01687983

Component

http://www.trb.org/Main/Blurbs/178401.aspx

Generally, four approaches have been utilized to address the potentially premature cracking issue of recycled asphalt pavement (RAP)–recycled asphalt shingles (RAS) mixes: (1) limiting RAP–RAS usage; many states departments of transportation in the United States set an upper limit for RAP–RAS usage, such as maximum allowable binder replacement of say for example 20% for surface mixes; (2) using soft virgin binders especially on the low temperature grade (i.e., PG XX-28, PG XX-34); (3) increasing design density (lowering design air voids) or reducing Ndesign; and (4) rejuvenating RAP–RAS binder with recycling agents (or rejuvenators) in the mix design process. The Texas DOT (TxDOT) has implemented the first three approaches in its new asphalt mix specifications. In last several years, TxDOT has been working the Texas A&M Transportation Institute (TTI) to investigate the best use of recycling agents to improve RAP–RAS mixes performance. This paper presents the work and findings from the research done at TTI. The characteristics of RAP, RAS, and recycling agents are discussed first, followed by the characteristics of their blends. This paper also presents the balanced mix design (BMD) method for mixes containing RAP–RAS–recycling agent. To demonstrate the proposed BMD, a field project designed with the BMD with RAP–RAS–recycling agent is described. Finally, a summary and conclusions are presented at the end of this paper.

01685369

English

pp 44-59

2018-10

Transportation Research Circular

Digital/other

Figures; References; Tables

Asphalt mixtures; Mix design; Reclaimed asphalt pavements; Recycled materials; Shingles

Texas

Highways; Materials; Pavements

TRIS, TRB, ATRI

Nov 27 2018 10:48AM

• Application of Performance Tests During Asphalt Mixture Design: Louisiana’s Approach
• Development and Implementation of the Illinois Flexibility Index Test: A Protocol to Evaluate the Cracking Resistance of Asphalt Mixtures
• Evaluating Balanced Mixture Design for New Jersey to Enhance Asphalt Mixture Durability
• Mixture Design for Better Field Compaction
• Optimized Mix Design Approach: Contractor’s Perspective