Is low-temperature creep of asphalt mastic independent of filler shape and mineralogy? Arguments from multiscale analysis

This paper focuses on the effect of filler on the low-temperature creep of asphalt mastic. Based on experimental results obtained from bending-beam rheometer (BBR) experiments for both pure bitumen and mastic characterized by different filler types and content, a recently proposed multiscale model is employed for the prediction of low-temperature creep properties of the bitumen-filler composite. Accounting for the distinct matrix-inclusion morphology present at the so-called mastic-scale, the Mori-Tanaka scheme is employed for homogenization. This homogenization scheme is applied to the, bitumen-filler composite, giving insight into the effect of filler on the low-temperature behavior of mastic. Hereby, the filler particles are considered as rigid inclusions with spherical shape, resulting in excellent agreement between the creep parameters of the homogenized material and the respective experimental BBR results. This agreement indicates that only the volume fraction of the filler, entering the Mori-Tanaka scheme, and neither the filler geometry nor the chemical composition of the filler influence low-temperature creep of asphalt mastic.