Elasto-Plastic Model for Bitumen Stabilized Materials Using Triaxial Testing and Finite Element Modelling

Cold recycling with BSMs is becoming a very common technique, nevertheless there are minimal constitutive models available that can fully characterize their mechanical response in pavement systems. The aim of this research project was to identify the intrinsic material properties through a finite element simulation of triaxial tests performed in laboratory for BSMs with different mix designs. The main differences between the mechanical behaviors of BSM with respect to foam bitumen content (1.5% and 3%) are determined. All mixes discussed herein contained same active filler amount of 1.5% Portland cement. The triaxial tests were performed on cylindrical specimens at different confining pressures (0, 100, 200 kPa) in a displacement control configuration (3 mm/min). The triaxial tests at the different confining pressures were simulated using a 3D finite element model to determine plasticity parameters. The input values for an elasto-plastic model (Young’s modulus, Poisson’s ratio, cohesion, friction angle and dilatation angle) have been calibrated to match experiment results with simulations, mainly in terms of strain and stress levels corresponding to onset of plastic deformation. The parameters obtained by these simulations are very useful to predict the rutting behavior of bituminous stabilized materials in a multilayer pavement structure. This study provides an insight on how bitumen content affects constitutive BSMs properties.