When RAP is used in HMA,

When utilizing Reclaimed Asphalt Pavement (RAP) in Hot Mix Asphalt (HMA), it is crucial to consider several factors that collectively ensure the quality and performance of the final mix. Each of the aspects mentioned corresponds to best practices in the industry.

The first point highlights that the virgin binder grade may need adjustment due to the percentage of RAP included. RAP contains aged asphalt binder, which affects the overall properties of the mix. To accommodate this, engineers might adjust the virgin binder grade to maintain desired performance characteristics, ensuring that the final mixture adheres to specifications for durability, flexibility, and resistance to cracking, which can be altered by the inclusion of RAP.

Stockpiling RAP with respect to dominant particle size is significant because the gradation of the stockpiled material can impact the consistency of the HMA. Material with consistent particle size distribution leads to better handling and mixing characteristics, which can improve the overall performance of the asphalt mix.

Lastly, measuring the asphalt binder content is essential to verify that the mix meets the designed specifications. Understanding the binder composition, including the contribution from RAP, helps in guaranteeing that the final product will perform as required.

Therefore, acknowledging the need to adjust the virgin binder grade, correctly stockpile RAP according to its size