1、Designation: A779/A779M 10A779/A779M 12Standard Specification forSteel Strand, Seven-Wire, Uncoated, Compacted, Stress-Relieved Compacted for Prestressed Concrete1This standard is issued under the fixed designation A779/A779M; the number immediately following the designation indicates the yearof ori
2、ginal adoption or, in the case of revision, the 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.1. Scope*1.1 This specification describes covers two types and three grade
3、s of compacted, seven-wire, uncoated, stress-relieved uncoatedstrand for use in pre-tensioned and post-tensioned prestressed concrete construction. The two types of strand are low-relaxationand stress-relieved (normal-relaxation). The three grades are 245 1700, 260 1800 and 270 1860.1.2 Supplement I
4、 describes low-relaxation strand and low-relaxation testing. This specification is applicable for orders in eitherinch-pound units (as Specification A779) or in SI units (as Specification A779M).1.3 The values stated in either inch-pound or SI units are to be regarded as standard. Within the text, t
5、he inch-poundSI unitsare shown in parentheses.brackets. The values stated in each system aremay not be exact equivalents; therefore, each system shallbe used independently of the other, without combining values in any way.other. Combining values from the two systems may resultin non-conformance with
6、 the specification.2. Referenced Documents2.1 ASTM Standards:2A751 Test Methods, Practices, and Terminology for Chemical Analysis of Steel ProductsA994 Guide for Editorial Procedures and Form of Product Specifications for Steel, Stainless Steel, and Related AlloysA1061/A1061M Test Methods for Testin
7、g Multi-Wire Steel Strand2.2 U.S. Military Standard3MIL-STD-129 Marking for Shipment and Storage2.3 U.S. Federal Standard3Fed. Std. No. 123 Marking for Shipments (Civil Agencies)3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 compacted strandstrand that has been compacted by d
8、rawing through a die or a similar compacting process andsubsequently stress-relieved prior to winding into coilsreels or reelless packs.3.1.2 lotall of the compacted strand of the same grade and package size in the reels or reelless packs produced on the sameproduction equipment and submitted for in
9、spection at the same time.3.1.3 stranda group of wires having a center wire enclosed tightly by six helically placed outer wires with a uniform pitchof not less than 14 and not more than 18 times the nominal diameter of the strand.4. Classification4.1 Grade 1700 (245)245 1700Nominal diameter of 18.0
10、 mm (0.7 in.)0.7 in. 18.0 mm with tensile failure stress of 1705MPa (247 ksi)strength of 247 ksi 1705 MPa based on nominal area of the strand.1 This specification is under the jurisdiction ofASTM Committee A01 on Steel, Stainless Steel and RelatedAlloys and is the direct responsibility of Subcommitt
11、ee A01.05on Steel Reinforcement.Current edition approved April 1, 2010Sept. 1, 2012. Published July 2010October 2012. Originally approved in 1980. Last previous edition approved in 20052010 asA779/A779M 05.A779/A779M 10. DOI: 10.1520/A0779_A0779M-10.10.1520/A0779_A0779M-12.2 For referencedASTM stand
12、ards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 Available from Standardization Documents Order Desk, DODSSP, Bldg. 4, Section D, 700
13、Robbins Ave., Philadelphia, PA 19111-5098, http:/dodssp.daps.dla.mil.This 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
14、 all changes accurately, ASTM recommends that users consult prior editions 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
15、, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14.2 Grade 1800 (260)260 1800Nominal diameter of 15.2 mm (0.6 in.)0.6 in. 15.2 mm with tensile failure stress of 1815MPa (263 ksi)strength of 263 ksi 1815 MPa based on nominal area of the strand.4.3 Grade 1860 (270)
16、270 1860Nominal diameter of 12.7 mm (0.5 in.)0.5 in. 12.7 mm with tensile failure stress of 1860MPa (270 ksi)strength of 270 ksi 1860 MPa based on nominal area of the strand.5. Ordering Information5.1 It shall be the responsibility of the purchaser to specify all requirements that are necessary for
17、material ordered to thisspecification. Such requirements shall to be considered include, but are not limited to, the following:5.1.1 Quantity (meters (feet),(feet metres),5.1.2 Type of strand (low-relaxation or stress-relieved (normal-relaxation),5.1.3 Grade and nominal diameter of strand (Section 4
18、4),),5.1.4 Special inspection requirements, Load-elongation curve, if desired (see (12.2.1Section 13),),5.1.5 Packaging, Outside inspection, if required (Section 13),5.1.6 Packaging (16.1), and5.1.7 ASTM designation and date of issue, and issue.5.1.6 Special requirements, if any.NOTE 1A typical orde
