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31 lubricants used based on the prominent elements. Knowledge A main objective of this study was to develop test methods about the types of pretreatments and drawing lubricants can that were more easily performed at more frequent intervals be an important part of the interpretation of the QC test than mechanical pull-out tests, which are time consuming, results. especially for a prestressing strand producer. The three rec- These results of the elemental analyses suggest that the ommended Level I QC tests are all easier to conduct than wires in the sampled strands were pretreated using one of two pull-out tests and, although they require some training and methods during the manufacturing process. Those strands that the acquisition of some specialized equipment, could be con- carried high amounts of boron typically carried low amounts ducted by strand producers or precasters. If a QC lab was set of zinc and phosphate. As expected, the lubricants appeared up, it is envisioned that performing all three of these tests on to be either calcium or sodium/potassium stearates, but a a given sample of strand would require less than four hours number of strands showed evidence of both. This may result of an appropriately trained QC inspector's time. If more than from different types of lubricants being used in separate dies one sample is tested, the amount of time required per sample in the drawing process. would be much less since much of the effort would be There is a greater amount of sodium, potassium, and calcium duplicative. Although, as discussed further in the next sec- than would be expected from the stearate compounds alone tion, the definition of thresholds on all four of these tests was (based on the concentration of the organic residues extracted). not straightforward, all of these methods showed a correla- Therefore, other sources of these elements are contributing to tion to bond performance in concrete, mortar, or both and the values measured here. Possible sources include chemicals would have value in a QC program as an indicator of bond in the pretreatment processes described above, detergents quality. used for cleaning, or fillers, such as lime, used in some drawing Recently, strand manufacturers in the United States have lubricants. begun conducting pull-out testing from a single, specially prepared spool of 1/2-in. strand on a quarterly basis. Although this is obviously better than no testing, it currently repre- Interpretation and Applications sents a small portion of the strand produced annually by each Development of Quality Control Program supplier. Therefore, it is suggested that the recommended for Strand Bond Level I QC methods could be conducted by strand producers on a weekly basis for each size of strand produced. As a A number of QC test methods for predicting strand bond frame of reference, a requirement of weekly testing is much performance have been developed and evaluated in this test- less onerous than the QC program requirements for at least ing program. The value of these tests was judged based on the one other reinforcing steel product--during production of correlation observed between these methods and mechanical epoxy-coated reinforcing steel at many manufacturing facil- testing methods. Three pull-out test procedures, differing ities, a number of QC tests, such as checks of blast cleaning mainly by the embedment material, were also examined dur- effectiveness and coating flexibility, are conducted more fre- ing this program. Although pull-out testing from concrete quently than every four hours of production. It is also not un- appears to correlate best with transfer length, the most reli- common for precasters to test concrete properties (including able and realistic measure of bond performance, the Correla- slump, air content, and strength) more frequently than once tion Round of this test program had to be based on available per day. mortar pull-out results provided from the NCHRP 12-60 Regular QC testing should greatly decrease the likelihood Program. that poor bonding strand would reach the market, and this The following four test methods showed the best correla- type of testing would be a valuable supplement to the quarterly tion with pull-out bond and are recommended for inclusion testing of only a single size of strand currently being performed. in future QC programs: When lots of strand are produced that exhibit suspicious behavior identified by these test methods, this could then Weight LOI (QC-I), prompt additional testing using the Level II organic residue Contact Angle Measurement after Lime Dip (QC-I), extraction test and mechanical pull-out testing. Change in Corrosion Potential (QC-I), and It is also noted that routine QC analyses of new batches of Organic Residue Extraction with FTIR Analysis (QC-II). the drawing lubricants are not routinely conducted. Instead, problems with lubricant are generally only noted while the The QC tests have been divided into two categories, de- wiredrawing process is ongoing. Although the development pending on the complexity and time required to conduct the of such a test program was beyond the scope of this research, tests: Level I (QC-I) and Level II (QC-II) tests. The QC level greater QC as part of the lubricant acquisition process also is shown in the bulleted list above. would add to the confidence in bond quality.