ASTM standard quantifies prestressing strand bond performance

Source: ASTM International, West Conshohocken, Pa.

ASTM A1081/A1081M, Test Method for Evaluating Bond of Seven-Wire Steel Prestressing Strand is the first repeatable and reproducible process aimed at PC strand, which has been used for more than a century in construction applications.

Bonding issues in the pre-tensioned segment of the prestressed concrete made evident the need for the test ASTM A1081/A1081M describes. “Prestressing concrete is a vital construction technology used throughout the world,” says Insteel Wire Products Metallurgist Christopher Reeve, a member of ASTM International Committee A01 on Steel, Stainless Steel and Related Alloys. “PC strand producers need the test covered in ASTM A1081/A1081M to be able to evaluate the bond characteristics of their product as a quality control/quality assurance check point in manufacturing.” Users, he adds, need such a test to be able to qualify potential PC strand suppliers and monitor existing suppliers.

Prestressing concrete technology most commonly uses seven-wire steel strands, as described in ASTM A416/A416M, Specification for Steel Strand, Uncoated Seven-Wire for Prestressed Concrete. PC strands impart compressive force to structural members, enabling otherwise brittle concrete 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.

ASTM A416/A416M was developed by Subcommittee A01.05 on Steel Reinforcement. Due to the limited number of facilities available to perform the test, A01.05 is interested in identifying laboratories that are willing to perform it and remains open to participants in standards developing activities. Contacts: Christopher Reeve, Insteel Wire, 615/451-6330, ext. 2762, [email protected]; ASTM staff liaison, Kevin Shanahan, 610/832-9737, [email protected]; and, standards ordering, ASTM Customer Relations, 877/909-ASTM,  [email protected].