Optimizing Percentages of Asphalt Content Extracted from Mixes Containing RAP and/or RAS

Abstract

Extracting asphalt binders (ABs) from mixes including recycled asphalt shingles and/or reclaimed asphalt pavement (RAP) needs more investigation. The most popular way for extracting ABs from mixes is centrifuge extraction. The fine materials (dust) extracted with the effluent were quantified using ashing and centrifuge mineral matter determination methods (MMDMs). MMDM could underestimate the extracted asphalt content (EAC)% by overestimating dust amounts. As a result, the actual asphalt content% values were compared to the EAC% values utilizing ashing and centrifuge MMDMs. The EAC% values using the centrifuge MMDM showed more accurate values when compared to the EAC% values using the ashing MMDM. The fabrication techniques used in the field, lab, and plant mixes and the additives used in these mixes altered the interaction processes between virgin asphalt binders (VABs) and RAP binders. More interactions occurred in the plant mixes due to reheating these mixes prior to compaction in the lab. Thus, the EAC% values from plant mixes were higher than the EAC% values from the same mixes obtained from the field. The interactions between the RAP binder and the VAB were boosted by Evoflex that increased the EAC% values.