ASTM A779/A779M-00
(Specification)Standard Specification for Steel Strand, Seven-Wire, Uncoated, Compacted, Stress-Relieved for Prestressed Concrete
Standard Specification for Steel Strand, Seven-Wire, Uncoated, Compacted, Stress-Relieved for Prestressed Concrete
SCOPE
1.1 This specification describes three grades of compacted, seven-wire, uncoated, stress-relieved strand for use in prestressed concrete construction.
1.2 Supplement I describes low-relaxation strand and low-relaxation testing.
1.3 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only.
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Designation: A 779/A 779M – 00
Standard Specification for
Steel Strand, Seven-Wire, Uncoated, Compacted, Stress-
Relieved for Prestressed Concrete
This standard is issued under the fixed designationA779/A779M; the number immediately following the designation indicates the year
of original 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3.1.3 lot—all of the compacted strand of the same grade and
package size produced on the same production equipment and
1.1 This specification describes three grades of compacted,
submitted for inspection at the same time.
seven-wire, uncoated, stress-relieved strand for use in pre-
tensioned and post-tensioned prestressed concrete construc-
4. Classification
tion.
4.1 Grade 1700 (245)—Nominal diameter of 18.0 mm (0.7
1.2 Supplement I describes low-relaxation strand and low-
in.) with tensile failure stress of 1705 MPa (247 ksi) based on
relaxation testing.
nominal area of the strand.
1.3 The values stated in either inch-pound or SI units are to
4.2 Grade 1800 (260)—Nominal diameter of 15.2 mm (0.6
be regarded as standard. Within the text, the inch-pound units
in.) with tensile failure stress of 1815 MPa (263 ksi) based on
are shown in parentheses. The values stated in each system are
nominal area of the strand.
not exact equivalents; therefore, each system shall be used
4.3 Grade 1860 (270)—Nominal diameter of 12.7 mm (0.5
independently of the other, without combining values in any
in.) with tensile failure stress of 1860 MPa (270 ksi) based on
way.
nominal area of the strand.
2. Referenced Documents
5. Ordering Information
2.1 ASTM Standards:
5.1 Orders for compacted stress relieved strand should
A 370 Test Methods and Definitions for MechanicalTesting
2 include the following information:
of Steel Products
5.1.1 Quantity (meters (feet)),
A 751 Test Methods, Practices, and Terminology for
2 5.1.2 Grade of strand (Section 4),
Chemical Analysis of Steel Products
5.1.3 Special inspection requirements, if desired (see Sec-
E 328 MethodsforStressRelaxationTestsforMaterialsand
3 tion 13),
Structures
5.1.4 Packaging,
3. Terminology 5.1.5 ASTM designation and date of issue, and
5.1.6 Special requirements, if any.
3.1 Definitions of Terms Specific to This Standard:
3.1.1 strand—a group of wires having a center wire en-
NOTE 1—Atypical ordering description is as follows: 100 000 m Grade
closed tightly by six helically placed outer wires with a
260 compacted low-relaxation strand in approximately 3700 m reelless
packs to ASTM A 779/A 779M (328 000 ft Grade 1800 compacted
uniform pitch of not less than 14 and not more than 18 times
low-relaxation strand in approximately 12 000 ft-reelless packs to ASTM
the nominal diameter of the strand.
A 779/A 779M.)
3.1.2 compacted strand—strandthathasbeencompactedby
drawing through a die or a similar compacting process and
6. Materials and Manufacture
subsequently stress-relieved prior to winding into coils or
6.1 The steel shall be of such quality that, when processed,
reelless packs.
the finished wire shall be free of detrimental flaws and undue
segregation.
1 6.2 Wire from which the strand is to be fabricated shall be
This specification is under the jurisdiction of ASTM Committee A-1 on Steel,
in the cold-drawn condition and have a common dry-drawn
Stainless Steel, and RelatedAlloys and is the direct responsibility of Subcommittee
A01.05 on Steel Reinforcement.
finish.
Current edition approved Jan. 10, 2000. Published March 2000. Originally
6.3 After stranding and compacting, all strand shall be
published as A 779 – 80. Last previous edition A 779 – 98.
subjected to a stress-relieving continuous thermal treatment to
Annual Book of ASTM Standards, Vol 01.03.
Annual Book of ASTM Standards, Vol 03.01. produce the desired mechanical properties. Temper colors
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
A 779/A 779M – 00
TABLE 2 Yield Strength Requirements
which result from the stress-relieving operation are considered
normal for the finished appearance of this strand.
Nominal Strand Diameter Initial Load, Specified Minimum
kN (lbf) Load at 1 %
7. Chemical Requirements
mm (in.)
Extension, kN (lbf)
7.1 The chemical analysis of each heat shall be determined
Grade 1860 (270)
in accordance with Test Methods, Practices, and Definitions
12.7 (0.5) 20.9 (4700) 182 (40 900)
Grade 1800 (260)
A 751.
15.2 (0.6) 30.0 (6740) 261 (58 700)
7.2 Variations in production processes and equipment ne-
Grade 1700 (245)
cessitates the individual selection of an appropriate chemical
18.0 (0.7) 38.0 (8540) 330 (74 300)
composition at the discretion of the producer.
7.3 Phosphorus and sulfur values shall not exceed the
following:
10. Workmanship
Phosphorus 0.040 % max
10.1 Joints:
Sulfur 0.050 % max
10.1.1 Thereshallbenostrandjointsorstrandsplicesinany
8. Mechanical Requirements length of the completed strand.
10.1.2 During the process of manufacture of individual
8.1 Breaking Strength—The breaking strength of the fin-
wires for stranding, welding is permitted only prior to the start
ished strand shall conform to the values specified in Table 1
of wire drawing.
and shall be determined using methods and procedures de-
10.2 The finished compacted strand shall be uniform in
scribed in Annex A 7 of Test Methods and Definitions A 370.
diameter and shall be free of imperfections not consistent with
8.2 Load at 1 % Extension—The minimum load at 1 %
good commercial drawing and stranding practice.
extension shall conform to the specified values shown in Table
10.3 When the strand is cut without seizings, the wires shall
2 when tested using methods and procedures described in
not fly out of position. If a wire or wires flies out of position
Annex A 7 of Test Methods and Definitions A 370.
and can be replaced by hand, the strand will be considered
8.3 Elongation—The total elongation of the strand under
satisfactory.
maximum load shall not be less than 3.5 % measured in a gage
10.4 The strand shall not be oiled or greased. Slight rusting,
length of not less than 600 mm (24 in.) when tested using
provided it is not sufficient to cause pits visible to the unaided
methods and procedures described in Annex A 7 of Test
eye, shall not be cause for rejection.
Methods and Definitions A 370.
10.5 Curvature of the finished compact strand shall be not
8.3.1 Strand specimens that break outside of the extensom-
more than 75 mm (3 in.) in a length of1m(3ft) when lying
eter or in the testing machine grips and meet the minimum
on a flat surface.
specified value, are considered as meeting the elongation
requirements of this specification.
11. Sampling
8.4 If any strand specimen breaking within the grips of the
11.1 One specimen for test shall be taken from each 18 Mg
testing machine results in test values below those specified,
(20 ton) or fraction thereof from the lot of compacted strand.
those results shall be considered invalid and ret
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