Precision Estimates for AASHTO Test Method T 105, Determined Using CCRL Proficiency Sample Data

Abstract

Under National Cooperative Highway Research Program (NCHRP) Project 9-26, the AASHTO Materials Reference Laboratory (AMRL) is conducting a multi-phase research project to improve estimates of precision in AASHTO test methods for asphalt binder and hot-mix asphalt (HMA). The report from Phase 1 of Project 9-26 includes precision estimates of selected volumetric properties of HMA using non-absorptive aggregates. The report from Phase 2 discusses the results of an investigation into the cause of variations in HMA bulk specific gravity test results using non-absorptive aggregates. The report from Phase 3 includes a robust technique developed by AMRL for analyzing proficiency sample data for the purpose of obtaining reliable single-operator and multilaboratory estimates of precision. The report from Phase 4 includes two parts. Part one covers the precision estimates of selected volumetric properties of HMA using absorptive aggregates. Part two of the report investigates the effect of aging period on the volumetric properties of the absorptive aggregates. This report includes the results of Phase 5 of NCHRP Project 9-26 where data from the AMRL Proficiency Sample Program (PSP) are used to update precision estimates for AASHTO Standard Test Method T269, “Percent Air Voids in Compacted Dense and Open Asphalt Mixtures.