Evaluation of international roughness index for asphalt overlays placed over cracked and seated concrete pavements

Crack, seat and overlay (CSO) is a rehabilitation technique that has been used on jointed plain concrete pavements. Only a few studies have evaluated the surface roughness of pavement sections rehabilitated using this technique. The purpose of this paper was to evaluate the roughness of roadway sections rehabilitated employing the CSO technique. The data extracted from the long-term pavement performance database were separated based on the weather region and analysed. Then, international roughness index (IRI) prediction models were developed. A separate model was developed for pavement sections in California. For sections with bound bases, thick overlays provide a smoother surface (lower IRI). However, the effect of the overlay thickness on the IRI for sections with unbound bases does not appear to be considerable. Prediction models developed in this study are shown to provide adequate predictive capabilities. Sections in California have initial IRI values that are lower than those found for sections in the wet-with-freeze (WF) and wet-with-no-freeze (WNF) regions. However, California sections are predicted to develop higher IRI values over time, when compared to those sections in the WF and WNF regions.