Background for the new PCI recommended practice on strand bond

The new PCI “Recommended Practice to Assess and Control Strand/Concrete Bonding Properties of ASTM A416 Prestressing Strand” specifies two new threshold limits for pullout tests conforming to ASTM A416 and new equations for the transfer and development length of prestressing strand. This article provides a summary of more than 30 years of research and knowledge advancement on the bond between concrete and prestressing strand related to the development of the new recommended practice. Discussions regarding the adoption and incorporation of the new recommended practice into structural design, strand production, and precast concrete fabrication and quality control practices are ongoing.