The National Academies Press

Currently Skimming:

Pages 20-34

The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.

From page 20... ... • Products are formulated with different melting points. Twenty or more different sodium soaps are available, as well as different sources of fatty acid, such as stearic acid. Read the entire page →
From page 21... ... Mechanical Testing As mentioned, the transfer length test is considered the most realistic measure of bond performance and was used as 21 Read the entire page →
From page 22... ... Chemical and Surface Testing Transfer length was not measured on the historic strand and only partial transfer length test results were available for the OSU strand. Consequently, the evaluation of the effectiveness of the chemical and surface QC test methods in predicting bond performance was determined by comparing the QC test results against performance measured in pull-out tests. Read the entire page →
From page 23... ... • Contact angle -- Contact angle correlated with bond only after the strand sample was subjected to exposure to a saturated calcium hydroxide solution. This correlation is higher for those sources judged to carry only stearate-based lubricants, when performance assessed with mortar pull-out is considered. Read the entire page →
From page 24... ... , • Contact Angle Measurement after Lime Dip, • Change in Corrosion Potential, and • Organic Residue Extraction with FTIR Analysis. Read the entire page →
From page 25... ... Despite the somewhat limited scope of the development process used to establish these NASPA test thresholds, the threshold determination effort for the surface and chemical testing conducted in this study was performed assuming that these thresholds were well-defined lower bounds for good bonding behavior. As has been done throughout this study, the thresholds were converted to bond stresses calculated as the force divided by the nominal surface area to support comparisons among all of the tested strands. Read the entire page →
From page 26... ... Contact Angle Measurement after Lime Dip -- The prediction interval for Contact Angle after Lime Dip with a one-sided confidence level of 90% is shown in Figure 5. As can be seen in this figure, this prediction interval exceeds 0.313 ksi when the contact angle is less than 73°. Read the entire page →
From page 27... ... , were as follows: • Contact Angle Measurement after Lime Dip & Change in Corrosion Potential, • Contact Angle Measurement after Lime Dip & Organic Residue Extraction (100% stearate only) , and • Weight Loss on Ignition (LOI) Read the entire page →
From page 28... ... The regression indicated that the last combination of predictors listed above (Contact Angle Measurement after Lime Dip & Organic Residue Extraction) was a good predictor of bond and was performed based only on those strand sources that the FTIR analysis of the organic residue identified as being stearate only. Read the entire page →
From page 29... ... Evaluation of prediction interval for model based on Contact Angle Measurement after Lime Dip & Change in Corrosion Potential. Read the entire page →
From page 30... ... 153 Ca, Zn, P zinc phosphate calcium salt of fatty acid KSU-H Na, K, B borax Na/K stearate 0.209 SC-F Ca, Zn zinc phosphate calcium stearate 0.223 101 Na, K, B borax Na/K stearate 0.241 KSU-F Na, K, B borax Na/K stearate 0.241 102 Na, Ca, B borax Na/Ca stearate 0.441 SC-H Na, K, Zn zinc phosphate sodium stearate 0.472 151 Na, B borax calcium stearate 0.541 SC-IS Na, Zn zinc phosphate sodium salt of fatty acid 0.682 103 Na, Zn zinc phosphate sodium salt of fatty acid 0.944 Table 13. Compounds likely used in manufacture of each source -- historic and recently manufactured strands. Read the entire page →
From page 31... ... Although pull-out testing from concrete appears to correlate best with transfer length, the most reliable and realistic measure of bond performance, the Correlation Round of this test program had to be based on available mortar pull-out results provided from the NCHRP 12-60 Program. The following four test methods showed the best correlation with pull-out bond and are recommended for inclusion in future QC programs: • Weight LOI (QC-I) Read the entire page →
From page 32... ... The following three combinations showed the best correlation, based on the adjusted coefficient of determination (R2 adj.) : • Weight LOI & Contact Angle Measurement after Lime Dip & Change in Corrosion Potential, • Contact Angle Measurement after Lime Dip & Change in Corrosion Potential, and • Contact Angle Measurement after Lime Dip & Organic Residue Extraction (for stearate based residues) Read the entire page →
From page 33... ... This is done by calculating the prediction intervals for singleand multiple-predictor regressions and for determining the threshold on the QC test that corresponds to a predefined threshold using the mechanical test method. This tool is designed to: (1) Read the entire page →
From page 34... ... or fails (lower bound on prediction interval below threshold) Read the entire page →

From page 20...

... • Products are formulated with different melting points. Twenty or more different sodium soaps are available, as well as different sources of fatty acid, such as stearic acid.