19、ring description is as follows: 100 000 m Grade 260 compacted low-relaxation strand in approximately 3700 m reelless packsto ASTM A779/A779M (328 000 ft Grade 1800 compacted low-relaxation strand in approximately 12 000 ft-reelless packs to ASTM A779/A779M.)6. Materials and Manufacture6.1 The steel
20、shall be of such quality that, when processed, the finished wire shall be free of detrimental flaws and unduesegregation.6.2 Wire from which the strand is to be fabricated shall be in the cold-drawn condition and have a common dry-drawn finish.6.3 After stranding and compacting, all low-relaxation s
21、trand shall be subjected to a stress-relieving continuous thermalthermal-mechanical treatment to produce the desired mechanical properties. prescribed mechanical properties. For stress-relieved(normal-relaxation) strand, only thermal treatment is necessary. Temper colors which result from the stress
22、-relieving operation areconsidered normal for the finished appearance of this strand.7. Chemical Requirements7.1 The chemical analysis of each heat shall be determined in accordance with Test Methods, Practices, and DefinitionsTer-minology A751.7.2 Variations in production processes and equipment ne
23、cessitatesnecessitate the individual selection of an appropriate chemicalcomposition at the discretion of the producer.manufacturer.7.3 Phosphorus and sulfur values shall not exceed the following:Phosphorus 0.040 % maxSulfur 0.050 % max8. Mechanical Properties Property Requirements8.1 Tests for mech
24、anical properties shall be conducted in accordance with Test Methods A1061/A1061M.8.2 Breaking StrengthThe breaking strength of the finished strand shall conform to the values specified in Table 1.8.3 Load at 1 % ExtensionYield StrengthYield strength in pounds kN shall be measured at 1 % extension u
25、nder load. Theminimum load at 1 %1 % extension shall conform to the specified values shown in Table 2. Initial loads are listed in Table 2.8.3.1 The extension under load shall be measured by an extensometer calibrated with the smallest division not larger than0.0001 in. /in. 0.0001 mm/mm of gage len
26、gth.8.4 ElongationThe total elongation of the strand under maximum load shall not be less than 3.5 % measured in 3.5 % usinga gage length of not less than 600 mm (24 in.). 24 in. 600 mm. It shall be permissible to determine the total elongation valueby adding, to the 1.0 % yield extension, the perce
27、nt extension or movement between the jaws gripping the strand after yielddetermination. The percent is calculated on the new base length of jaw-to-jaw distance.8.4.1 Strand specimens that break outside of the extensometer or in the testing machine grips and meet the minimum specifiedvalue, shall be
28、considered as meeting the elongation requirements of this specification.8.5 Relaxation PropertiesIf any strand specimen breaking within the grips of the testing machine results in test values belowthose specified, those results shall be considered invalid and retesting shall be required. Low-relaxat
29、ion strand shall have relaxationlosses of not more than 2.5 % when initially loaded to 70 % of specified minimum breaking strength after 1000 hours of testing.8.5.1 If required, relaxation evidence shall be provided from the maufacturers records of tests on similarly dimensioned strandof the same gr
30、ade.A779/A779M 1229. Dimensions and Permissible Variations9.1 The size of the finished strand shall be expressed as the nominal diameter of the strand in fractions or decimal fractions ofan inch. inches millimetres.9.2 Prior to compacting, the diameter of the center wire of any strand shall be large
31、r than the diameter of any outer wire by aminimum of 2 %.9.3 After compacting, the strand shall conform to a size tolerance of plus 0.4 mm (0.016 in.) or minus 0.2 mm (0.008 in.)0.016in. 0.4 mm or minus 0.008 in. 0.2 mm from the nominal diameter when measured across the crowns of the wire.10. Workma
32、nship10.1 Joints:10.1.1 There shall be no strand joints or strand splices in any length of the completed strand.TABLE 1 Breaking Strength RequirementsNominal Diameter of Strand Specified MinimumBreaking Strengthof Strand, kN (lbf)Nominal Steel Area of Strand Nominal Mass (Weight) ofStrands kg/1000 m
33、 (lb/1000 ft)mm (in.) mm2 (in.)2Grade 1860 (270)12.7 (0.5) 209 (47 000) 112 (0.174) 890 (600)Grade 1800 (260)15.2 (0.6) 300 (67 440) 165 (0.256) 1295 (873)Grade 1700 (245)18.0 (0.7) 380 (85 430) 223 (0.346) 1750 (1176)TABLE 1 Breaking Strength RequirementsNominal Diameter of Strand Specified Minimum
34、Breaking Strengthof Strand, lbf kNNominal Steel Area of Strand Nominal Mass (Weight) ofStrands lb/1000 ft kg/1000 min. mm in.2 mm2Grade 270 18600.5 12.7 47 000 209 0.174 112 600 890Grade 260 1800(0.6 15.2 67 440 300 0.256 165 873 1295Grade 245 17000.7 18.0 85 430 380 0.346 223 1176 1750TABLE 2 Yield
