High-temperature rheological properties and thermo-oxidative aging behavior of organo-montmorillonite/sugarcane bagasse fibre composite-modified asphalt binders

Organo-montmorillonite (OMMT) and sugarcane bagasse fiber (SBF) provide nanosheet barrier and fiber reinforcement, respectively, yet their combined effects on high-temperature rheology, creep recovery, and aging sensitivity remain unclear. Single- and OMMT/SBF composite-modified asphalt binders with varied modifier contents were evaluated by DSR, MSCR, and FTIR under unaged, short-term-aged, and long-term-aged conditions for high-temperature rheology, rutting and creep recovery, aged rheological properties, and functional-group changes. Both modifiers improved viscoelastic response at high temperature and low frequency, with SBF more strongly increasing G* and reducing δ; M0S3 (MxSy denotes x wt.% OMMT and y wt.% SBF) reached average G* and δ values of 440.92 Pa and 47.51°, respectively. M4S3 reached 587.46 Pa, 3.01 times that of the base binder. Composite modification was ratio-dependent: M1S3, M2S3, M3S3, and M4S2 showed relatively higher G*/sinδ within their OMMT-content series, indicating that simply increasing both modifiers did not maximize high-temperature performance. Under high stress, Jnr distinguished permanent deformation resistance better than R. FTIR showed no new characteristic peaks or obvious shifts, indicating no new dominant FTIR-detectable chemical structures and supporting a modification mechanism dominated by physical incorporation and interactions.