Atlantic Canadian highways are vulnerable to impacts of climate change, including more frequent cycles of both wetting and drying, and freezing and thawing. These climate impacts coupled with continued increases in truck traffic can cause more severe and premature permanent deformation at high service temperature, fatigue and thermal cracking at low service temperatures, surface wear resistance, and ageing of the pavement. Such negative impacts can be mitigated with changes to the binder. However, replacing a local binder with a different imported binder can increase construction costs and cause supply problems. Alternatively, modifying agents can be used to adjust binder properties as required, but can also cause an increase in construction costs mainly due to their high cost and the need for highly specialized production techniques. The objective of this research project was to investigate the feasibility of utilizing underutilized household and packaging recycled plastics, that are generated in Atlantic Canada, as more cost effective alternatives or as co-modifiers to displace the amount of virgin modifiers used in hot mix asphalt application. The research study entailed analyzing physical characteristics of an array of modified binders and hot mix asphalt mixtures containing recycled low-density polyethylene, recycled polystyrene and the typical engineered virgin modifier (styrene-butadiene-styrene). The analysis included tests used commonly in pavement engineering to evaluate binders and asphalt mixtures. Results of this study suggests that these recycled plastics can be successfully utilized in asphalt binder as modifiers to enhance the functional properties of the mixture and reduce construction costs, thus creating an engineered value-added application of these underutilized resources as opposed to a disposal mechanism.

This thesis deals with the modification of asphalt binder 50/70 with fast reacting SBS. This is a relatively new additive that should be able to improve the binder properties during mixing of the asphalt mix at the plant. In the theoretical part, the issue of asphalt-mixing plant and polymer modification additives is presented. Furthermore, the test methods used such as needle penetration, softening point, determination of the elastic recovery, DSR and MSCR are described. Several modified binder samples were developed for the tests, in which mixing temperature, mixing time and SBS content were combined. The results of each test were compared and evaluated at the end of the thesis.