Fracture characterisation of polymer modified asphalt concrete mixes for applications in diverse climatic regions

Among various types of polymers used as modifiers, Styrene-Butadiene-Styrene (SBS) is the most commonly used as an elastomeric type of polymer to improve the cracking and rutting resistance of asphalt concrete (AC) mixtures. In this study, we explored low and intermediate-temperature fracture characteristics of mixes prepared with binders modified with incrementally increased percentages of SBS. Low and intermediate-temperature fracture experiments were conducted to compare fracture characteristics of modified and unmodified binders. The application of polymer modification is demonstrated using dense-graded and gap-graded stone mastic asphalt (SMA) type gradations. Based on the fracture properties and trends observed, a performance-based AC mixture grading and selection system for different climatic regions is proposed. Fracture energy converged to a baseline value governed by the low-temperature binder grade regardless of the mix type and polymer modification. Polymer modification in fine-graded mixes was shown to remain effective for testing temperatures of −12°C and above for binders with −22 low PG. The concept of critical cracking temperature is introduced to guide the application of polymer modification in different climatic regions. The findings of this research will support agencies in developing binder selection protocols to optimise the cracking resistance of mixes in different climatic regions.