Evaluation of Polymer Modifications Effect on Mix Cracking

Asphalt pavement cracking has become the primary concern in relation to pavement durability over the past several years. The asphalt binder’s contribution to cracking has been investigated as one of the causes for this increase in overall pavement cracking. The increase in cracking has been attributed to the addition of recycled engine oil, air blowing, and various other refining processing techniques. One binder property gaining interest, in the industry, as an indicator of the binders cracking potential is delta critical temperature (ΔTc). Several studies have shown that as the value of ΔTc becomes more negative pavement cracking increases. A significant issue with ΔTc is even when a binder with good ΔTc properties is modified with polymers it has a negative effect on the ΔTc. Given that polymers have been shown to improve cracking response in an asphalt pavement, it becomes critical that resolving this difference in response has to be evaluated. This study is looking at the cracking properties of an asphalt mixture produced with binders having both good and bad ΔTc properties and different levels of polymer modification. Repeated load uniaxial testing and viscoelastic continuum damage analysis was used to evaluate the mixes. The preliminary indications are that polymers can mitigate the poor ΔTc properties of the base asphalt binder.