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Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49 (2014)

Chapter: Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49

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Suggested Citation:"Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49 ." National Academies of Sciences, Engineering, and Medicine. 2014. Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49. Washington, DC: The National Academies Press. doi: 10.17226/22392.
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Suggested Citation:"Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49 ." National Academies of Sciences, Engineering, and Medicine. 2014. Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49. Washington, DC: The National Academies Press. doi: 10.17226/22392.
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Suggested Citation:"Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49 ." National Academies of Sciences, Engineering, and Medicine. 2014. Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49. Washington, DC: The National Academies Press. doi: 10.17226/22392.
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Suggested Citation:"Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49 ." National Academies of Sciences, Engineering, and Medicine. 2014. Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49. Washington, DC: The National Academies Press. doi: 10.17226/22392.
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Suggested Citation:"Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49 ." National Academies of Sciences, Engineering, and Medicine. 2014. Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49. Washington, DC: The National Academies Press. doi: 10.17226/22392.
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Suggested Citation:"Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49 ." National Academies of Sciences, Engineering, and Medicine. 2014. Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49. Washington, DC: The National Academies Press. doi: 10.17226/22392.
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Suggested Citation:"Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49 ." National Academies of Sciences, Engineering, and Medicine. 2014. Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49. Washington, DC: The National Academies Press. doi: 10.17226/22392.
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Suggested Citation:"Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49 ." National Academies of Sciences, Engineering, and Medicine. 2014. Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49. Washington, DC: The National Academies Press. doi: 10.17226/22392.
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Suggested Citation:"Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49 ." National Academies of Sciences, Engineering, and Medicine. 2014. Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49. Washington, DC: The National Academies Press. doi: 10.17226/22392.
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Suggested Citation:"Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49 ." National Academies of Sciences, Engineering, and Medicine. 2014. Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49. Washington, DC: The National Academies Press. doi: 10.17226/22392.
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Suggested Citation:"Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49 ." National Academies of Sciences, Engineering, and Medicine. 2014. Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49. Washington, DC: The National Academies Press. doi: 10.17226/22392.
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Suggested Citation:"Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49 ." National Academies of Sciences, Engineering, and Medicine. 2014. Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49. Washington, DC: The National Academies Press. doi: 10.17226/22392.
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Suggested Citation:"Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49 ." National Academies of Sciences, Engineering, and Medicine. 2014. Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49. Washington, DC: The National Academies Press. doi: 10.17226/22392.
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Suggested Citation:"Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49 ." National Academies of Sciences, Engineering, and Medicine. 2014. Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49. Washington, DC: The National Academies Press. doi: 10.17226/22392.
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Suggested Citation:"Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49 ." National Academies of Sciences, Engineering, and Medicine. 2014. Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49. Washington, DC: The National Academies Press. doi: 10.17226/22392.
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Suggested Citation:"Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49 ." National Academies of Sciences, Engineering, and Medicine. 2014. Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49. Washington, DC: The National Academies Press. doi: 10.17226/22392.
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Suggested Citation:"Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49 ." National Academies of Sciences, Engineering, and Medicine. 2014. Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49. Washington, DC: The National Academies Press. doi: 10.17226/22392.
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Suggested Citation:"Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49 ." National Academies of Sciences, Engineering, and Medicine. 2014. Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49. Washington, DC: The National Academies Press. doi: 10.17226/22392.
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Suggested Citation:"Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49 ." National Academies of Sciences, Engineering, and Medicine. 2014. Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49. Washington, DC: The National Academies Press. doi: 10.17226/22392.
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Suggested Citation:"Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49 ." National Academies of Sciences, Engineering, and Medicine. 2014. Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49. Washington, DC: The National Academies Press. doi: 10.17226/22392.
×
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Suggested Citation:"Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49 ." National Academies of Sciences, Engineering, and Medicine. 2014. Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49. Washington, DC: The National Academies Press. doi: 10.17226/22392.
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NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM Senior Program Officer: Edward T. Harrigan April 2014 C o n t e n t s Chapter 1—Introduction and Research Approach, 1 1.1 Background, 1 1.2 Research Objective, 1 1.3 Scope of Study, 2 1.4 Proficiency Samples Used in This Study, 2 Chapter 2—Analysis of Results, 3 2.1 Precision Estimates of T 201, 3 2.2 Precision Estimates of T 202, 6 2.3 Precision Estimates of T 49, 9 Chapter 3—Conclusions and Proposed Changes to standard test Methods, 16 3.1 Conclusions, 16 3.2 Proposed Changes to AASHTO Standard Test Methods T 201, T 202, and T 49, 17 References, 18 Unpublished Appendixes, 18 Appendix F, 18 Appendix G, 19 Appendix H, 19 PReCIsIon estIMAtes oF AAsHto t 201, AAsHto t 202, And AAsHto t 49 nCHRP Project 10-87, task order #2 This digest presents results of Task Order #2 of NCHRP Project 10-87, “Precision Statements for AASHTO Standard Methods of Test.” This work was conducted to update precision estimates of three test methods pertaining to asphalt binder: T 201, T 202, and T 49. Using the computed precision estimates, new precision statements for the three test methods have been prepared and are presented in this digest. The research was conducted by the AASHTO Materials Reference Laboratory. Dr. Haleh Azari was the Principal Investigator. Research Results Digest 388 CHAPteR 1—IntRodUCtIon And ReseARCH APPRoACH 1.1 Background Under NCHRP Project 10-87, the AASHTO Materials Reference Labora- tory (AMRL) is conducting a multi-phase research project to improve estimates of precision in AASHTO test methods for a wide range of construction materials. AMRL has an extensive database of test results for the broad range of construction materials collected through its proficiency sample program (PSP) that are used for developing the precision estimates (1). Laboratories participating in the AMRL PSP receive annual or biannual shipments of paired proficiency samples, which are tested according to specified AASHTO test methods. The results of the testing are returned to AMRL for analysis, summariza- tion, and reporting back to the participating laboratories. The number of participants in the AMRL PSP program is sufficiently large to ensure a statistically sound basis for determination of estimates of precision for standard test methods. The technique developed by AMRL in NCHRP Project 9-26 is used for analyzing proficiency sample data (2). This four-step statistical method removes outlying results and analyzes the core data of a paired data set. The results of the analysis can then be used to obtain reliable single-operator and multilaboratory estimates of precision. A summary of the analysis method is provided in Appendix A, which is not published herein, but can be found online at http://www.trb.org by searching for NCHRP Project 10-87. NCHRP RRD 388 presents the results from Task 2 of NCHRP Project 10-87 where data from the PSP testing program of viscosity graded asphalt cement (VGAC) were used to update precision estimates for AASHTO Standard Test Methods T 201, “Kinematic Viscosity of Asphalts (Bitu- mens)”; T 202, “Viscosity of Asphalts by Vacuum Capillary Viscometer”; and T 49, “Penetration of Bituminous Materials” (3–5). 1.2 Research objective The objective of Task 2 of NCHRP Proj- ect 10-87 was to update the precision esti- mates of AASHTO T 201, T 202, and T 49.

21.3 scope of study The scope of the project included the following major activities: 1. Update precision estimates of AASHTO T 201, T 202, and T 49. a. Organize the most recent sets of PSP data collected according to each test method. b. Analyze the data for determining single- operator and multilaboratory estimates of precision. c. Compare the existing and new precision estimates for each test method. 2. Draw conclusions and prepare proposed pre- cision statements for AASHTO T 201, T 202, and T 49. 1.4 Proficiency samples Used in this study Data collected by AMRL on a wide range of materials tested according to AASHTO T 201, T 202, and T 49 were used to update the precision estimates of the three test methods. Only the most recent pro- ficiency sample data were used to account for changes in precision estimates resulting from testing a wider range of materials and the effects of recent changes to the test methods. The researchers analyzed 168 sets of data, collected from the laboratories par- ticipating in the VGAC testing program of PSP. Table 1-1 provides information on the PSP sample rounds, which include the sample pair identifica- tion numbers, and the date the data was collected. Table 1-2 shows the number of data sets collected according to each test method on the original asphalt and rolling thin film oven (RTFO) residue at vari- ous temperatures. The sample instructions and data sheets sent to the laboratories for the VGAC test- ing program are provided in Appendix B, which is not published herein, but can be found online at http://www.trb.org by searching for NCHRP Proj- ect 10-87. table 1-1 List of 21 PSP rounds of viscosity graded asphalt cement (VGAC) samples for determining precision estimates of AASHTO T 201, T 202, and T 49. Round # PSP Sample No. Date 1 233-234 Nov. 2013 2 231-232 May 2013 3 229-230 Nov. 2012 4 227-228 May 2012 5 225-226 Nov. 2011 6 223-224 May 2011 7 221-222 Nov. 2010 8 219-220 April 2010 9 217-218 Nov. 2009 10 215-216 April 2009 11 213-214 Nov. 2008 12 211-212 April 2008 13 209-210 Nov. 2007 14 207-208 April 2007 15 205-206 Nov. 2006 16 203-204 May 2006 17 201-202 Dec. 2005 18 199-200 May 2005 19 197-198 Dec. 2004 20 195-196 May 2004 21 193-194 Dec. 2003 table 1-2 Number of PSP VGAC data sets used for determining precision estimates of AASHTO T 201, T 202, and T 49. Test Method Property Measured Material Test Temperature, C No. of Data Sets AASHTO T 201 Kinematic viscosity Original asphalt 135 42 RTFO residue AASHTO T 202 Viscosity by vacuum Capillary viscometer Original asphalt RTFO residue 60 42 AASHTO T 49 Penetration Original asphalt 4 42 25 RTFO residue 4 42 25 Total no. of data sets 168

