Identifying the rheological properties of polymer-modified bitumen based on its morphology

This paper is an attempt to identify the relationship between morphology and performance of polymer-modified bitumen (PmB) containing styrene–butadiene–styrene (SBS) copolymer and carbon nanotubes (CNTs). Morphology is defined as the partition of polymer-rich and bitumen-rich phases, which is obtained by fluorescence microscopy and atomic force microscopy. Rheological properties of PmB are captured by Master curve, Han curve, and Cole–Cole curve. Three different bitumen samples with same polymer amount were selected in this paper. The results showed that a dense network and the interlocked structure in SBS phase provided a better anti-rutting property of PmB. Han curve demonstrated that the elastic modulus improvement of PmB had a close relationship with the size of SBS phase. Cole–Cole curve illustrated that the smaller size and interlocked structure of SBS phase prevented the movement of SBS phase and presented a higher loss viscosity at low-driving speed condition. Furthermore, CNTs played a positive role on the anti-aging property, storage stability, and anti-cracking performance of SBS-modified bitumen.