Strain Response of Reclaimed Asphalt Pavement Material Blends under Extended Loading Testing

The use of reclaimed asphalt pavement (RAP) material in new paving projects is increasing in popularity, with research showing that RAP blended with aggregate will increase the resilient modulus of subgrade material. These studies have focused on the effects of RAP on the resilient modulus of the base layer without in-depth observation into the factors affecting permanent deformation. The objective of this research is to examine the early and long-term development of cumulative strain in RAP blends under combinations of moisture content, content of fines, and stress levels. Single stage testing is conducted in the laboratory for sample materials containing aggregate and RAP material. Cumulative strain percentage is the quantity of comparison between materials and testing results. Blends of 50\% RAP and 50\% Class 5 mixed at optimum moisture content (OMC) yield the lowest strain rates in the early testing stages and the lowest long-term accumulated strain. Blends tested with 10\% fines yield comparable results to all OMC blends. Blends with OMC+2\% accumulate more strain than Class 5 blends, whereas mixes with high content of fines and OMC+2\% are the most susceptible to developing strain. Accumulated strain per cycle has the highest rate in the preliminary stages of testing. Over 90\% of the 20,000 cycle accumulated strain occurs at 3,000 to 5,000 cycles for high moisture blends. RAP reduces the effect of strain rate sensitivity and yields a more resilient response capability than Class 5 material.