Mechanical Properties of the Composite Asphalt-Styrene-Butadiene Copolymer at High Degree of Modification

Abstract

The morphology and elastic moduli of the composite styrene-butádiene copolymer-asphalt (SBR-A) were obtained at different degrees of modification from 0 to 40% by weight. Even when the 40% of rubber is far above the usual amount of rubber used for asphalt modification, the purpose of this work is to study the composite morphology at high degree of modification and to obtain a prediction for the elastic response of the material.

The morphology of the samples was obtained by scanning and transmission electron microscopy. The mechanical properties of the samples obtained at different chemical compositions were determined at three different strain rates: 5, 50 and 500 mm/min.

For low SBR concentrations, the elastic modulus of the as prepared materials was well modeled by using the Kerner's model, however for concentrations larger than around 20%, the mechanical response of the material is higher than the predicted by this model. By introducing a percolation model that takes into account the connectivity between the discrete domains of the material, it was possible to obtain a good agreement with the experimental data for SBR concentrations up to 40%.

Key Words:

• Asphalt
• styrene-butadiene copolymers
• mechanical properties