesame steel reinforcing bar specification that have been galvanized withina single production shift.4.2.4 RetestsIf the average zinc coating mass weightfails to meet the requirements of Table 1, six additional randomsamples from the lo

26、t shall be permitted to be tested. If theaverage zinc coating mass weight of the six samples con-forms to the requirements of Table 1, the lot shall be accepted.4.3 ChromatingThe galvanized coating shall be chromatetreated. This is to preclude a reaction between the bars andfresh portland cement pas

27、te. Proprietary chromating solutionsof equivalent strength are permitted in place of the genericchemical treatment specified.4.3.1 If the chromate treatment is performed immediatelyafter galvanizing, it may be accomplished by quenching thesteel reinforcing bars in a solution containing at least 0.2

28、massweight % of sodium dichromate in water (such as 2kg/m33oz of each 10 gal of quench water) or by quench chromatingin a minimum of 0.2 % chromic acid solution. The solutionshall be at least 32C 90F. The galvanized reinforcing barsshall be immersed in the solution for at least 20 s.4.3.2 If the gal

29、vanized reinforcing bars are at ambienttemperature, the chromate treatment shall be the same asspecified in except that 0.5 to 1.0 % concentration of sulfuricacid shall be added as an activator of the chromate solution. Inthis case, there is no temperature requirement for the activatedchromate solut

30、ion.5. General Requirements5.1 The steel reinforcing bars shall conform to one of thefollowing specifications: A 615M, A 706M, or A 996M A 615,A 706, or A 996.5.2 The zinc used for coating shall be any grade thatconforms to Specification B6.6. Finish and Adherence of Coating6.1 The zinc coating shal

31、l have no bare spots. The coatingshall be free of blisters, flux spots or inclusions, dross, and acidor black spots. Bars that stick together after galvanizing shallbe rejected. In addition, the presence of tears or sharp spikeswhich make the bar hazardous to handle shall be cause forrejection. A ma

32、tte gray finish appearance shall not be itself acause for rejection.NOTE 6Specific concentrations of elements such as silicon, carbon,and phosphorus in steel tend to accelerate the growth of the zinc-iron alloylayer so that the galvanized coating may have a matte finish with little orno free zinc ou

33、ter layer. The mass, shape, and amount of cold working ofthe bar being galvanized may also affect this condition.6.2 The coating shall be adherent so it cannot be removedby any reasonable process of handling or erection.TABLE 1 Mass Weight of Zinc CoatingCoating ClassMass Weight of ZincCoating,min,

34、g/m2oz/ft2 of SurfaceClass IBar Designation Size No. 10 3 915 3.00Bar Designation Size No. 13 4 and Larger 1070 3.50Class IIBar Designation Size No. 10 3 and Larger 610 2.00A 767/A 767M 0927. Fabrication7.1 Before Galvanizing:7.1.1 Steel reinforcing bars that are bent cold prior togalvanizing shall

35、be fabricated to a bend diameter equal to orgreater than those specified in Table 2.7.1.2 Steel reinforcing bars shall be permitted to be coldbent to tighter diameters than specified in (limited to the extentthat the appropriate reinforcing bar specification allows) ifstress relieved at a temperatur

36、e from 480 to 560C 900 to1050F for 1 h per 25 mm 1 in. of bar diameter.7.2 After Galvanizing:7.2.1 When galvanizing is performed before bending, somecracking and flaking of the galvanized coating in the area of thebend shall not be cause for rejection (Note 7).7.2.2 Damage to the coating as a result

37、 of fabrication shallbe repaired in accordance with Section 9.NOTE 7The tendency for cracking of the zinc coating increases withbar diameter and with severity and rate of bending.8. Inspection8.1 The inspector representing the purchaser shall haveaccess at all times, while work on the contract of th

38、e purchaseris being performed, to those areas of the galvanizers plantwhich concern the manufacture of the material ordered. Thegalvanizer shall afford the inspector all reasonable facilities tosatisfy him that the coating is being furnished in accordancewith this specification.8.2 The material shal

39、l be inspected at the galvanizers plantprior to shipment. However, if specified, the purchaser shallmake the tests which govern the acceptance or rejection of thematerials in his own laboratory or elsewhere.8.3 Visual inspection of materials ready for shipment shallbe made to determine conformity wi

40、th the requirements of 6.1.For materials that fail inspection, it shall be permissible for thematerials to be stripped and regalvanized and resubmitted forinspection. They shall conform to the requirements of thisspecification.9. Permissible Amount of Damaged Coating and Repairof Damaged Coating9.1

41、The maximum amount of repaired damaged coatingshall not exceed 1 % of the total surface area in each 0.3-m1-ft length of the bar. This limit on repaired damaged coatingshall not include sheared or cut ends that are repaired with azinc-rich formulation in accordance with Practice A 780/A 780M (see 9.

42、3).9.2 All damaged coating due to fabrication and handling, tothe point of shipment to the job-site, shall be repaired with azinc-rich formulation in accordance with Practice A 780/A 780M.9.3 When coated bars are sheared, saw-cut, or cut by othermeans during the fabrication process, the cut ends sha

43、ll becoated with a zinc-rich formulation in accordance with PracticeA 780/A 780M.10. Certification10.1 Upon request of the purchaser in the contract or order,the galvanizers certification that the material was manufac-tured and tested in accordance with this specification, togetherwith the report of

44、 the tests results, shall be furnished at the timeof shipment.10.2 When Specification A 615/A 615M steel is supplied, asilicon analysis shall be provided.10.3 A material test report, certificate of inspection, orsimilar document printed from or used in electronic form froman electronic data intercha

45、nge (EDI) transmission shall beregarded as having the same validity as a counterpart printed inthe certifiers facility. The content of the EDI transmitteddocument must meet the requirements of the invoked ASTMstandard(s) and conform to any existing EDI agreement be-tween the purchaser and the suppli

46、er. Notwithstanding theabsence of a signature, the organization submitting the EDItransmission is responsible for the content of the report.NOTE 8The industry definition as invoked here is: EDI is thecomputer-to-computer exchange of business information in a standardformat such as ANSI ASC X12.11. K

47、eywords11.1 corrosion resistance; galvanizing; steel reinforcingbars; zinc-coatedTABLE 2 Minimum Finished Bend DiametersBar No. Grade 28040Grade 35050Grade 42060Grade 5207510,13,16 3,4,5 6dA6d 6d .19 6 6d 6d 6d 6d22,25 7,8 6d 8d 8d 8d29,32 9,10 . . . . . . 8d 8d3611 . . 8d 8d43,57 14,18 . . . . . .

48、10d 10dAd = nominal diameter of the bar.A 767/A 767M 093APPENDIXES(Nonmandatory Information)X1. GUIDELINES FOR JOB-SITE PRACTICESX1.1 Specification A 767/A 767M is a product standard.Requirements for zinc-coated (galvanized) steel reinforcingbars from the point of shipment to the job-site and subseq

49、uentpractices at the job-site are not delineated in this productstandard.X1.2 The American Concrete Institute promulgates “Speci-fications for Structural Concrete ACI 301.” SpecificationsACI 301 is intended to be used in its entirety in the projectspecifications. An architect-engineer may cite Standard Speci-fications ACI 301 in the project specifications for any cast-in-place concrete construction project. Standard SpecificationsACI 301 include provisi