AASHTO T 308, Determining the Asphalt Binder Content of Hot Mix Asphalt (HMA) by the Ignition Method,¡¨ requires determination of asphalt and aggregate correction factors for asphalt mix designs for each ignition furnace used to test a design. In some cases where there are numerous asphalt mix designs or numerous ignition furnaces testing a particular mix design, correction factors are shared between ignition furnaces, though this practice is not permitted by AASHTO T 308 without supporting evidence.
There is a lack of knowledge of (1) how ignition furnace installation, operation, and maintenance influence correction factors and (2) ways to minimize differences that arise between ignition furnaces. Moreover, there is a lack of a statistically valid verification procedure to identify causes for non-comparing, statistically different, or biased test results from ignition furnaces. A verification procedure will promote consistency in results and assist in dispute resolution.
The objectives of this research were to (1) determine the variability of asphalt and aggregate correction factors for asphalt mixes containing significant asphalt recycled materials compared to those with virgin binder and aggregate only; (2) further evaluate the effect of reducing the test temperature of AASHTO T 308 method to 800¢XF; and (3) conduct an interlaboratory study with different mixes to establish a new precision statement for the test procedure.
STATUS: Available as NCHRP Research Report 1060 here: https://www.trb.org/Main/Blurbs/182982.aspx
