Seven-Wire Steel Prestressing Strand
Prestressing concrete has existed in the construction industry for more than 100 years, but without a repeatable and reproducible test capable of quantifying the bond performance of prestressing steel strands (commonly called PC strand). This test has now been developed in the form of A1081/A1081M, Test Method for Evaluating Bond of Seven-Wire Steel Prestressing Strand.
A1081/A1081M was developed by Subcommittee A01.05 on Steel Reinforcement, part of ASTM International Committee A01 on Steel, Stainless Steel and Related Alloys.
Prestressing concrete technology most commonly uses seven-wire prestressing steel strands, as described in A416/A416M, Specification for Steel Strand, Uncoated Seven-Wire for Prestressed Concrete.
PC strands impart compressive force to concrete structural members, enabling otherwise brittle concrete members to reliably span long distances. When PC strands are tensioned in forms prior to pouring the concrete, the tension in the strands must bond to the concrete sufficiently to cause the concrete member to be in a state of compression once the strands are released from the tensioning anchorages.
Bonding issues in the pre-tensioned segment of the prestressed concrete made evident the need for the bonding test described in A1081/A1081M.
“Prestressing concrete is a vital construction technology used throughout the world,” says Christopher Reeve, a metallurgist with Insteel Wire Products, and a member of Committee A01. “PC strand producers need the test covered in A1081/A1081M to be able to evaluate the bond characteristics of their product as a quality control/quality assurance checkpoint in their manufacturing processes.”
In addition, Reeve notes, PC strand users need such a test to be able to qualify potential PC strand suppliers and monitor existing suppliers.
A01.05 invites interested parties to participate in its standards developing activities. Due to the limited number of facilities currently available to perform the test, A01.05 is particularly interested in identifying laboratories that are willing to perform it.
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CONTACT Technical Information: Christopher F. Reeve, Insteel Wire Products • Gallatin, Tenn. • Phone: 615-451-6330, ext. 2762 | ASTM Staff: Kevin Shanahan • Phone: 610-832-9737 | Upcoming Meeting: May 20-23 • May Committee Week • Indianapolis, Ind.
This article appears in the issue of Standardization News.