35、 Strength RequirementsNominal Strand Diameter Initial Load,kN (lbf)Specified MinimumLoad at 1 %Extension, kN (lbf)mm (in.)Grade 1860 (270)12.7 (0.5) 20.9 (4700) 182 (40 900)Grade 1800 (260)15.2 (0.6) 30.0 (6740) 261 (58 700)Grade 1700 (245)18.0 (0.7) 38.0 (8540) 330 (74 300)TABLE 2 Yield Strength Re
36、quirementsNominal Strand Diameter Initial Load,lbf kNSpecified MinimumLoad at 1 %Extension, lbf kNin. mm Normal-Relaxation Low-RelaxationGrade 270 18600.5 12.7 4700 20.9 40 900 182 42 300 188Grade 260 18000.6 15.2 6740 30.0 58 700 261 60 700 270Grade 245 17000.7 18.0 8540 38.0 74 300 330 76 900 342A
37、779/A779M 12310.1.2 During the process of manufacture of individual wires for stranding, welding shall be permitted only prior to the startof wire drawing.10.2 The finished compacted strand shall be uniform in diameter and shall be free of imperfections not consistent with goodcommercial drawing and
38、 stranding practice. imperfections.10.3 When the strand is cut without seizings, the wires shall not fly out of position. If a wire or wires flies out of position andcan be replaced by hand, the strand will be considered satisfactory.10.4 The strand shall not be oiled or greased. Slight rusting, pro
39、vided it is not sufficient to cause pits visible to the unaided eye,a person with normal or corrected vision, shall not be cause for rejection.10.5 Curvature of the finished compact strand shall be not more than 75 mm (3 in.)3 in. 75 mm in a length of 1 m (3 ft)3 ft1 m when lying on a flat surface.1
40、1. Sampling11.1 One specimen for test shall be taken from each 18 Mg (20 ton) or fraction thereof from the lot of compacted strand. Thetest specimen shall be cut from the outside ends Test specimens cut from either end of reels or either end of coils or reelless packs.reelless packs are permitted.12
41、. Test Methods Number of Tests12.1 Test specimens obtained in 11.1 shall be tested for dimensions (SectionOne test specimen shall be taken from each 20-ton9), breaking strength (18-t production lot of8.2), load at 1 % extension ( finished strand, and tested for8.3), elongation ( breakingstrength,8.4
42、), and workmanship (Section yield strength, and elongation.10).12.2 Typical load-elongation curves, based on accumulated data, shall be delivered to the purchaser on each lot shipped.12.2.1 When specified in the purchase order or contract, a load-elongation curve shall be made from one test specimen
43、representing the lot.13. Inspection13.1 Inspection of the material shall be agreed upon by the purchaser and the supplier as part of the purchase contract.13.1 If purchaseroutside inspection is required, the suppliermanufacturer shall afford the inspector representing the purchaserall reasonable fac
44、ilities so that the inspector is satisfied reasonable access to the facilities, which concern the manufacture of thematerial ordered, to satisfy the inspector that the material being furnished is in accordance with this specification. All tests andinspections shall be made at the place of manufactur
45、e prior to shipment, and shall be so conducted as not to interfere unnecessarilywith the operation of the works. manufacturers operations.14. Rejection and Rehearing14.1 Failure of any test specimen to comply with the requirements of the specification shall constitute grounds for rejection ofthe lot
46、 represented by the specimen.14.2 The lot shall be resubmitted for inspection by testing a specimen from each reel or reelless pack and sorting outnon-conforming material.14.3 Material that fails to conform to the requirements of this specification shall be subject to rejection. Rejection shall bere
47、ported to the producer or supplier promptly and in writing. In case of dissatisfaction with the test results, the producer or suppliershall have the right to make claim for a rehearing. If there is a reasonable doubt in the initial testing as to the ability of the strandto meet any requirement of th
48、is specification, two additional tests shall be made on specimens of strand from the same reel orreelless pack, and if failure occurs in either of these tests, the strand shall be rejected.15. Certification15.1 If inspection by the purchaser is waived, outside inspection is not required, a manufactu
49、rers certification that the materialhas been tested in accordance with, and meets the requirements of this specification, shall be the basis of acceptance of the material.The certification shall include the specification number, year-date of issue, and revision letter, if any.15.2 A material test report, certificate of inspection, or similar document printed from or used in electronic form from anelectronic data interchange (EDI) transmissi