3CHAPteR 2—AnALYsIs oF ResULts This chapter includes summaries of the data and the resulting precision estimates. The individual results for each of the 168 proficiency data sets analyzed in this study can be found in Appendixes C through E, which are not published herein, but can be found online at http://www.trb.org by searching for NCHRP Project 10-87. Using the most recent PSP data sets presented in Table 2-1, the precision estimates of T 201, T 202, and T 49 were updated. For each of the test methods, a summary of statistics of individual data sets used for the update of precision estimates as well as the pooled repeatability and reproducibility estimates are presented in the following sections. 2.1 Precision estimates of t 201 AASHTO T 201-10 is identical to ASTM D 2170-10 (6) except for several provisions described in AASHTO T 201-10. The test method covers pro- cedures for the determination of kinematic viscosity of liquid asphalts (bitumen) at 60°C and of asphalt cements at 135°C in the range of 6 to 100,000 mm2/s. A summary of statistics of the original and RTFO- aged kinematic viscosity of asphalt cements from the 21 most recent rounds of PSP VGAC program tested at 135°C according to AASHTO T 201 is provided in Table 2-1 and Table 2-2. The plots of the individual data pairs are found in Appendix C. A review of the data in the tables, as presented in Figure 2-1 and Figure 2-2, suggests that there is a relationship between the repeatability/reproducibility standard deviations and the average for both ori- ginal and RTFO binder (R2 = 0.43 to 0.85). Mean- while, there is no relationship between the average values and the repeatability or reproducibility coeffi- cient of variation of the original asphalt (R2 of 0.03 and 0.05) and a weak relationship between the average values and the coefficients of variation of the table 2-1 Summary of statistics for kinematic viscosity (AASHTO T 201) of 21 sets of original VGAC sample pairs. PSP Sample No. No. of Labs Reproducibility Average Results Repeatability X Samples Y Samples X mm2/s Y mm2/s 1s mm2/s X Samples CV% Y Samples CV% 1s mm2/s CV% 1s mm2/s CV% 233-234 85 377.2 387.1 6.90 1.8 1.8 9.66 2.6 10.43 2.7 231-232 76 465.1 469.2 4.48 1.0 1.0 8.47 1.8 8.90 1.9 229-230 75 559.5 555.2 7.66 1.4 1.4 14.17 2.5 14.24 2.6 227-228 80 409.3 410.8 4.34 1.1 1.1 9.22 2.3 9.18 2.2 225-226 79 508.3 509.0 5.58 1.1 1.1 11.20 2.2 11.07 2.2 223-224 79 445.1 508.5 6.36 1.4 1.3 11.97 2.7 10.62 2.1 221-222 81 443.3 443.2 6.08 1.4 1.4 8.25 1.9 8.60 1.9 219-220 75 445.2 448.9 4.06 0.9 0.9 6.53 1.5 7.65 1.7 217-218 80 540.9 542.3 4.28 0.8 0.8 9.79 1.8 9.47 1.7 215-216 87 390.9 390.2 2.95 0.8 0.8 6.74 1.7 6.24 1.6 213-214 86 447.9 449.6 3.90 0.9 0.9 7.84 1.7 8.49 1.9 211-212 90 444.9 444.7 6.36 1.4 1.4 9.97 2.2 10.28 2.3 209-210 89 434.7 435.4 4.14 1.0 1.0 9.19 2.1 10.00 2.3 207-208 99 286.6 286.0 3.08 1.1 1.1 6.11 2.1 6.00 2.1 205-207 104 531.0 535.0 5.91 1.1 1.1 13.44 2.5 12.35 2.3 203-204 115 392.7 393.9 6.56 1.7 1.7 10.30 2.6 11.50 2.9 201-202 116 462.0 464.4 7.86 1.7 1.7 14.30 3.1 13.30 2.9 199-200 107 283.0 283.5 4.15 1.5 1.5 6.70 2.4 7.90 2.8 197-198 111 489.0 488.9 10.99 2.2 2.2 18.50 3.8 15.30 3.1 195-196 116 702.3 700.9 14.12 2.0 2.0 21.70 3.1 20.60 2.9 193-194 118 470.3 469.1 9.54 2.0 2.0 11.40 2.4 13.80 3.0

4table 2-2 Summary of statistics for kinematic viscosity (AASHTO T 201) of 21 sets of rolling thin film oven (RTFO) aged VGAC sample pairs. PSP Sample No. No. of Labs Reproducibility Average Results Repeatability X Samples Y Samples X mm2/s Y mm2/s 1s mm2/s X Samples CV% Y Samples CV% 1s mm2/s CV% 1s mm2/s CV% 233-234 76 572.9 581.8 10.32 1.8 1.8 19.31 3.4 21.00 3.6 231-232 66 625.8 632.8 6.88 1.1 1.1 18.69 3.0 16.10 2.5 229-230 67 810.0 815.3 9.89 1.2 1.2 25.67 3.2 29.04 3.6 227-228 67 603.5 605.9 6.19 1.0 1.0 19.03 3.2 21.68 3.6 225-226 69 725.8 726.4 9.43 1.3 1.3 24.55 3.4 23.32 3.2 223-224 68 627.5 719.1 13.74 2.2 1.9 22.24 3.5 23.17 3.2 221-222 71 696.0 695.6 10.87 1.6 1.6 22.70 3.3 23.01 3.3 219-220 69 629.1 656.5 12.52 2.0 1.9 20.53 3.3 22.35 3.4 217-218 71 765.7 767.2 8.98 1.2 1.2 19.96 2.6 22.91 3.0 215-216 75 536.8 535.4 4.80 0.9 0.9 14.24 2.7 14.52 2.7 213-214 71 661.2 661.9 7.50 1.1 1.1 20.95 3.2 23.44 3.5 211-212 76 632.0 629.7 8.64 1.4 1.4 19.13 3.0 17.02 2.7 209-210 78 700.3 704.5 10.20 1.5 1.4 26.60 3.8 27.58 3.9 207-208 83 429.6 428.7 4.77 1.1 1.1 11.21 2.6 10.74 2.5 205-207 89 1,007.7 1,017.9 19.22 1.9 1.9 48.91 4.9 54.86 5.4 203-204 96 556.9 557.1 9.59 1.7 1.7 18.70 3.4 16.40 2.9 201-202 99 911.9 913.4 31.01 3.4 3.4 48.70 5.3 53.10 5.8 199-200 99 430.0 431.9 8.47 2.0 2.0 15.50 3.6 16.50 3.8 197-198 99 856.1 854.9 23.11 2.7 2.7 42.50 5.0 41.80 4.9 195-196 98 1,036.5 1,035.3 28.10 2.7 2.7 46.10 4.5 50.20 4.9 193-194 98 671.0 672.5 16.54 2.5 2.5 23.80 3.6 30.20 4.5 y = 0.02x - 2.91 R² = 0.43 0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 0.0 100.0 200.0 300.0 400.0 500.0 600.0 700.0 800.0 ST D, m m ²/s Average, mm²/s Repeatability Standard Deviation vs. Average (AASHTO T201-Original Binder) y = 0.00x + 0.95 R² = 0.03 0.0 0.5 1.0 1.5 2.0 2.5 0.0 100.0 200.0 300.0 400.0 500.0 600.0 700.0 800.0 CO V, % Average, mm²/s Repeatability Coefficient of Variation vs. Average (AASHTO T201-Original Binder) y = 0.03x - 3.53 R² = 0.61 0.00 5.00 10.00 15.00 20.00 25.00 0.0 100.0 200.0 300.0 400.0 500.0 600.0 700.0 800.0 ST D, m m ²/s Average, mm²/s Reproducibility Standard Deviation vs. Average (AASHTO T201-Original Binder) y = 0.00x + 1.80 R² = 0.05 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 0.0 100.0 200.0 300.0 400.0 500.0 600.0 700.0 800.0 CO V, % Average, mm²/s Reproducibility Coefficient of Variation vs. Average (AASHTO T201-Original Binder) Figure 2-1 Relationship between average and standard deviation and between average and coefficient of variation of kinematic viscosity (AASHTO T 201) test results for original asphalt.

