Mechanistic Analyses of FHWA's Accelerated Loading Facility Pavements: Primary Response

In-depth details are provided for mechanistic analyses conducted for the asphalt pavements of the FHWA accelerated loading facility (ALF) by using available programs, including KENPAVE, WINLEA, EVERSTRS, EVERFLEX, and VESYS 5W. These pavements were constructed by using highly modified and unmodified asphalt binders. The described analyses focused on primary response under the ALF pavements. This study included multilayer elastic theory (MLET) solutions, finite element analysis, and analysis using the VESYS 5W program. Predictions of the primary response for the fatigue mode included the horizontal tensile stress and strain at the bottom of the hot-mix asphalt (HMA) layer and for the rutting mode included the vertical compressive stress and strain on top of each pavement layer. The impact of loading frequency and stress sensitivity (nonlinearity) on fatigue primary response, rutting primary response, and principal stresses was investigated. The frequency did affect the fatigue tensile stress and strain, primarily at the bottom of the HMA layer. It also affected the major and minor principal stresses, particularly at the bottom of the HMA layer. The frequency effect on the rutting compressive stress was insignificant, whereas it was considerable for the compressive strain within the HMA layer. The MLET solutions that used a linear elastic base provided reasonable predictions for the measured tensile strains for highly modified and unmodified asphalt pavements with an absolute percentage error in the range of 0% to 15% percent in most cases. The solutions of the MLET and VESYS 5W programs were capable of providing good predictions of the vertical deformation within the HMA layer that correlated well with the measured permanent deformation values.