ASTM A886/A886M-24

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Designation: A886/A886M − 17 A886/A886M − 24
Standard Specification for
Steel Strand, Low-Relaxation, Indented, Seven-Wire Stress-
Relieved Steel Strand for Prestressed Concrete
This standard is issued under the fixed designation A886/A886M; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope*
1.1 This specification covers two types and two grades of indented seven-wire uncoated, low-relaxation, indented, Grade 270I
[1860I] seven-wire steel strand for use in prestressed concrete construction. The two types of strand are low-relaxation and
stress-relieved (normal-relaxation). Grade 250I [1725I] and Grade 270I [1860I] have minimum tensile strengths of 250 ksi [1725
MPa] and Grade 270I [1860I] has a minimum tensile strength of 270 ksi [1860 MPa], respectively, MPa] based on the nominal
area of the strand.
1.2 The text of this specification references notes and footnotes that provide explanatory material. These notes and footnotes
(excluding those in tables) shall not be considered as requirements of the specification.
1.3 This specification is applicable for orders in either inch-pound units (as Specification A886) or in SI units (as Specification
A886M).
1.4 The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the text, the SI units
are shown in brackets. The values stated in each system aremay not be exact equivalents; therefore, each system shall be used
independently of the other. Combining values from the two systems may result in non-conformance with the specification.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standard:
A1061/A1061M Test Methods for Testing Multi-Wire Steel Prestressing Strand
2.2 U.S. Military Standard:
MIL-STD-129 Marking for Shipment and Storage
2.3 U.S. Federal Standard:
Fed. Std. No. 123 Marking for Shipments (Civil Agencies)
This specification is under the jurisdiction of ASTM Committee A01 on Steel, Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee A01.05
on Steel Reinforcement.
Current edition approved Nov. 1, 2017March 1, 2024. Published November 2017March 2024. Originally approved in 1988. Last previous edition approved in 20162017
as A886/A886M – 16.A886/A886M – 17. DOI: 10.1520/A0886_A0886M-17.10.1520/A0886_A0886M-24.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from U.S. Government Printing Office, Superintendent of Documents, 732 N. Capitol St., NW, Washington, DC 20401-0001, http://www.access.gpo.gov.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
A886/A886M − 24
3. Terminology
3.1 Definition of TermTerms Specific to this Specification:
3.1.1 lay length, n—the axial distance required to make one complete revolution of any outer wire of a strand.
3.1.2 strand, n—a group of wires having a center wire enclosed tightly by six helically placed outer wires with uniform pitch of
not less than 12 and not more than 16 times the nominal diameter of the strand.wires.
3.1.2.1 Discussion—
The direction of lay is either right-handed or left-handed.
3.1.3 strand splice, n—a production connection between two separate lengths of strand never intended to carry prestressing loads.
3.1.4 wire weld, n—a resistance butt-weld joining two separate lengths of wire after wire drawing and before the wire is formed
into strand.
4. Ordering Information
4.1 Orders for indented low-relaxation, indented, Grade 270 seven-wire steel strand under this specification shall contain the
following information:
4.1.1 Quantity (feet [metres]),
4.1.2 Nominal diameter of strand (inches [millimetres]), and
4.1.3 Grade of strand,
4.1.4 Type of strand (low-relaxation or stress-relieved (normal-relaxation)), and
4.1.3 ASTM designation A886 [A886M] and year of issue.
4.2 The purchaser shall have the option to specify additional requirements, including but not limited to, the following:
4.2.1 Relaxation evidence from similarly dimensioned strand of the same grade (6.5.1),
4.2.2 Other types of indented wire (7.4.27.5.2),
4.2.3 If joints or Whether strand splices are permitted (8.1.1),
4.2.4 Weldless, if desired Weldless strand (8.1.48.2.2),
4.2.5 Requirements for outside inspection (11.1),
4.2.6 Load-elongation curve, if desired curve (13.2),
4.2.7 Packaging and package marking (Section 14), and
4.2.8 Other special requirements, if any.
5. Materials and Manufacture
5.1 Base Metal—The base metal shall be carbon steel of such quality that when it is drawn to wire, subjected to the indentation
process, fabricated into strand, and then thermally treated, it shall have the properties and characteristics prescribed in this
specification.
5.2 Wire—The wire from which the strand is to be fabricated shall be round and have a common dry-drawn finish.
5.2.1 Traceability—Traceability shall be based on pack number as reported by the manufacturer.
A886/A886M − 24
TABLE 1 Nominal Dimensions of Indentations
Wire Diameter, d Nominal Diameter Depth, a Length, L Pitch, P
of Strand
Fig.
in. [mm] in. [mm] in. [mm] in. [mm] in. [mm]
1 (a) # 0.104 [# 2.6] 0.312 [7.9] 0.002 to 0.004 [0.05 to 0.10] 0.079 [2.0] 0.220 [5.6]
1 (a) > 0.125 [> 3.2] 0.375 [9.5] 0.002 to 0.005 [0.05 to 0.13] 0.108 [2.7] 0.220 [5.6]
0.438 [11.1]
0.500 [12.7]
1 (b) # 0.125 [# 3.2 ] 0.375 [9.5] 0.002 to 0.006 [0.05 to 0.15] 0.115 [2.9] 0.220 [5.6]
NOTE 1—This product is a composite of seven wires and is produced only to onlymeet the prescribed mechanical properties. The chemical composition
of all wires or any individual wire is not pertinent to this application, and heat identity is not necessarily maintained. It is possible that wire from more
than one heat may be used in the manufacture of a reel or reelless pack. Traceability is based on the identity of reels or reelless packs as maintained and
reported by the manufacturer. pack.