5RTFO residue (R2 of 0.27 and 0.55). Therefore, as specified in ASTM C 670 (7), the form of the pre- cision estimates would be based on the sample coefficient of variation. The repeatability and repro- ducibility estimates of pre cision for the original and RTFO samples were then computed by averaging the coefficients of variation of the individual sam- ples in Table 2-1 and Table 2-2, respectively. The resulting precision estimates of AASHTO T 201 for the original and RTFO asphalts are provided in Table 2-3. 2.1.1 Comparison of the New and Existing Precision Estimates of AASHTO T 201 The precision statement of ASTM D 2170-10 does not provide separate precisions for the kinematic viscosity of the original and RTFO asphalt binders. The existing precision statement provides single- operator and multilaboratory coefficients of varia- tion for kinematic viscosity of asphalt cement at 135°C, which are shown in parentheses in Table 2-3. As indicated from the table, the new single-operator y = 0.04x - 12.10 R² = 0.63 0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 0.0 200.0 400.0 600.0 800.0 1000.0 1200.0 ST D, m m ²/s Average, mm²/s Repeatability Standard Deviation vs. Average (AASHTO T201-RTFO Residue) y = 0.00x + 0.24 R² = 0.27 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 0.0 200.0 400.0 600.0 800.0 1000.0 1200.0 CO V, % Average, mm²/s Repeatability Coefficient of Variation vs. Average (AASHTO T201-RTFO Residue) y = 0.07x - 21.05 R² = 0.85 0.00 10.00 20.00 30.00 40.00 50.00 60.00 0.0 200.0 400.0 600.0 800.0 1000.0 1200.0 ST D, m m ²/s Average, mm²/s Reproducibility Standard Deviation vs. Average (AASHTO T201-RTFO Residue) y = 0.00x + 0.95 R² = 0.55 0.0 1.0 2.0 3.0 4.0 5.0 6.0 0.0 200.0 400.0 600.0 800.0 1000.0 1200.0 CO V, % Average, mm²/s Reproducibility Coefficient of Variation vs. Average (AASHTO T201-RTFO Residue) Figure 2-2 Relationship between average and standard deviation and between average and coefficient of variation of kinematic viscosity (AASHTO T 201) test results for RTFO residue. table 2-3 Pooled repeatability and reproducibility precisions of T 201 based on samples’ coefficient of variation; the values in parentheses represent the current precision estimates in ASTM D 2170-10. Asphalt Statistics 1s (%) d2s (%) Original Repeatability Reproducibility 1.3 (0.64) 2.3 (3.1) 3.8 (1.8) 6.6 (8.8) RTFO (average of kinematic viscosity < 850 mm2/s) Repeatability Reproducibility 1.5 (0.64) 3.3 (0.64) 4.2 (1.8) 9.2 (1.8) RTFO (average of kinematic viscosity ≥ 850 mm2/s) Repeatability Reproducibility 2.7 (3.1) 5.1 (3.1) 7.6 (8.8) 14.4 (8.8)

6coefficient of variation for the original asphalt is 1.3% and for the RTFO residue is 1.7%. These values are significantly larger than the existing single-operator coefficient of variation of 0.64% for kinematic viscos- ity of asphalt cement at 135°C in ASTM D 2170-10. The new multilaboratory coefficient of variation for the original asphalt is 2.3% and for the RTFO residue is 3.6%. These values are compared with the existing multilaboratory coefficient of variation of 3.1% for kinematic viscosity of asphalt cement at 135°C. The new estimates of precision for kinematic viscosity of the original and RTFO asphalt binders are 25.8% smaller and 16.1% larger than the existing multilaboratory coefficient of variation, respectively. The reason for the significant difference in repeat- ability coefficient of variation is not clear since the range of kinematic viscosity values used for com- puting the existing precisions in ASTM D 2170-10 is not known. However, the difference between the existing and new reproducibility coefficients of vari- ation can be attributed to computing separate coeffi- cients of variation for the original asphalt and RTFO residue and to the fact that the variability of the RTFO test (AASHTO T 240) is also included in the vari- ability of the viscosity measurements. The average of the two multilaboratory coefficients of variation (3.0%) seems to be comparable with the existing multilaboratory coefficient of variation of 3.1%. 2.2 Precision estimates of t 202 AASHTO T 202-10 is identical to ASTM D 2171-10 (8) except for several provisions described in AASHTO T 202-10. The test method covers procedures for the determination of the viscosity of asphalt binder (bitumen) by vacuum capillary viscom - eters at 60°C. The test method is applicable to materials having viscosities in the range of 0.0036 to greater than 20,000 Pa s. A summary of statistics of the original and RTFO-aged viscosity by vacuum capillary of the 21 most recent pairs of PSP VGAC samples determined according to AASHTO T 202 is provided in Table 2-4 and Table 2-5. The plots of the individual data sets are found in Appendix D. table 2-4 Summary of statistics for viscosity of asphalt by vacuum capillary viscometer (AASHTO T 202) of 21 sets of original VGAC sample pairs. PSP Sample No. No. of Labs Repeatability Reproducibility Average Results 1s (Pa.s) X Samples CV% Y Samples CV% X Samples Y Samples X (Pa.s) Y (Pa.s) 1s (Pa.s) CV% 1s (Pa.s) CV% 233-234 114 203.5 216.6 4.21 2.1 1.9 6.33 3.1 6.77 3.1 231-232 111 263.3 268.0 3.79 1.4 1.4 7.39 2.8 8.16 3.0 229-230 107 310.0 298.3 6.63 2.1 2.2 8.56 2.8 10.48 3.5 227-228 102 228.4 229.0 1.95 0.9 0.8 5.94 2.6 6.13 2.7 225-226 98 304.0 303.9 2.81 0.9 0.9 7.55 2.5 7.24 2.4 223-224 94 210.2 301.7 3.35 1.6 1.1 4.84 2.3 7.29 2.4 221-222 104 225.7 224.6 2.19 1.0 1.0 6.68 3.0 7.05 3.1 219-220 107 210.2 214.7 2.75 1.3 1.3 6.01 2.9 7.27 3.4 217-218 105 340.5 341.7 3.09 0.9 0.9 7.32 2.1 7.92 2.3 215-216 109 178.8 179.0 1.51 0.8 0.8 3.90 2.2 3.94 2.2 213-214 100 214.0 214.3 2.01 0.9 0.9 6.53 3.1 6.71 3.1 211-212 111 211.1 209.2 2.67 1.3 1.3 5.44 2.6 5.53 2.6 209-210 113 416.9 420.8 5.97 1.4 1.4 12.21 2.9 12.22 2.9 207-208 107 102.3 101.3 1.01 1.0 1.0 1.96 1.9 2.11 2.1 205-207 128 309.8 316.8 4.60 1.5 1.5 11.29 3.6 11.66 3.7 203-204 133 1,941.0 1,948.6 29.58 1.5 1.5 59.00 3.0 61.40 3.2 201-202 131 2,153.3 2,145.3 39.41 1.8 1.8 101.60 4.7 92.70 4.3 199-200 128 955.9 959.8 22.39 2.3 2.3 32.20 3.4 36.40 3.8 197-198 135 2,232.8 2,266.1 60.57 2.7 2.7 118.70 5.3 110.60 4.9 195-196 130 5,930.7 5,919.6 144.45 2.4 2.4 202.70 3.4 221.00 3.7 193-194 130 2,282.4 2,278.2 32.26 1.4 1.4 80.90 3.5 86.30 3.8

