Preliminary study of materials effect of cold in-place and full-depth reclamation asphalt concrete in mechanistic-empirical pavement design

In this study, the materials effect of cold in-place (CIR) and full-depth reclamation (FDR) asphalt materials were investigated for the incorporation into the Mechanistic-Empirical Pavement Design. The Mechanistic-Empirical pavement Design Guide (MEPDG) was implemented in this study, where the pavement response to the interacting effect of materials types, moduli, climate, and traffic conditions were studied. The lab measured material properties such as dynamic modulus and other assumed parameters were used as inputs to the MEPDG software to evaluate the effect of CIR and FDR asphalt materials to pavement design. In the analysis of typical hot mix asphalt (HMA) pavement with 4-inch HMA, 8-inch FDR layer and subgrade, by treating the CIR or FDR layer as Asphalt Concrete (AC) layer, asphalt permeable base, granular base with seasonal resilient modulus (MR) input and granular base with constant MR input, the pavement rutting and fatigue cracking distresses were evaluated. Treating the CIR as AC layer in MEPDG would get the best performance prediction in both rutting and fatigue cracking. Asphalt permeable base turned out to perform better than granular base with seasonal MR input in rutting while showed a higher fatigue cracking than granular base with seasonal MR input. Treating CIR as granular base with constant MR input would get significant higher distresses prediction than other three types, especially for fatigue cracking. This preliminary result demonstrates that the impact of treating CIR as different layer types is significant. Besides, it can be potential evidence that the default MR input of CIR as 20ksi is unreasonable.