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9 CHAPTER 2 Research Approach Overview Industry Survey The work plan developed to achieve these objectives was Letters and accompanying questionnaires were sent out to divided into the following three phases. obtain additional information about strand production. One The initial phase involved gathering information about letter was sent to strand producers and the other was sent to strand manufacturing and potential test methods from the drawing lubricant manufacturers. No one returned the ques- prestressed concrete, strand manufacturing, and wiredrawing tionnaire. Instead, the research team received a few phone lubricant industries, as well as from the available literature. calls, primarily from strand producers who expressed concern Based on this information, a number of chemical and surface that this research would interfere with their business. test methods and performance-based (i.e., mechanical) test Several lubricant producers were cooperative when con- methods that were considered to have potential for use in a tacted by phone. They shared some information about their quality control program were proposed for evaluation. products and their use in strand production. In the second phase of this work, the proposed surface and To facilitate discussion, a meeting was held with members chemical test methods were conducted on a limited number of the project team, NASPA, and Bruce Russell, co-principal of available sources of strand with variable bond properties: investigator of NCHRP Project 12-60: Transfer, Development, (1) to evaluate the ability of these methods to predict bond and Splice Length for Strand/Reinforcement in High-Strength performance and (2) to assess their suitability for routine Concrete, and a consultant to NASPA. This meeting was held quality control operations. In addition, performance-based at WJE's Northbrook, IL, headquarters on 7 January 2004. tests were conducted on some of the same strand sources. The objective of this meeting was to present the strand pro- Those test methods that showed good correlation with bond ducers with an opportunity to give feedback on the proposed performance were selected for further study, while those work plan for this project, which had been provided in that did not were abandoned. A parallel set of investiga- advance for their review, and to provide the project team the tions, termed supplemental investigations, was conducted to opportunity to gain some insight into industry practice and learn more about the relationship between bond and residual the applicability of the proposed testing methods. In addition, lubricants. it was hoped that this meeting would lay the groundwork for In the third and final phase, the promising surface and future interactions regarding this project. chemical test methods were performed on a different group of strand sources to validate their correlation with bond Quality Control performance. At the direction of the supervisory panel, bond Program Development performance was quantified by another researcher using the pre-existing performance-based test procedure. Testing The purpose of a QC program is to assess, by routine mon- was also conducted to support the development of a precision itoring and testing, whether a particular level of quality is statement. Finally, statistical analysis was performed to iden- maintained during production. In this context of strand bond, tify minimum acceptance thresholds for the surface and the desired QC program would evaluate the surface condition chemical test methods that would predict adequate bond of strand so that steps can be taken in a timely manner, if performance as defined by the pre-existing performance-based needed, to ensure that the bond between strand and concrete test procedure. products is reliable and structurally adequate.