7A review of the data in Table 2-4 and Table 2-5, as presented in Figure 2-3 and Figure 2-4, suggests that there are relationships between the standard devi- ations and the average viscosity values. Meanwhile, there are weak relationships between the average val- ues and the repeatability or reproducibility coefficient of variations. Therefore, the form of the precision estimates would be based on the sample coefficient of variation. The repeatability and reproducibility estimates of precision were then computed by aver- aging the coefficient of variations of the individual samples in Table 2-4 and Table 2-5. The resulted pre- cision estimates of the AASHTO T 202 are provided in Table 2-6. 2.2.1 Comparison of the New and Existing Precision Estimates of AASHTO T 202 The precision statement of ASTM D 2171-10 does not provide separate precisions for the viscos- ity by vacuum capillary of the original and RTFO asphalt binders. The existing statement provides d2s single-operator and multilaboratory coefficients of variation for viscosity by vacuum capillary at 60°C. These values are shown in parentheses in Table 2-6. The existing allowable difference between two rep- licate results is 7% of the mean. However, the new single-operator allowable difference between two replicate results is 4.1% of the mean for the original binder and 7.6% of the mean for the RTFO residue. The comparison of the existing and new precisions indicates a decrease of 39.4% (corresponding to original asphalt) and increase of 8.6% (corresponding to RTFO residue) in the single-operator coefficient of variation of viscosity by vacuum capillary. For multilaboratory precision, the existing ASTM statement sets the allowable difference between the results of two laboratories as 10% of the mean. However, the new precision estimates, broken into viscosity of original asphalt and RTFO residue, set the allowable difference between two laboratories’ results as 7.6% of the mean for the original asphalt and 19.0% of the mean for the RTFO residue. This is a decrease of 13.3% (corresponding to original asphalt) table 2-5 Summary of statistics for viscosity of asphalts by vacuum capillary viscometer (AASHTO T 202) of 21 sets of RTFO-aged sample pairs. PSP Sample No. No. of Labs Repeatability Reproducibility Average Results 1s (Pa.s) X Samples CV% Y Samples CV% X Sample X Sample X (Pa.s) Y (Pa.s) 1s (Pa.s) CV% 1s (Pa.s) CV% 233-234 100 537.8 556.1 19.05 3.5 3.4 28.57 5.3 29.08 5.2 231-232 93 532.1 540.5 10.76 2.0 2.0 25.56 4.8 24.00 4.4 229-230 91 749.7 758.6 13.91 1.9 1.8 42.19 5.6 43.80 5.8 227-228 93 528.6 534.6 10.67 2.0 2.0 30.60 5.8 29.93 5.6 225-226 87 694.1 702.4 15.24 2.2 2.2 38.43 5.5 40.74 5.8 223-224 86 480.7 699.2 17.87 3.7 2.6 29.50 6.1 44.31 6.3 221-222 91 604.6 602.4 12.99 2.1 2.2 39.32 6.5 39.97 6.6 219-220 94 484.2 561.1 24.68 5.1 4.4 33.08 6.8 49.52 8.8 217-218 92 765.8 763.5 11.77 1.5 1.5 38.99 5.1 39.34 5.2 215-216 87 403.5 404.1 6.09 1.5 1.5 21.32 5.3 21.22 5.3 213-214 88 567.7 566.2 10.03 1.8 1.8 34.85 6.1 34.34 6.1 211-212 92 478.2 474.8 8.57 1.8 1.8 24.30 5.1 25.14 5.3 209-210 92 1,200.5 1,209.5 29.12 2.4 2.4 87.26 7.3 87.55 7.2 207-208 94 264.6 261.9 6.94 2.6 2.6 18.14 6.9 15.97 6.1 205-207 106 1,477.4 1,497.9 48.79 3.3 3.3 145.30 9.8 154.49 10.3 203-204 115 4,690.6 4,683.6 140.22 3.0 3.0 318.80 6.8 303.90 6.5 201-202 115 10,120.1 10,105.7 379.67 3.8 3.8 1,133.00 11.2 1,092.70 10.8 199-200 116 2,544.0 2,546.7 75.80 3.0 3.0 202.40 8.0 194.90 7.7 197-198 114 7,450.5 7,493.7 224.97 3.0 3.0 652.70 8.8 671.60 9.0 195-196 109 11,585.7 11,554.9 477.46 4.1 4.1 852.00 7.4 884.10 7.7 193-194 105 5,927.3 5,964.6 203.62 3.4 3.4 459.00 7.7 436.50 7.3

8y = 0.02x - 3.71 R² = 0.96 -20.00 0.00 20.00 40.00 60.00 80.00 100.00 120.00 140.00 160.00 0.0 1000.0 2000.0 3000.0 4000.0 5000.0 6000.0 7000.0 ST D, P a. s Average, Pa.s Repeatability Standard Deviation vs. Average (AASHTO T202-Original Binder) y = 0.00x + 1.25 R² = 0.34 0.0 0.5 1.0 1.5 2.0 2.5 3.0 0.0 1000.0 2000.0 3000.0 4000.0 5000.0 6000.0 7000.0 CO V, % Average, Pa.s Repeatability Coefficient of Variation vs. Average (AASHTO T202-Original Binder) y = 0.04x - 1.13 R² = 0.97 0.00 50.00 100.00 150.00 200.00 250.00 0.0 1000.0 2000.0 3000.0 4000.0 5000.0 6000.0 7000.0 ST D, P a. s Average, Pa.s Reproducibility Standard Deviation vs. Average (AASHTO T202-Original Binder) y = 0.00x + 2.83 R² = 0.27 0.0 1.0 2.0 3.0 4.0 5.0 6.0 0.0 1000.0 2000.0 3000.0 4000.0 5000.0 6000.0 7000.0 CO V, % Average, Pa.s Reproducibility Coefficient of Variation vs. Average (AASHTO T202-Original Binder) Figure 2-3 Relationship between averages and standard deviations and between averages and coefficients of variation of the viscosity of asphalts by vacuum capillary viscometer of original asphalt (AASHTO T 202) test method. y = 0.04x - 12.25 R² = 0.98 -100.00 0.00 100.00 200.00 300.00 400.00 500.00 600.00 0.0 2000.0 4000.0 6000.0 8000.0 10000.0 12000.0 14000.0 ST D, P a. s Average, Pa.s Repeatability Standard Deviation vs. Average (AASHTO T202-RTFO Residue) y = 0.00x + 2.35 R² = 0.30 0.0 1.0 2.0 3.0 4.0 5.0 0.0 2000.0 4000.0 6000.0 8000.0 10000.0 12000.0 14000.0 CO V, % Average, Pa.s Repeatability Coefficient of Variation vs. Average (AASHTO T202-RTFO Residue) y = 0.09x - 19.39 R² = 0.95 0.00 200.00 400.00 600.00 800.00 1000.00 1200.00 0.0 2000.0 4000.0 6000.0 8000.0 10000.0 12000.0 14000.0 ST D, Pa .s Average, Pa.s Reproducibility Standard Deviation vs. Average (AASHTO T202-RTFO Residue) y = 0.00x + 6.02 R² = 0.40 0.0 2.0 4.0 6.0 8.0 10.0 12.0 0.0 2000.0 4000.0 6000.0 8000.0 10000.0 12000.0 14000.0 CO V, % Average, Pa.s Reproducibility Coefficient of Variation vs. Average (AASHTO T202-RTFO Residue) Figure 2-4 Relationship between averages and standard deviations and between averages and coefficients of variation of the viscosity of asphalt by vacuum capillary viscometer of RTFO residue (AASHTO T 202) test method.

9and increase of 89% (corresponding to RTFO residue) in the multilaboratory coefficient of variation of vis- cosity by vacuum capillary. The reason for the significant difference in repeat- ability coefficients of variation is not clear since the range of viscosity by vacuum capillary values used for computing the existing estimates of precision is not known. However, the differences between the existing and new reproducibility coefficients of variation could be attributed to computing separate coefficients of variation for the original asphalt and RTFO residue and the fact that the variability of the RTFO test (AASHTO T 240) is added to the vari- ability of viscosity measurements. 2.3 Precision estimates of t 49 AASHTO T 49-07 is identical to ASTM D 5-06 (9) except for several provisions described in AASHTO T 49-07. The test method covers determination of the penetration of semi-solid and solid bituminous materials. The conditions described in the test method provide for the determinations of penetrations up to 500 units. A summary of statistics of penetration of the original asphalt and RTFO residue from the 19 most recent PSP VGAC sample pairs tested at 4°C and 25°C according to T 49 is provided in Table 2-7 through Table 2-10. The plots of the individual data sets are found in Appendix E. A review of the data in Tables 2-7 through 2-10, as presented in Figure 2-5 though Figure 2-8, indicates table 2-6 Pooled repeatability and reproducibility precisions of T 202 based on samples’ coefficient of variation. Asphalt Statistics 1s (%) d2s (%) Original Repeatability Reproducibility 1.5 3.1 4.2 (7) 8.8 (10) RTFO Repeatability Reproducibility 2.7 6.8 7.7 (7) 19.2 (10) table 2-7 Summary of statistics for penetration (AASHTO T 49) of original asphalts at 4°C of 21 sets of VGAC sample pairs. PSP Sample No. No. of Labs Repeatability Reproducibility Average Results 1s, Units X Samples CV% Y Samples CV% X Samples Y Samples X, Units Y, Units 1s, Units CV% 1s, Units CV% 233-234 90 21.5 20.7 1.09 5.1 5.3 3.24 15.1 3.46 16.8 231-232 81 18.6 18.4 0.74 4.0 4.0 2.86 15.3 2.98 16.2 229-230 85 20.3 20.3 1.12 5.5 5.5 2.76 13.6 2.85 14.1 227-228 77 28.0 28.2 0.95 3.4 3.4 3.86 13.8 3.71 13.1 225-226 80 18.8 18.6 0.89 4.7 4.8 3.00 15.9 2.87 15.4 223-224 71 24.1 19.3 1.67 6.9 8.6 4.18 17.3 3.75 19.5 221-222 79 30.7 30.9 0.88 2.9 2.8 3.72 12.1 3.63 11.7 219-220 75 23.1 24.0 0.95 4.1 4.0 3.25 14.0 3.15 13.1 217-218 78 18.7 18.8 0.60 3.2 3.2 3.11 16.6 3.06 16.3 215-216 75 22.0 22.0 0.62 2.8 2.8 2.80 12.7 2.61 11.9 213-214 79 23.8 23.8 0.65 2.7 2.7 3.21 13.5 3.15 13.2 211-212 82 23.3 23.4 0.71 3.0 3.0 3.17 13.6 3.04 13.0 209-210 89 11.7 11.8 0.57 4.9 4.9 2.71 23.1 2.68 22.8 207-208 84 39.3 39.6 0.86 2.2 2.2 4.02 10.2 3.98 10.1 205-207 90 28.6 28.6 0.83 2.9 2.9 3.48 12.2 3.48 12.2 203-204 92 19.1 19.0 1.07 5.6 5.7 3.60 19.0 3.90 20.4 201-202 89 42.3 42.3 0.94 2.2 2.2 4.40 10.5 4.60 10.8 199-200 91 43.8 44.0 1.25 2.9 2.9 5.00 11.4 5.20 11.9 197-198 94 34.3 34.3 0.99 2.9 2.9 3.70 10.9 3.70 10.7 195-196 97 16.7 16.5 0.92 5.5 5.5 3.10 18.7 3.10 18.7 193-194 93 21.1 20.8 1.04 4.9 5.0 3.20 15.2 3.10 14.7

