Comparative Evaluation of Performance of Warm Mix RAP Asphalt Under Accelerated Unidirectional Wheelload Trafficking

The paper focuses on testing comparative evaluation of fatigue performance of composite asphalt pavement layers constructed at the Turner-Fairbank Highway Research Center (T-F) under full-scale trafficking with the ALF and the one third scaled MMLS3 (also known as MLS 11, since January 2015) of Virginia Tech in Blacksburg. The goal was to enhance economics of APT testing. Virgin 100 mm asphalt slabs of the composite 50 mm dual layers were extracted from the in situ un-trafficked sections of the test lanes after unidirectional testing with the ALF using a formalized process. The process was developed to overcome constraints due to traffic and temperature control as well as minimizing logistics during field testing. After extraction, the slabs were transported by vehicle to Blacksburg, VA where the MMLS3 testing procedure was formalized by means of a proof test on the lower 50 mm of a slab from Lane 9. For this, a 25 mm neoprene slab was used as interlayer between the asphalt and the underlying in situ concrete floor. After successful completion of the proof test, four further tests were completed. Two were done on the extractions from Lane 9B and 9A, and the other two were done on the extraction from Lane 5. The latter three tests all had two 25 mm neoprene interlayers. Aspects that were considered in the comparative evaluations were rutting, strain response, seismic stiffness using the Portable Seismic Pavement Analyzer (PSPA), cracking and contact stress under the MMLS tire. The effects of the respective material characteristics were also discussed. From the findings it was concluded that the monitored parameters found from the scaled tests were comparable to the related full-scale ALF test results in terms of intrinsic material characteristics and pavement performance. This is similar to earlier reported comparative studies. The authors consider this finding to be an economic benefit that should be utilized in pavement engineering studies.