Verification of Mechanistic Prediction Models for Asphalt Mixes

This research project evaluates existing mechanistic models that predict permanent deformation (rutting) in asphalt mixes by comparing computer-simulated permanent deformation to that measured in a full-scale accelerated pavement test. Six pavement sections were constructed in the Civil Infrastructure Systems Laboratory (CISL) of Kansas State University with six different asphalt mixes. The sections were loaded with up to 700,000 repetitions of a 89.8 kN(22,000lb) single axle load. The transverse profiles at the pavement surface were measured periodically. For material characterization, asphalt mix samples fabricated in the laboratory were subjected to dynamic modulus (|E*|), static creep - flow time (F_t), dynamic creep - flow number (F_n), triaxial and uniaxial strength tests. The finite element software Abaqus was used to simulate and evaluate three permanent deformation prediction models: creep, elasto-visco-plastic, and Drucker-Prager. The predicted permanent deformation was then compared to permanent deformation measured in CISL for the six asphalt pavement sections. It was found that, with some improvements, creep and elasto-visco-plastic models could be used to predict permanent deformation in asphalt mixes, while the Drucker-Prager model, with hardening criteria, over-predicts permanent deformation.