10 table 2-8 Summary of statistics for penetration (AASHTO T 49) of RTFO-aged asphalts at 4°C of 21 sets of VGAC sample pairs. PSP Sample No. No. of Labs Repeatability Reproducibility Average Results 1s, Units X Samples CV% Y Samples CV% X Samples Y Samples X, Units Y, Units 1s, Units CV% 1s, Units CV% 233-234 85 14.8 14.3 0.92 6.2 6.4 2.40 16.2 2.47 17.3 231-232 74 14.1 14.2 0.77 5.4 5.4 2.64 18.7 2.47 17.3 229-230 71 14.7 15.0 0.69 4.7 4.6 1.74 11.8 1.76 11.7 227-228 68 20.6 20.8 0.59 2.9 2.8 2.30 11.1 2.35 11.3 225-226 72 13.9 14.0 0.76 5.5 5.5 2.22 15.9 2.24 16.0 223-224 64 17.3 13.9 1.24 7.2 8.9 2.15 12.4 2.40 17.3 221-222 68 21.5 21.4 0.79 3.7 3.7 2.65 12.4 2.59 12.1 219-220 66 17.4 17.5 0.91 5.2 5.2 2.27 13.0 2.06 11.8 217-218 72 14.3 14.3 0.63 4.4 4.4 2.87 20.1 2.86 20.1 215-216 68 16.2 16.1 0.55 3.4 3.4 2.55 15.7 2.27 14.0 213-214 77 17.3 17.3 0.65 3.7 3.8 3.06 17.7 2.89 16.7 211-212 75 17.2 17.2 0.59 3.4 3.4 2.68 15.5 2.77 16.1 209-210 79 7.9 7.8 0.55 6.9 7.0 2.26 28.7 2.15 27.6 207-208 78 25.9 26.2 1.04 4.0 4.0 2.85 11.0 2.87 11.0 205-207 84 19.5 19.5 0.81 4.2 4.2 2.18 11.2 2.07 10.6 203-204 87 13.8 13.9 0.81 5.9 5.9 3.10 22.4 2.90 20.9 201-202 86 27.2 26.8 1.33 4.9 5.0 4.00 14.8 3.70 13.7 199-200 87 26.8 26.9 1.07 4.0 4.0 3.90 14.7 4.10 15.1 197-198 87 21.8 21.8 0.77 3.5 3.5 2.50 11.5 2.80 12.6 195-196 85 14.0 14.0 0.77 5.5 5.5 3.10 21.9 3.10 21.9 193-194 78 16.1 16.1 0.84 5.2 5.2 2.40 15.0 2.50 15.4 table 2-9 Summary of statistics for penetration (AASHTO T 49) of original asphalts at 25°C of 21 sets of VGAC sample pairs. Repeatability Reproducibility PSP Sample No. No. of Labs Average Results 1s, Units X Samples CV% Y Samples CV% X Samples Y Samples X, Units Y, Units 1s, Units CV% 1s, Units CV% 233-234 153 63.8 61.4 1.70 2.7 2.8 3.31 5.2 3.23 5.3 231-232 141 55.2 54.9 0.88 1.6 1.6 3.17 5.7 3.26 5.9 229-230 137 55.5 56.1 1.06 1.9 1.9 2.41 4.4 2.60 4.6 227-228 141 74.0 73.5 1.34 1.8 1.8 2.76 3.7 2.94 4.0 225-226 132 51.9 52.0 1.02 2.0 2.0 2.69 5.2 2.81 5.4 223-224 126 68.2 52.7 1.83 2.7 3.5 4.11 6.0 3.60 6.8 221-222 123 81.7 82.2 0.87 1.1 1.1 3.25 4.0 3.12 3.8 219-220 132 68.9 70.3 1.39 2.0 2.0 3.19 4.6 3.16 4.5 217-218 127 49.6 49.6 0.70 1.4 1.4 2.86 5.8 2.93 5.9 215-216 138 65.6 65.7 1.11 1.7 1.7 3.26 5.0 3.24 4.9 213-214 135 70.9 71.0 0.81 1.1 1.1 3.81 5.4 3.75 5.3 211-212 139 68.0 68.4 0.96 1.4 1.4 3.49 5.1 3.35 4.9 209-210 138 33.4 33.5 0.86 2.6 2.6 2.50 7.5 2.78 8.3 207-208 140 116.1 116.7 1.34 1.2 1.1 4.98 4.3 4.94 4.2 205-207 147 68.0 67.5 0.99 1.5 1.5 2.79 4.1 2.82 4.2

11 203-204 156 54.9 54.8 1.67 3.0 3.0 3.30 6.1 3.30 6.0 201-202 154 92.6 92.4 1.79 1.9 1.9 4.80 5.2 4.80 5.2 199-200 152 128.9 128.7 2.09 1.6 1.6 6.60 5.1 6.30 4.9 197-198 153 88.9 88.6 1.42 1.6 1.6 3.70 4.2 3.40 3.8 195-196 157 39.5 39.7 1.39 3.5 3.5 3.40 8.5 3.40 8.4 193-194 164 56.2 56.4 1.42 2.5 2.5 3.50 6.2 3.60 6.5 table 2-9 (Continued) Repeatability Reproducibility PSP Sample No. No. of Labs Average Results 1s, Units X Samples CV% Y Samples CV% X Samples Y Samples X, Units Y, Units 1s, Units CV% 1s, Units CV% table 2-10 Summary of statistics for penetration (AASHTO T 49) of RTFO asphalt at 25°C of 21 sets of VGAC sample pairs. Repeatability Reproducibility PSP Sample No. No. of Labs Average Results 1s, Units X Samples CV% Y Samples CV% X Samples Y Samples X, Units Y, Units 1s, Units CV% 1s, Units CV% 233-234 114 37.4 35.9 1.11 3.0 3.1 2.34 6.2 2.35 6.5 231-232 115 36.6 36.3 0.92 2.5 2.5 2.65 7.2 2.72 7.5 229-230 103 35.8 35.5 0.76 2.1 2.1 2.00 5.6 2.07 5.8 227-228 118 48.0 47.7 0.87 1.8 1.8 2.76 5.7 2.53 5.3 225-226 101 33.9 33.9 0.99 2.9 2.9 1.75 5.2 1.76 5.2 223-224 101 43.1 34.0 1.48 3.4 4.4 3.25 7.5 2.73 8.0 221-222 106 49.3 49.4 1.04 2.1 2.1 2.58 5.2 2.67 5.4 219-220 97 42.9 42.8 1.18 2.7 2.8 2.17 5.1 2.14 5.0 217-218 98 32.5 32.6 0.75 2.3 2.3 2.15 6.6 2.03 6.2 215-216 105 41.4 41.5 0.76 1.8 1.8 3.08 7.4 2.83 6.8 213-214 105 43.1 43.0 0.70 1.6 1.6 2.96 6.9 3.09 7.2 211-212 109 43.4 43.5 1.01 2.3 2.3 2.59 6.0 2.46 5.7 209-210 109 19.8 19.8 0.65 3.3 3.3 2.21 11.2 2.21 11.2 207-208 112 64.6 64.7 1.20 1.9 1.9 3.35 5.2 3.58 5.5 205-207 122 39.0 38.8 1.00 2.6 2.6 2.53 6.5 2.52 6.5 203-204 123 33.6 33.8 0.91 2.7 2.7 2.50 7.5 2.50 7.4 201-202 121 50.1 50.0 1.33 2.7 2.7 3.40 6.7 3.40 6.8 199-200 121 68.4 67.9 1.62 2.4 2.4 4.20 6.2 3.90 5.7 197-198 126 49.0 49.2 1.45 3.0 3.0 3.40 7.0 3.30 6.7 195-196 124 31.8 32.1 1.23 3.9 3.8 3.00 9.5 3.00 9.3 193-194 127 37.0 36.9 1.18 3.2 3.2 2.90 7.7 2.80 7.6 that there could be moderate to strong relation- ships between the average and both the standard deviations and coefficients of variation. Accord- ing to ASTM C 670 (7), since both standard devia- tion and coefficient of variation are functions of the average value, the equation of the lines of best fit to the averages and standard deviations would be used for determining the precision estimates. The resulting precision estimates of AASHTO T 49 are provided in Table 2-11. 2.3.1 Comparison of the New and Existing Precision Estimates of AASHTO T 49 The existing precision statement in ASTM D5-06 includes six single-operator and multilaboratory

