ABSTRACT
The recycling and reuse of bituminous materials is not a recent development, the first asphalt pavement recycling project being recorded in 1915. Recycled asphalt pavement (RAP) material consists of aggregate and bitumen that has been removed and/or reprocessed from an asphalt pavement. In situ recycling is also known as in-place recycling. Hot in situ asphalt recycling is used to transform an aged and partially failed asphalt surface layer into a good-as-new product. In-plant recycling involves the stockpiling RAP at the asphalt plant before mixing with virgin material to produce a new asphalt mixture. In the hot recycling process, RAP material is blended with superheated virgin aggregate before mixing with virgin bitumen. The gradation of RAP is quite different from the gradation of the original asphalt mixture since it consists of agglomerates rather than individual particles, and the key difference is a much reduced fines content. This material variability needs to be considered when designing recycled asphalt mixtures.
