Rheology of polyacrylate binders produced via catalytic chain transfer polymerization as an alternative to bitumen in road pavement materials

Bitumen is a complex, viscoelastic material extracted from the hard-end of the hydrocarbon spectrum during the distillation of crude oil and used as the binder in flexible, asphalt road pavements. Its chemical complexity results in a wide range of physical and rheological properties, which are temperature and time dependent as well as being affected by processes such as oxidative ageing. This paper demonstrates the potential to æengineerÆ the rheological characteristics of binders in asphalt mixtures through the production of polyacrylate binders/adhesives through catalytic chain transfer polymerization (CCTP). The results show that it is possible to produce a range of synthetic polyacrylates with different rheological responses by altering the reactant type, reactant concentration and polymerization conditions to match the rheological properties of road bitumens. An examination of the rheological properties of the binders showed that the key material property that influenced the performance of the polyacrylates was glass transition temperature rather than molecular weight. These findings suggest that such sustainably sourced polyacrylate binders may allow for a move from petrochemical feed stocks to be made and allow for targeted road pavement design based on local climates, offering improved mechanical robustness.