12 y = 0.01x + 0.75 R² = 0.05 0 0.5 1 1.5 2 0 10 20 30 40 50 ST D, U ni ts Average, Units Repeatability Standard Deviation vs. Average (AASHTO T49-Original Binder, 4°C) y = -0.10x + 6.38 R² = 0.40 0 1 2 3 4 5 6 7 8 0 10 20 30 40 50 CO V, % Average, Units Repeatability Coefficient of Variation vs. Average (AASHTO T49-Original Binder, 4°C) y = 0.06x + 1.94 R² = 0.71 0 1 2 3 4 5 6 0 10 20 30 40 50 ST D, U ni ts Average, Units Reproducibility Standard Deviation vs. Average (AASHTO T49-Original Binder, 4°C) y = -0.30x + 22.16 R² = 0.66 0 5 10 15 20 25 0 10 20 30 40 50 CO V, % Average, Units Reproducibility Coefficient of Variation vs. Average (AASHTO T49-Original Binder, 4°C) Figure 2-5 Relationship between average and standard deviation and between average and coefficient of variation for penetration (AASHTO T 49) of original asphalts at 4°C. y = 0.02x + 0.39 R² = 0.31 0 0.2 0.4 0.6 0.8 1 1.2 1.4 0 5 10 15 20 25 30 ST D, U ni ts Average, Units Repeatability Standard Deviation vs. Average (AASHTO T49-RTFO Residue, 4°C) y = -0.14x + 7.25 R² = 0.33 0 1 2 3 4 5 6 7 8 0 5 10 15 20 25 30 CO V, % Average, Units Repeatability Coefficient of Variation vs. Average (AASHTO T49-RTFO Residue, 4°C) y = 0.06x + 1.51 R² = 0.33 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 0 5 10 15 20 25 30 ST D, U ni ts Average, Units Reproducibility Standard Deviation vs. Average (AASHTO T49-RTFO Residue, 4°C) y = -0.62x + 26.73 R² = 0.44 0 5 10 15 20 25 30 35 0 5 10 15 20 25 30 CO V, % Average, Units Reproducibility Coefficient of Variation vs. Average (AASHTO T49-RTFO Residue, 4°C) Figure 2-6 Relationship between average and standard deviation and between average and coefficient of variation for penetration (AASHTO T 49) of RTFO residue at 4°C.

13 y = 0.01x + 0.73 R² = 0.21 0 0.5 1 1.5 2 2.5 0 20 40 60 80 100 120 140 Average, Units Repeatability Standard Deviation vs. Average (AASHTO T49-Original Binder, 25°C) y = -0.02x + 2.99 R² = 0.29 0 0.5 1 1.5 2 2.5 3 3.5 4 0 20 40 60 80 100 120 140 CO V, % Average, Units Repeatability Coefficient of Variation vs. Average (AASHTO T49-Original Binder, 25°C) y = 0.03x + 1.25 R² = 0.68 0 1 2 3 4 5 6 7 0 20 40 60 80 100 120 140 ST D , U ni ts Average, Units Reproducibility Standard Deviation vs. Average (AASHTO T49-Original Binder, 25°C) y = -0.03x + 7.30 R² = 0.33 0 1 2 3 4 5 6 7 8 9 0 20 40 60 80 100 120 140 CO V, % Average, Units Reproducibility Coefficient of Variation vs. Average (AASHTO T49-Original Binder, 25°C) ST D , U ni ts Figure 2-7 Relationship between average and standard deviation and between average and coefficient of variation for penetration (AASHTO T 49) of original asphalts at 25°C. Figure 2-8 Relationship between average and standard deviation and between average and coefficient of variation for penetration (AASHTO T 49) of RTFO residue at 25°C. y = 0.01x + 0.46 R² = 0.33 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 0 10 20 30 40 50 60 70 80 ST D, U ni ts Average, Units Repeatability Standard Deviation vs. Average (AASHTO T49-RTFO Residue, 25°C) y = -0.03x + 3.64 R² = 0.21 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 0 10 20 30 40 50 60 70 80 CO V, % Average, Units Repeatability Coefficient of Variation vs. Average (AASHTO T49-RTFO Residue, 25°C) y = 0.04x + 1.11 R² = 0.56 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 0 10 20 30 40 50 60 70 80 ST D, U ni ts Average, Units Reproducibility Standard Deviation vs. Average (AASHTO T49-RTFO Residue, 25°C) y = -0.08x + 10.05 R² = 0.34 0 2 4 6 8 10 12 0 10 20 30 40 50 60 70 80 CO V, % Average, Units Reproducibility Coefficient of Variation vs. Average (AASHTO T49-RTFO Residue, 25°C)

14 precision estimate equations for the penetration values at 4°C and 25°C. For 4°C, there is one equation for each single-operator and multilaboratory precision. For 25°C, there are two equations for each single- operator and multilaboratory precision based on the penetration values below and above 60 units. The range of average penetration values is reported as 29 to 286 units. The new single-operator and multilaboratory precision estimates are each divided into four equations corresponding to original asphalt and RTFO residue samples, each tested at 4°C and 25°C. The range of the average penetration values used for computing the new precisions are 8 to 129 units. Table 2-11 provides the existing and the new pre- cision equations. In the equations, s is 1s repeatability standard deviation and X is the average value of the two test results. The maximum allowable difference between two results (d2s) in a single laboratory and between two laboratories can be determined by multi- plying the standard deviation estimates provided in Table 2-11 by a factor of 2.83. Figure 2-9 and Figure 2-10 demonstrate the existing and new single-operator and multilabora- tory standard deviation equations along with the standard deviation values calculated from the PSP original asphalt and RTFO residue penetration results. In the figures, the existing equations are shown by a solid line, the new equations are shown by a dashed line, and the PSP standard deviations are shown by triangle points. The comparisons of the existing and new precision equations using Figure 2-9 and Figure 2-10 are explained in the subsequent paragraphs. Comparison at 4°C. Figure 2-9 presents the new and existing equations for the repeatability and reproducibility standard deviations for penetra- tion of original asphalt and RTFO residue at 4°C. The actual standard deviations computed from the PSP penetration data at 4°C are also shown in the graph. The new equations provide separate standard deviations for the original asphalt and RTFO residue; however, the existing equation does not distinguish between original asphalt and RTFO residue. As indicated, for the range of penetration values of the original asphalt (11.7 to 44.0 units) and RTFO residue (7.8 to 27.2 units), the new set of equations (dashed line) provide smaller repeatability standard deviation values than the existing equation (solid line). Similarly, the new equations for multilaboratory standard deviation provide smaller standard deviations for both original asphalt and RTFO asphalt than does the existing equation. Comparison at 25°C. Figure 2-10 presents the equations for the repeatability and reproducibility standard deviations of penetration for the orig inal asphalt and RTFO residue at 25°C. The actual stan- dard deviation values computed from the PSP pen- etration data at 25°C are also shown in the graph. The new equations provide separate standard devia- tions for the original asphalt and the RTFO residue. On the other hand, the existing equations provide a separate set of standard deviations based on the level of penetration above and below 60 units, which could correspond to penetration of original asphalt and RTFO residue, respectively. As indicated from the graphs, the new repeatability equation for the table 2-11 The new and existing repeatability and reproducibility precision equations of AASHTO T 49 based on samples’ standard deviations. Test Temperature Material Statistics New 1s (units) Existing 1s (units) 4°C Original Repeatability s = 0.01X + 0.8 s = 0.02X + 0.8 Reproducibility s = 0.06X + 1.9 s = 0.08X + 2.5 RTFO Repeatability s = 0.02X + 0.4 s = 0.02X + 0.8 Reproducibility s = 0.06X + 1.5 s = 0.08X + 2.5 25°C Original Repeatability s = 0.01X + 0.7 s = 0.03(X - 60) + 0.8 when X > 60 Reproducibility s = 0.03X + 1.3 s = 0.05(X - 60) + 2.5 when X > 60 RTFO Repeatability s = 0.01X + 0.5 s = 0.8 where X < 60 Reproducibility s = 0.04X + 1.2 s = 2.5 when X < 60 Note: X is the average penetration value (Units) and s is the 1s repeatability standard deviation (Units).

