Materials and Pavement Evaluation for the New Doha International Airport Using Mechanistic-Empirical Technology: Fid-Bau Portal

Materials and Pavement Evaluation for the New Doha International Airport Using Mechanistic-Empirical Technology

Leahy, R. B. / Popescu, L. / Dedmon, C. / Monismith, C. L.

The paper discusses the use of mechanistic-empirical analyses to predict the performance of the air-side asphalt concrete pavements at the New Doha International Airport. The materials and pavement layer geometry were designed in accordance with Federal Aviation Administration (FAA) requirements. To check the adequacy of the 75-blow Marshall mix design, moisture sensitivity and permanent deformation testing was conducted. For moisture sensitivity studies, both the AASHTO T-283 (Lottman) and AASHTO T-324 (Hamburg wheel tracking) tests were performed. While the AAHTO T-324 procedure can be used to evaluate the mix in a "wet" or "dry" state, it does not provide a realistic estimate of in situ rutting potential under actual traffic loading. Thus, to estimate the rutting performance of the materials in the pavement section subjected to the design traffic, data from the repeated load simple shear test at constant height (RSST-CH), AASHTO T-320, and mechanistic pavement analyses were utilized. Mixes at the design binder content, i.e., "optimum" and "optimum + 0.5%" were tested in repeated loading at 122°F (50°C). These test results were used in a rut depth estimation procedure developed during the WesTrack accelerated pavement test program conducted from 1995–2000. In this approach calculated stresses and strains within the multilayer elastic system and RSST-CH results are used to estimate rutting in the asphalt-bound layer for the anticipated traffic and site conditions, i.e., pavement temperatures. To accumulate permanent strains resulting from the anticipated aircraft mix, a time-hardening cumulative damage hypothesis was utilized. Results of these analyses suggest that the proposed mix design should provide adequate rutting resistance. However, the results also suggest that the production tolerance for binder content should be limited to ±0.25 percent. Using subgrade strain criteria suggested by Shell researchers, an estimate of rutting contributed by the unbound layers was also determined for the anticipated traffic and site conditions. Results of this analysis indicate that the overall pavement thickness is adequate. A brief description of the rut prediction methodology is included. RSST-CH results were compared to rutting criteria established for San Francisco International Airport subjected to stop-and-go movements of B747-400 aircraft. This comparison supports the conclusion reached from the mechanistic-empirical permanent deformation analyses for the asphalt bound layer.