Evaluation of Long-Term Pavement Performance Based on New Mexico LTPP SPS5 Data

The Long Term Pavement Performance (LTPP) program has Specific Pavement Studies 5 (SPS-5), which study the effects of overlay rehabilitation on typical distresses. Each SPS-5sites has eight sections with two overlay thicknesses (50 mm and 125 mm), two overlay types (virgin asphalt mix and 30% recycled asphalt (RAP) mix), and Surface preparation prior to rehabilitation ( milling or not milling). The New Mexico SPS-5 sections are constructed in the eastbound Interstate-10 (I-10) in 1995. In this study, five distress parameters from these test sections are analyzed including International Roughness Index (IRI), rutting, fatigue cracking, longitudinal cracking, and transverse cracking. Analyses are conducted to determine which overlay factors affected the pavement performance more. Also statistical analysis is conducted to compare the performance of the No RAP and RAP mix. Analysis show that overlay age has the strongest impact on the overall pavement performance. Overlays with RAP showed more distresses and roughness than the no RAP overlays, although this difference is not significant for rutting and IRI. Also thick overlays perform better than the thin overlays except for rutting. Milling prior to the rehabilitation decreases IRI and transverse cracking, but do not have any effect on longitudinal cracking.