y = 0.01x + 0.75 R² = 0.05 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 0 10 20 30 40 50 ST D, U ni ts Average, Units Repeatability Standard Deviation vs. Average (AASHTO T49-Original Binder, 4°C) Existing New Actual y = 0.06x + 1.94 R² = 0.71 0 1 2 3 4 5 6 7 0 10 20 30 40 50 ST D, U ni ts Average, Units Reproducibility Standard Deviation vs. Average (AASHTO T49-Original Binder, 4°C) Existing New Actual y = 0.02x + 0.39 R² = 0.31 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 5 10 15 20 25 30 ST D, U ni ts Average, Units Repeatability Standard Deviation vs. Average (AASHTO T49-RTFO Residue, 4°C) Actual Existing New y = 0.06x + 1.51 R² = 0.33 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 0 5 10 15 20 25 30 ST D, U ni ts Average, Units Reproducibility Standard Deviation vs. Average (AASHTO T49-RTFO Residue, 4°C) Actual Existing New Figure 2-9 Comparison of the existing and new repeatability/reproducibility standard deviations for penetration (AASHTO T 49) of original binder and RTFO residue at 4°C. y = 0.01x + 0.73 R² = 0.21 0 0.5 1 1.5 2 2.5 3 3.5 0 20 40 60 80 100 120 140 ST D, U ni ts Average, Units Repeatability Standard Deviation vs. Average (AASHTO T49-Original Asphalt, 25°C) Actual Existing New y = 0.03x + 1.25 R² = 0.68 0 1 2 3 4 5 6 7 0 20 40 60 80 100 120 140 ST D, U ni ts Average, Units Reproducibility Standard Deviation vs. Average (AASHTO T49-Original Asphalt, 25°C) Actual Existing New y = 0.01x + 0.46 R² = 0.33 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 0 20 40 60 80 ST D, U ni ts Average, Units Repeatability Standard Deviation vs. Average (AASHTO T49-RTFO Residue, 25°C) Actual Existing New y = 0.04x + 1.15 R² = 0.55 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 0 20 40 60 80 ST D, U ni ts Average, Units Reproducibility Standard Deviation vs. Average (AASHTO T49-RTFO Residue, 25°C) Actual Existing New Figure 2-10 Comparison of the existing and new repeatability and reproducibility standard deviations for penetration (AASHTO T 49) of original binder and RTFO residue at 25°C.

16 original asphalt provides larger standard deviation values than do the existing equations for the range of penetration of 30 to 80 units. For the average pen etration larger than 80 units, the new equation provides smaller standard deviations than does the existing equation. On the other hand, the new repeat- ability equation for the standard deviation of RTFO residue at 25°C provides larger standard deviation values than does the existing equation for a range of 30 to 70 units. As is shown in Figure 2-10, the new equations for multilaboratory standard deviation provide larger standard deviation values than do the existing equations for the penetration range of 30 to 85 units. For the average penetration values above 85 units, the new equation provides smaller standard devia- tions than does the existing equation. For the re- producibility standard deviation of RTFO residue at 25°C, the new equation provides smaller stan- dard deviation for penetration of less than 35 units and larger standard deviation values than does the existing equation for average penetration values larger than 35 units. CHAPteR 3—ConCLUsIons And PRoPosed CHAnGes to stAndARd test MetHods 3.1 Conclusions This study was conducted under Task 2 of NCHRP Project 10-87 to update precision estimates of three AASHTO test methods pertaining to asphalt binder: T 201, “Kinematic Viscosity of Asphalts (Bitumens),” T 202, “Viscosity of Asphalts by Vacuum Capillary Viscometer,” and T 49, “Penetration of Bituminous Materials.” AMRL PSP data were used to compute the estimates of precision. The data collected in- clude the test properties of both original asphalt and RTFO residue of the 21 most recent pairs of PSP VGAC samples tested according to AASHTO T 201, T 202, and T 49. The study conclusions and proposals are detailed in the following sections. 3.1.1 AASHTO T 201 For AASHTO T 201-10, which is identical to ASTM D 2170-10, the new set of precision esti- mates includes separate coefficients of variation for the kinematic viscosity of the original and RTFO asphalt binders. The existing precision statement provides a single set of coefficients of variation for asphalt cement, which are significantly smaller than the new set of coefficients of variation. The existing single-operator repeatability precision for kinematic viscosity of asphalt at 135°C is 0.64%, while the new precisions corresponding to origi- nal asphalt and RTFO residue are 1.3% and 1.7%, respectively. The existing multilaboratory coefficient of vari- ation for kinematic viscosity of asphalt cement at 135°C is 3.1%; however, the new multilaboratory coefficient of variation for the original asphalt is 2.3% and for the RTFO residue is 3.6%. The aver- age of the new multilaboratory coefficients of vari- ation from the original asphalt and RTFO residue are equivalent to the existing multilaboratory coef- ficient of variation. The differences between the new and existing repeatability precisions may arise from analyz- ing a wider range of kinematic viscosity values for the new precisions than those used for the existing precisions. Moreover, the difference between the new and existing reproducibility precisions may arise from separating the precisions for the original asphalt and RTFO residue. The variability of the kinematic viscosity of the RTFO residue is expected to be larger than that of original asphalt since the variability of the RTFO aging (AASHTO T 240) is also included in the variability of the viscosity measurements. 3.1.2 AASHTO T 202 For AASHTO T 202-10, which is identical to ASTM D 2171-10, the new set of precisions includes separate coefficients of variation for the viscosity by capillary vacuum of the original as- phalt and RTFO residue tested at 60°C. The ex- isting precision statement provides a single set of precisions for asphalt cement tested at 60°C, which are significantly different from the new set of precisions. The existing allowable difference between two replicate results is 7% of the mean; however, the new allowable difference between two replicate results is 4.1% of the mean for the original binder and 7.6% of the mean for the RTFO residue. The existing allowable difference between the results of two laboratories is 10% of the mean.

17 However, the new precision estimates, separated between the viscosity of original asphalt and the RTFO residue, set the allowable difference between two laboratories’ results as 8.8% of the mean for the original asphalt and 19.7% of the mean for the RTFO residue. The differences in the new and existing precisions may arise from using a wider range of asphalt binders for preparing the new precision estimates than those used for preparing the existing precisions, although this cannot be confirmed. The difference could also be due to separating the precisions for the original asphalt and RTFO residue, resulting in smaller pre- cision estimates than the existing one for the original asphalt and larger precision estimates than the exist- ing for the RTFO residue. This is expected because, for the RTFO residue, the variability of RTFO aging would be included in the variability of viscosity measurements. 3.1.3 AASHTO T 49 AASHTO T 49-07 is identical to ASTM D 5-06 except for several provisions described in AASHTO T 49-07. The existing precision statement in ASTM D5-06 includes six single-operator and multilabora- tory precision estimate equations for the penetration values at 4°C and 25°C. For 4°C, there is one equa- tion for each single-operator and multilaboratory precision. For 25°C, there are two equations for each single-operator and multilaboratory precision based on the penetration values below and above 60 units. The range of average penetration values is reported as 29 to 286 units. The new precision estimate breaks each single- operator and multilaboratory precision estimate into four equations based on the results from the original and the RTFO binder samples tested at 4°C and 25°C. The new precisions cover a range of penetration values from 8 to 129 units. 3.1.3.1 Comparison at 4°C. The comparison of existing and new precision estimate values indi- cated that at 4°C, the new set of equations pro- vide smaller repeatability standard deviation val- ues than the existing equation. Similarly, the new equations for multilaboratory standard deviation provide smaller standard deviations for both origi- nal asphalt and RTFO residue than does the existing equation (see Figure 2-9). 3.1.3.2 Comparison at 25°C. At 25°C, the new re- peatability equation for the original asphalt pro vides larger standard deviation values than do the exist- ing equations for penetration less than 80 units and smaller standard deviation values than do the exist- ing equations for pene tration larger than 80 units. The new repeatability equation for the standard deviation of RTFO residue at 25°C provides larger standard deviation values than does the existing equation for penetration values above 25 units (see Figure 2-10). The new equations for multilaboratory standard deviation at 25°C provide larger standard deviation values than do the existing equations for the penetra- tion values larger than 30 and smaller than 100 units. For the penetration values larger than 100 units, the new equation provides a smaller standard devia- tion than does the existing equation. For the RTFO residue at 25°C, the new equation provides a smaller standard deviation for a penetration less than 35 units and larger standard deviation values than does the existing equation for a penetration above 35 units (see Figure 2-10). The observed differences between the new and existing precisions may arise from (1) testing asphalt binders with a different range of penetration values collected most recently as part of the AMRL PSP; (2) separating the precision estimates of the original asphalt and RTFO residue; (3) using the new AMRL statistical analysis method, which began in 2004, while the existing precision estimates were devel- oped based on an older analysis method; and (4) any improvements to the test method that would not be reflected in the results collected at the time when the existing precisions were developed. 3.2 Proposed Changes to AAsHto standard test Methods t 201, t 202, and t 49 The following changes are proposed on the basis of the differences observed between the ex- isting precision estimates and those developed in this study. 3.2.1 AASHTO T 201 It is proposed that the precision and bias state- ment in Appendix F be adopted for AASHTO T 201. This is in consideration of the differences between the current precision estimates in ASTM D 2170 and those developed in this study.

