Optimizing The Effective Use Of Rap In Local Roadways

This report summarizes the research work that was completed to assess the optimum percentages of recycled asphalt pavement (RAP) that can be used in surface course mixtures of local roadways while ensuring durability is maintained. This project was divided into two phases. Phase 1 included conducting a comprehensive laboratory testing on mixtures with different RAP contents and recycling agents. Based on the results of Phase 1, Phase 2 of this project involved constructing eight test sections as a part of a resurfacing project on Hall Road in the City of Columbus. Surface course asphalt mixtures with a similar aggregate blend but different percentages of RAP were used in these test sections. The first section (control section) had a mix with 20% RAP and PG 64-22 binder. While three test sections had mixes with 30%, 40%, 50% RAP, PG 64-22 binder, and Sylvaroad recycling agent, three other sections had mixes with the same RAP percentages and binder but used Hydrolene as the recycling agent. Finally, the last section was constructed using a mixture containing 30% RAP and PG 64-28 binder with no recycling agent. Cores were obtained at different locations within each test section. In addition, specimens were compacted in a laboratory from loose mixtures that were obtained during the construction of each test section. Tests were done on field cores and laboratory-compacted specimens. The test results showed that Hydrolene was more effective than Sylvaroad in improving the fatigue cracking resistance of RAP mixes with more than 0.3 binder. In addition, the tests results showed that the 30% RAP, 40% RAP, and 50% RAP mixes had similar low-temperature cracking resistance to that of the control. The laboratory test results also showed that all mixes had acceptable rutting resistance. The results of the cost analyses conducted in Phase 2 indicated that using a higher RAP content of 40% and recycling agents can reduce the initial cost of an asphalt mixture by at least 15%.