Optimisation of the regeneration parameters of colza oil residue regenerated SBS modified bitumen using response surface methodology and its multiscale characterisation

In this study, response surface methodology (RSM) was used to optimise the design and predict the physical properties of colza oil residue (COR) regenerated SBS modified bitumen based on regeneration preparation parameters and COR content. A total of 27 experiments were conducted using the Box–Behnken design, and a quadratic regression model was applied to evaluate all responses under the global optimal conditions. Numerical optimisation determined the optimal regeneration design for SBS modified bitumen, including a shear time of 17.7 min, a shear temperature of 150°C, a shear speed of 1050 rpm, and a maximum COR content of 8%, achieving a comprehensive desirability of 69.2%. COR can not only restore the flexibility of bitumen, but also improve its heat recovery ability at low temperatures. Moreover, COR improves the flowability of bitumen by introducing fatty acid esters, but does not trigger significant chemical reactions.