Modeling shear stress response of bituminous materials under small and large strains

The paper at hand focuses on modeling the stress response of different mastics and asphalt binders exposed to small and large shear strains using Bergström-Boyce (BB) constitutive model as well as Finite Element (FE) approach. In this paper, a set of experiments based on Large Amplitude Oscillatory Shear (LAOS) test were designed and conducted to capture the state of strain dependence of bituminous mastics and binders over a broad spectrum of strain domain (0.5%, 10%, 20%, 30%, and 40%) pertaining linear and nonlinear regimes of such materials. Using the experimental data, the BB constitutive model was utilized to describe the attained behavior at two temperatures (30 °C and 40 °C) and varied strain amplitudes. The material properties derived from the BB model were further implemented into a Finite Element Model (FEM) using the ABAQUS platform to simulate the stress response of bituminous materials for a wide range of strain amplitudes. It has been shown that the bituminous mastics and binders have strong nonlinearity at high strain amplitudes, depicted graphically based on the progressive distortion from the elliptical form of Lissajous-Bowditch (LB) plot. Based on the observed goodness of fitting, the BB model well-described the experimental results for linear and nonlinear behaviors. Using the optimized parameters, it was confirmed that the BB model is well suited to build a numerical model that could reproduce stress responses derived from the LAOS results for a wide range of strain levels. The advantage of the methodology presented herein allows adaptable model constants of the BB model depending on the imposed level of strain and temperature and hence, the FEM can describe both linear and nonlinear behaviors of bituminous mastics and binders. From this paper, researchers can take advantage of capturing the stress response of binders and mastics under small and large strain amplitudes to stimulate the research on better representation of the complex behavior of asphalt mixes based on the role of mastic and asphalt binder