Click for next page ( 20


The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 19
19 Confined 40 C Confinement, +2% 40 C 20 C 4C -Teflon / +Latex - Milled / +Sawed -Without / +With Membrane Strain, +25 microstrain -Water / +Air Time, min Temperature, +0.5 C -3 -2 -1 0 1 2 3 Change in Phase Uniformity, Degree Figure 11. Effect of statistically significant ruggedness factors on the phase uniformity. data (11). For phase uniformity, temperature, conditioning based on anticipated test variability. The following conclu- fluid, and end condition did not appear to affect the results. sions were drawn for each of the ruggedness factors: Figure 11 shows the effect of the remaining factors on the phase 1. Equilibrium temperature. The current temperature uniformity. The effects are generally small and not consistent control of 0.5C in SPT is acceptable. Temperature changes over the testing conditions, except for the membrane effect. over this level are expected to result in less than a 6 percent Phase angles are more variable in unconfined tests when the change in the dynamic modulus and less than a 0.6 degree membrane is used. change in the phase angle. 2. Transfer time. The transfer time over the range of 2.2.3 Summary 3 to 5 min was not found to be a significant factor in the measured material properties, and had only a minor effect on Table 20 summarizes the results of the analysis of the rugged- the data quality. The transfer time can be increased to 5 min. ness test data for the dynamic modulus test. For statistically significant ruggedness factors, Table 20 presents the effect of 3. Conditioning fluid. The use of water as a condition- the factor on the measured modulus and phase angle and the ing fluid results in significantly poorer quality test data for data quality indicators. Table 20 also presents acceptable values confined test conditions. Air should, therefore, be used as the Table 20. Summary of the effect of ruggedness test factors on material properties and data quality indicators in the dynamic modulus test. Factors Control Dynamic Modulus Phase Angle Load Standard Deformation Deformation Phase Error Standard Error Uniformity Uniformity Equilibrium 0.5 C <6% < 0.6 < 0.5 % < 0.5 % <2% NS Temperature Transfer Time 3 versus 5 min NS NS NS NS NS < 0.5 Conditioning Fluid Air versus Water <6% <1 < 0.6 % < 0.5 % unconfined NS NS <7 % confined Strain Level 25 strain < 4 % unconfined < 1.6 < 0.6 % < 0.5 % unconfined NS < 0.7 < 12 % confined <1.7 % confined Membrane Without versus With < 11 percent 3.7 < 0.6 % < 4.6 % NS < 1.1 Confinement 2% < 0.8 % < 0.2 < 0.2 % NS NS < 0.1 End Condition Milled versus Sawed NS NS NS NS < 4.7 % NS Friction Reducer Greased Latex versus NS NS NS NS NS < 0.9 Teflon Acceptable 8% 1.7 5% 5% 10 % 1.5 NS = not statistically significant