Development of Heavy-Duty Mastic Asphalt Bridge Surfacing, Incorporating Trinidad Lake Asphalt and Polymer Modified Binders

ABSTRACT The mechanical properties of mastic asphalt are highly affected by the rheological properties of the respective mastic binder. Trinidad Lake Asphalt (TLA), which comprises naturally weathered bitumen and filler, is often used for modifying the mastic binder properties in order to obtain improved performance of the respective mastic asphalt mixture (such as stiffness and deformation resistance). Increased traffic loading and severe environmental conditions often demand more stringent requirements for the mixture performance; in these cases, further modifications of the mastic binder by polymer modification may be required. This paper demonstrates the potential use of polymer modified binders for mastic asphalt bridge surfacing for enhancing the mixture performance for use under more severe environmental conditions and/or to carry increased traffic loading. Rheological analysis showed that the “stiffening” effect caused by addition of TLA into mastic binder, which is normally anticipated in the case of conventional mastic asphalt (incorporating unmodified bitumen), took place in a different way if a polymer modifier was also used. Changes in rheological properties of different mastic binders were also reflected by changes in performance (such as low temperature strength, stiffness and deformation resistance) of their respective mastic asphalt mixtures.