5.3 Indentations—The outer wires shall have indentations that inhibit longitudinal movement of the strand relative to the concrete
surrounding the strand in prestressed concrete construction. Indentations shall conform to the provisions in Section 7.47.5. The
surface of the outer wires shall be suitably deformed mechanically by rolling to produce a series of indentations. Indentations shall
be in two or more lines spaced uniformly around the wire. Indentations in adjacent lines shall be staggered throughout the length
of the wire. At least 90 % of the indentations in any 2 ft [0.6 m] length of strand shall meet the pitch and shape requirements of
Table 1. The center wire need not be indented.
5.4 Treatment—After stranding, low-relaxation strand shall be subjected to a continuous thermal-mechanical treatment to produce
the prescribed mechanical properties. For stress-relieved (normal-relaxation) strand, only thermal treatment is necessary. Temper
colors which result from the stress-relieving operationthermal-mechanical treatment are considered normal for the finished
appearance of this strand.
6. Mechanical Property Requirements
6.1 Tests for mechanical properties shall be conducted in accordance with Test Methods A1061/A1061M.
6.2 Breaking Strength—The breaking strength of the finished strand shall conform to the requirements prescribed in Table 2.
6.3 Yield Strength—Yield strength in lbspounds [kN] shall be measured at 1 %1.0 % extension under load. The minimum yield
strength shall be 90 % for low-relaxation strand and 85 % for stress-relieved (normal-relaxation) strand of the breaking strength
listed in Table 2. Initial loads for the test and minimum yield strengths are listed in Table 3.
6.3.1 The extension under load shall be measured by an extensometer calibrated with the smallest division not larger than 0.0001
in./in. [0.0001 mm/mm] of gage length.
6.4 Elongation—The total elongation under load shall not be less than 3.5 % using a gage length of not less than 24 in. [600 mm].
It shall be permissible to determine the total elongation value by adding, to the 1 % yield extension1.0 % yield extension, the
percent extension or movement between the jaws gripping the strand after yield determination. The percent is calculated on the
new base length of jaw-to-jaw distance.
6.5 Relaxation Properties—Low-relaxation strand Strand shall have relaxation losses of not more than 2.5 % when initially loaded
to 70 % of specified minimum breaking strength or not more than 3.5 % when loaded to 80 % of specified minimum breaking
strength of the strand after 1000 hoursh of testing.
6.5.1 If required, relaxation evidence shall be provided from the manufacturer’s records of tests on similarly dimensioned strand
of the same grade.strand.
7. Dimensions and Permissible Variations
7.1 The size of the finished strand shall be expressed as the nominal diameter of the strand in inches [mm]. All nominal
dimensional requirements for wires and strands shall refer to the wire and strand before indenting.
A886/A886M − 24
TABLE 2 Breaking Strength Requirements
Nomminal Mass [Weight] of
Steel
Diameter of Strand Breaking Strength Strand,
Area of Strand,
of Strand, lbf [kN] lb/1000 ft
2 2
in. [mm]
in. [mm ]
[kg/1000 m]
Grade 250I [1725I]
0.250 [6.4] 9 000 [40.0] 0.036 [23.2] 122 [182]
0.313 [7.9] 14 500 [64.5] 0.058 [37.4] 197 [294]
0.375 [9.5] 20 000 [89.0] 0.080 [51.6] 272 [405]
0.438 [11.1] 27 000 [120.1] 0.108 [69.7] 367 [548]
0.500 [12.7] 36 000 [160.3] 0.144 [92.9] 490 [730]
0.600 [15.2] 54 000 [240.5] 0.216 [139.4] 737 [1094]
Grade 270I [1860I]
0.313 [7.9] 16 500 [74.3] 0.061 [39.4] 210 [313]
0.313 [7.9] 16 500 [74.3] 0.061 [39.4] 210 [313]
0.375 [9.5] 23 000 [101.9] 0.085 [54.8] 290 [432]
0.438 [11.1] 31 000 [138.0] 0.115 [74.2] 390 [582]
0.500 [12.7] 41 300 [183.6] 0.153 [98.7] 520 [775]
0.600 [15.2] 58 600 [260.4] 0.217 [140.0] 740 [1102]
A
TABLE 3 Yield Strength Requirements
Minimum Load
Nominal Initial Load, at 1 %
Diameter of Strand lbf [kN] Extension, kN
[lbf]
B
in. [mm] Stress-Relieved Low Relaxation
(Normal
A
Relaxation)
Grade 1725I [250I]
0.250 [6.4] 900 [4.0] 7 650 [34.0] 8 100 [36.0]
0.313 [7.9] 1 450 [6.5] 12 300 [54.8] 13 050 [58.1]
0.375 [9.5] 2 000 [8.9] 17 000 [75.6] 18 000 [80.1]
0.438 [11.1] 2 700 [12.0] 23 000 [102.3] 24 300 [108.2]
0.500 [12.7] 3 600 [16.0] 30 600 [136.2] 32 400 [144.3]
0.600 [15.2] 5 400 [24.0] 45 900 [204.4] 48 600 [2
...