A byproduct of changes in bitumen quality is the trend for engineers to formulate asphalt mixes using a balanced mix design approach. This relatively new method accounts for variable bitumen specifications while prioritizing adherence to performance standards. Balanced mix design also allowed for incorporation of additives that can enhance the functional properties of a mix to improve performance outcomes. Rather than relying solely on binder or aggregate specifications to meet performance standards, all aspects of the mix (binder, aggregate, modifiers, and additives) are formulated to balance factors such as fatigue, rutting, and cracking characteristics.
Testing High-RAP Mixes with Asphalt Rejuvenators
The use of reclaimed asphalt and recycled asphalt materials is becoming increasingly widespread. High-RAP mixtures, or those defined as those containing more than 25% RAP by total mix weight, can offer significant environmental and economic benefits by reducing reliance on virgin aggregates and binder. However, increasing RAP content can introduce performance challenges. The aged binder in RAP is typically stiff and brittle, which can negatively impact cracking resistance and long-term durability. [...]
