Reliable and repeatable laboratory testing of hot-mix asphalt (HMA) mixes is of paramount importance to ensure proper HMA mix-design characterization and ultimately to ensure satisfactory field performance. The study reported in this paper was undertaken to evaluate the comparability, repeatability, and reliability of two testing systems, namely, the asphalt mixture performance tester (AMPT) and the traditional universal testing machine (UTM), and to assess if the two systems could be used concurrently or in lieu of one another for dynamic modulus, flow number, and repeated load permanent deformation (RLPD) testing. For the HMA mixes evaluated to accomplish these objectives, the test results from the AMPT and UTMon the basis of dynamic modulus, flow number, and RLPD testingwere statistically comparable and acceptable at the 95% confidence level. The test repeatability and variability in the AMPT and UTM systems also were statistically acceptable with low coefficient of variation values in the test results. Thus either system could be used confidently in lieu of the other to generate results of similar quality and reliability and with a comparable statistical degree of accuracy with acceptable variability for dynamic modulus, flow number, and RLPD testing. The choice or preference is up to the user, given that each system has its own merits and demerits. However, operator and technician proficiency and equipment calibration are some of the most critical factors never to ignore in laboratory testing work of this nature.
