Evaluating effectiveness of polymerized pellets mix additives on improving asphalt mix properties

Polymer-modified asphalt binders have been used for years to produce asphalt mixes with improved resistance to rutting, fatigue cracking, and thermal cracking. Special equipment and technique, which may not be always available, are required to produce polymer-modified binders with desired engineering properties. Recently, a new approach is introduced to facilitate the use of polymers in asphalt mixtures. Polymerized pellets mix additive, which contains a high amount of Styrene Butadiene Styrene [SBS] and asphalt binder, can be directly incorporated into the mix during production in asphalt plant without the need for any special equipment. Logistically, this new form of mix additive simplifies and expands the use of polymers even for small paving projects. However, due to the novelty of this technology, more research is required to assess its efficacy. In this paper stiffness, rutting, fatigue, and thermal cracking resistance properties of asphalt mix modified with polymerized pellets are compared to the mixes containing unmodified and polymer-modified binders. The effects of long-term oxidative aging on stiffness and strength of mixes were also evaluated. Results of this study showed that the polymerized pellets had similar effects as the SBS polymer-modified binder in improving stiffness, rutting resistance, fatigue cracking resistance, and low temperature cracking resistance of asphalt mixes.