18 3.2.2 AASHTO T 202 It is proposed that the precision and bias state- ment in Appendix G be adopted for AASHTO T 202. This is in consideration of the differences between the current repeatability and reproducibility precision estimates in ASTM D 2171 and those developed in this study. 3.2.3 AASHTO T 49 It is proposed that the precision and bias statement in Appendix H be adopted for AASHTO T 49. This is in consideration of the differences between the repeatability and reproducibility precision estimates of the current ASTM D5-06 and those developed in this study. ReFeRenCes 1. AMRL website, http://www.amrl.net/amrlsitefinity/ default.aspx. 2. Holsinger, R., A. Fisher, and P. Spellerberg. NCHRP Web-Only Document 71: Precision Estimates for AASHTO Test Method T308 and the Test Methods for Performance-Graded Asphalt Binder in AASHTO Specification M320. Transportation Research Board of the National Academies, 2005. 3. AASHTO, Designation T 201, “Kinematic Viscosity of Asphalts (Bitumens)” Standard Specifications for Transportation Materials and Methods of Sampling and Testing, 32nd Edition, AASHTO, Washington, DC, 2012. 4. AASHTO, Designation T 202, “Viscosity of Asphalts by Vacuum Capillary Viscometer” Standard Speci- fications for Transportation Materials and Methods of Sampling and Testing, 32nd Edition, AASHTO, Washington, DC, 2012. 5. AASHTO, Designation T 49, “Penetration of Bitumi- nous Materials” Standard Specifications for Trans- portation Materials and Methods of Sampling and Testing, 32nd Edition, AASHTO, Washington, DC, 2012. 6. ASTM, Designation D2170, “D2170/D2170M-10 Standard Test Method for Kinematic Viscosity of Asphalts (Bitumens),” Annual Book of ASTM Stan- dards, Volume 04.03, ASTM, West Conshohocken, PA, 2012. 7. ASTM, Designation C670, “Standard Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials,” ASTM Stan- dards on Precision and Bias for Various Applica- tions, Fifth Edition, ASTM, West Conshohocken, PA, 1997. 8. ASTM, Designation D2171, “Standard Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials,” Annual Book of ASTM Standards, Volume 04.03, ASTM, West Conshohocken, PA, 2012. 9. ASTM, Designation D5-06, “Standard Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials,” Annual Book of ASTM Standards, Volume 04.03, ASTM, West Conshohocken, PA, 2012. UnPUBLIsHed APPendIXes The following appendixes are not published herein, but can be found online at http://www.trb.org by searching for NCHRP Project 10-87. The appen- dixes are titled as follows: Appendix A—New Analysis Method for Pre- paring Precision Estimates Using Proficiency Data Appendix B—Proficiency Sample Instructions and Data Sheets Appendix C—Graphs of T 201 Proficiency Sample Data Appendix D—Graphs of T 202 Proficiency Sam- ple Data Appendix E—Graphs of T 49 Proficiency Sample Data APPendIX F—PReCIsIon stAteMent FoR AAsHto t 201 Kinematic Viscosity of Asphalts (Bitumens) X. Precision and Bias X.1. Precision. Criteria for judging the acceptability of kinematic viscosity of asphalt are given in Table X. NOTE—The figures given in Column 2 are the coefficients of variation that have been found to be appropriate for the materials and conditions of test described in Column 1. The figures in Column 3 are the limits that should not be exceeded by the difference between the results of two properly con- ducted tests. X.2. Bias. No information can be presented on the bias of the procedure because no comparison with the material having an accepted reference value was conducted.

19 APPendIX G—PReCIsIon stAteMent FoR AAsHto t 202 Viscosity of Asphalts by Vacuum Capillary Viscometer X. Precision and Bias X.1. Precision. Criteria for judging the accept- ability of kinematic viscosity of asphalt are given in Table X. NOTE—The figures given in Column 2 are the coefficients of variation that have been found to be appropriate for the materials and conditions of test described in Column 1. The figures in Column 3 are the limits that should not be exceeded by the difference between the results of two properly con- ducted tests. table X Precision estimates of kinematic viscosity of asphalts (bitumens). Condition of Test and Test Property Coefficient of Variation (percent of mean) 1s%a Acceptable Range of Two Test Results (percent of mean) d2s%a Single-operator precision: Original 1.3 3.8 RTFO (average of kinematic viscosity < 850 mm2/s) 1.5 4.2 RTFO (average of kinematic viscosity ≥ 850 mm2/s) 2.7 7.6 Multilaboratory precision: Original 2.3 6.6 RTFO (average of kinematic viscosity < 850 mm2/s) 3.3 9.2 RTFO (average of kinematic viscosity ≥ 850 mm2/s) 5.1 14.4 aThese values represent the 1s% and d2s% limits described in ASTM Practice C670. Note: The precision estimates given in Table X are based on the analysis of test results from 21 pairs of AMRL VGAC proficiency samples. The data analyzed consisted of results from 75 to 118 laboratories for each of the pairs of samples. The analysis included asphalt cements with the average kinematic viscosity of 283 mm2/s to 702 mm2/s for the original asphalt and 429 mm2/s to 1,036 mm2/s for the RTFO residue. table X Precision estimates of viscosity of asphalts by vacuum capillary viscometer. Condition of Test and Test Property Coefficient of Variation (percent of mean) 1s%a Acceptable Range of Two Test Results (percent of mean) d2s%a Single-operator precision: Original 1.5 4.2 RTFO 2.7 7.7 Multilaboratory precision: Original 3.1 8.8 RTFO 6.8 19.2 aThese values represent the 1s% and d2s% limits described in ASTM Practice C670. Note: The precision estimates given in Table X are based on the analysis of test results from 21 pairs of AMRL VGAC proficiency samples. The data analyzed consisted of results from 94 to 135 laboratories for each of the pairs of samples. The analysis included asphalt cements with the average viscosity by vacuum capillary in a range of 102 Pa.s to 5,930 Pa.s for the original asphalt and 403 Pa.s to 11,585 Pa.s for the RTFO residue. X.2. Bias. No information can be presented on the bias of the procedure because no comparison with the material having an accepted reference value was conducted. APPendIX H—PReCIsIon stAteMent FoR AAsHto t 49 Penetration of Bituminous Materials X. Precision and Bias X.1. Precision. Criteria for judging the acceptability of Penetration of Bituminous Materials are given in Table X. NOTE—The figures given in Column 2 are the standard deviations that have been found to be appro priate for the materials and conditions of test described in Column 1. The figures in Column 3 are the limits that should not be exceeded by the difference between the results of two properly con- ducted tests. X.2. Bias. No information can be presented on the bias of the procedure because no comparison with the material having an accepted reference value was conducted.

20 table X Precision estimates of penetration of bituminous materials. Condition of Test and Test Property Standard Deviation 1sa,b Acceptable Range of Two Test Results d2sa,b Single-operator precision: 4°C Original 1s = 0.01X + 0.8 1s = (0.01X + 0.8) × 2.83 RTFO 1s = 0.02X + 0.4 1s = (0.03X + 0.3) × 2.83 25°C Original 1s = 0.01X + 0.7 1s = (0.01X + 0.6) × 2.83 RTFO 1s = 0.01X + 0.5 1s = (0.02X + 0.5) × 2.83 Multilaboratory precision: 4°C Original 1s = 0.06X + 1.9 1s = (0.06X + 2.0) × 2.83 RTFO 1s = 0.06X + 1.5 1s = (0.07X + 1.5) × 2.83 25°C Original 1s = 0.03X + 1.3 1s = (0.02X + 1.8) × 2.83 RTFO 1s = 0.04X + 1.2 1s = (0.04X + 1.2) × 2.83 aThese values represent the 1s and d2s limits described in ASTM Practice C670. bThe value of X represents the average value of two test results. Note: The precision estimates given in Table X are based on the analysis of test results from 21 pairs of AMRL VGAC proficiency samples. The data analyzed consisted of results from 71 to 97 laboratories for each of the pairs of samples. The analysis included original asphalt cements with the average penetration value of 11.7 units to 44 units at 4°C and 33.4 units to 128.9 units at 25°C and RTFO residue with the average penetration value of 7.8 units to 27.2 units at 4°C and 19.8 units to 68.4 units at 25°C.

Transportation Research Board 500 Fifth Street, NW Washington, DC 20001 These digests are issued in order to increase awareness of research results emanating from projects in the Cooperative Research Programs (CRP). Persons wanting to pursue the project subject matter in greater depth should contact the CRP Staff, Transportation Research Board of the National Academies, 500 Fifth Street, NW, Washington, DC 20001. COPYRIGHT INFORMATION Authors herein are responsible for the authenticity of their materials and for obtaining written permissions from publishers or persons who own the copyright to any previously published or copyrighted material used herein. Cooperative Research Programs (CRP) grants permission to reproduce material in this publication for classroom and not-for-profit purposes. Permission is given with the understanding that none of the material will be used to imply TRB, AASHTO, FAA, FHWA, FMCSA, FTA, or Transit Development Corporation endorsement of a particular product, method, or practice. It is expected that those reproducing the material in this document for educational and not-for-profit uses will give appropriate acknowledgment of the source of any reprinted or reproduced material. For other uses of the material, request permission from CRP. ISBN 978-0-309-28394-6 9 780309 283946 9 0 0 0 0 Subscriber Categories: Materials

Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49 Get This Book
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TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 388: Precision Estimates of AASHTO T 201, AASHTO T 202, and AASHTO T 49 presents new, updated precision statements for three asphalt binder test methods. The new methods are based on the analysis of 168 proficiency data sets.

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