Rheological Properties and 2S2P1D Modeling of Seven Bituminous Mixtures with Different Brazilian Bitumens

The characterization of the linear viscoelastic behavior of bituminous mixtures is imperative to analyze and design pavements. The objective of this research is to evaluate the rheological behavior of bituminous mixtures originated from seven different modified and conventional bitumens, representing the Brazilian production. In order to develop the knowledge about the influence of the bitumens on the bituminous mixtures properties, it is essential to know the stiffness of the bituminous mixture when subjected to different loads, temperatures and loading frequencies. The influence of these bitumens on the stiffness of the bituminous mixtures was measured in the compression complex modulus test. From the experimental results, the 2S2P1D modeling was performed by the calibration of seven elements, which consider the mechanical analog of 2 Springs, 2 Parabolic elements, 1 Dashpot and the constants C1 and C2 of time-temperature superposition. The seven bituminous mixtures were produced with the same aggregates according to the grain size distribution “C” of DNIT/BR and were designed by the Superpave methodology with 5 conventional and 2 modified bitumens: four 50/70 penetration bitumens from different Brazilian regions, one 30/45 penetration bitumen, one rubber-modified bitumen, and one SBS polymer modified bitumen. The mathematical modeling allows continuous spectrum analysis in the isotherms, isochronous, Black and Cole-cole diagrams and master curves of norm of complex modulus and phase angle, which is possible evaluate the viscoelastic linear behavior over a wider range of frequencies and temperatures than the experimentally employed. It was verified that all the mixtures had similar values of the constants E₀ (glassy modulus) and E₀₀ (static modulus), however, they were not identical as expected, reinforcing the influence of the different bitumens. In general, the mixtures presented different behaviors in terms of stiffness.