Investigation of Stripping in Minnesota Class 7 (RAP) and Full-Depth Reclamation Base Materials

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This research investigates the effect of RAP content, freeze-thaw and severe moisture conditions on the structural capacity of the pavement base layer. The investigated material included one source of 100% RAP, one source of virgin aggregate, and three full depth reclamation samples where RAP was mixed with virgin aggregate/soil and was in use as a base layer. RAP was blended in the lab with the virgin aggregate at 50% and 75% RAP content. RAP was coarser than virgin aggregate and it had a higher percentage loss in the Micro-Deval test. The resilient modulus (MR) was measured following the National Cooperative Highway Research Program 1-28A test protocol. The MR for all RAP material was higher than that of the virgin aggregate. The resilient modulus of RAP material was found to be dependent on confining pressure. There was no clear loss of the modulus due to freeze-thaw conditioning for the tested RAP. Decreasing the moisture content increased the resilient modulus for RAP material. Maximum deviator stress in the shear test was reduced after freeze-thaw (F-T) conditioning for RAP/aggregate blends at a low confining pressure, but the effect of F-T on the maximum deviator stress was not clear at a higher confining pressure.