The team at Asphalt Testing Solutions & Engineering (ATS) recently completed a research study comparing multiple recycling agents, warm mix additives and soft PG binders. Tanya Nash will present the team’s findings at the annual AAPT Conference in Nashville, TN. The presentation is the Evaluation of Recycling Agents – A Contractor’s Point of View on Tuesday, August 31st.
Over the past twenty years asphalt production and construction have become more sophisticated as the industry adopts new products and implements new technologies to achieve better performance. How do contractors evaluate these innovations? How do suppliers present their products in a concise and uniform manner to make it easy for the user to try?
The purpose of this study is to highlight a contractor’s point of view when evaluating technologies to help meet a required rutting and cracking performance. These technologies include recycling agents, soft PG binders and warm mix additives. The ATS team provided each supplier:
- RAP percentage
- RAP continuous grade
- RAP asphalt content
- Continuous grade of the base binder (PG 67-22)
- Optimum asphalt content (OAC) of control mixture
With this data, the suppliers calculated an initial dosage rate for their respective products.
All the dosage rates were converted to percent by weight of virgin binder (bwvb) for consistent sample creation. The ATS team evaluated each product at the volumetric OAC and tested by Hamburg Wheel Tracking (HWT) (AASHTO T 324), the Illinois Flexibility Index (I-FIT) (AASHTO TP 124) and the IDEAL-CT (ASTM D8225). After analyzing the results and ranking the products by dosage efficiency, ATS technicians further evaluated the top performing three products using performance curves at a total of four asphalt binder contents. The performance optimum asphalt content (POAC) was then analyzed for production practicality.
Overall, the importance of common language for dosage from the supplier is very important as well as practical application at POAC. Attend Tanya’s presentation to take a deeper look into this study and product comparison!