Mechanical Behavior of Polymer-Modified Bituminous Mastics. II: Numerical Approach

Abstract

After a comprehensive experimental program on asphalt mastic modified with styrene-butadiene-styrene (SBS) and polyphosphoric acid (PPA) with two filling ratios of 18% and 35%, in this paper, a biphasic finite-element method was implemented to simulate asphalt mastic as a heterogeneous medium consisting of aggregate particles as inclusions within the asphalt binder as the matrix. For this purpose, linear viscoelastic properties of neat and modified asphalt binders including complex shear modulus (G*) and phase angle (δ) were obtained from the results of dynamic shear rheometer tests in frequency sweep mode, and the generalized Maxwell model was used to prepare material properties for inputting in ABAQUS, which was used to solve the problem numerically. In this research, the structure of aggregate particles was randomly generated, thanks to the custom software MOA (French acronym for random object modeler), based on the aggregate’s grading curve. Comparing the results of numerical modeling with experimental test results showed that, for a filling ratio of 18% by volume, random generation of inclusions can successfully simulate linear viscoelastic behavior of original and modified asphalt mastic. However, with respect to the higher difference between numerical results and experimental observation of asphalt mastic samples with a filling ratio of 35%, a phenomenon known as stiffening effect was captured by using optical microscope pictures and simulated in a numerical model, which positively eliminated the error of numerical modeling.