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APPENDIX E: PRECISION STATEMENT FOR AASHTO T269
E-1 PRECISION STATEMENT FOR AASHTO T269 PERCENT AIR VOIDS IN COMPACTED DENSE AND OPEN ASPHALT MIXTRURES X. Precision and Bias X.1 Precision Criteria for judging the acceptability of percent air voids test results that are obtained using T 166 and T 209 for dense asphalt mixtures using nonporous aggregates are: X.1.1 Single-Operator Precision (Repeatability) â The figures in Column 3 of Table X are the standard deviations that have been found to be appropriate for the compaction method described in Column 1. Two results obtained in the same laboratory, by the same operator using the same equipment, in the shortest practical period of time, should not be considered suspect unless the difference in the two results exceeds the values given in Table X, Column 4. X.1.2 Multilaboratory Precision (Reproducibility) â The figures in Column 3 of Table X are the standard deviations that have been found to be appropriate for the compaction method described in Column 1. Two results submitted by two different operators testing the same material in different laboratories shall not be considered suspect unless the difference in the two results exceeds the values given in Table X, Column 4. Table X â Precision Estimates Compaction Method Specimen Diameter Standard Deviation (1s)a Acceptable Range of Two Test Results (d2s)a Single Operator Precision: AASHTO T245b 4-inch 0.48 1.36 AASHTO T247 4-inch 0.52 1.47 ASTM D4013 4-inch 0.50 1.42 AASHTO T312 6-inch 0.47 1.33 Multilaboratory Precision: AASHTO T245b 4-inch 1.08 3.06 AASHTO T247 4-inch 1.39 3.94 ASTM D4013 4-inch 1.49 4.22 AASHTO T312 6-inch 1.01 2.86 a These values represent the 1s and d2s limits described in ASTM Practice C670. b The results reported for specimens compacted using T245 were determined as the average of three specimens. Note â The precision estimates given in Table X are based on the analysis of test results from three pairs of AMRL proficiency samples. The data analyzed consisted of results from 20 to 578 laboratories for each of the three pairs of samples. The analysis included three binder grades: PG 70-22, PG 64-10, PG 64-22. Average results for air voids ranged from 2.37% to 7.95%. The details of this analysis are in NCHRP Final Report, NCHRP Project No. 9-26, Phase 5. X.2 Bias â No information can be presented on the bias of the procedure because no material having an accepted reference value is available.
