Recycled asphalt pavements (RAP) consist of unprocessed (milled) or processed (crushed) asphalt mixtures from roadways or other resources. While RAP is often used in hot/warm mix asphalt inside asphalt plants, on-site use of RAP presents great advantages in lowering costs and expediting construction without the need for hauling. The recycling of RAP is a sustainable practice that could potentially help reduce costs, preserve the environment, and reduce greenhouse gas emissions, provided that the engineering performance of the roadways constructed with RAP is not compromised. Currently, the Illinois Tollway allows RAP to be used in roadway embankments and as structural backfill, as well as for aggregate surfacing. However, the use of RAP in roadway embankments and as structural backfill is loosely specified in terms of maximum size, gradation, engineering properties, and acceptance. On the basis of a literature review, survey, forensic investigation, and laboratory experiments, this project will develop a draft specification that will define the allowable RAP materials to be placed, appropriate construction practices, and field acceptance criteria. The specification will ensure that the RAP embankment or fill will perform as well as other well-performing conventional soils/aggregates, if not better.
Project Investigators:
Haifang Wen
Balasingam Muhunthan
Idil Akin
Civil and Environmental Engineering, WSU
Sponsor: Illinois Tollway
Scheduled completion: June 2021