Abstract
In 2005, the Illinois Tollway staff rehabilitated a 33-mi-long segment of Interstate Highway 88 in Illinois by rubblizing deteriorated jointed plain concrete pavement (JPCP) and placing a hot-mix asphalt (HMA) overlay on the rubblized JPCP. The pavement design called for the ultimate pavement structure to be constructed in two stages: the first at the time of rubblization, when at least 6.0 in. of HMA would be placed, and the second 10 years later, when 2.0 in. of HMA would be cold milled and 6.0 in. of HMA placed back. The pavement design called on the tollway staff’s experience with rubblization and research surrounding the fatigue endurance limit to develop a staged construction strategy. The strategy would reduce up-front construction costs by placing a minimum of 6.0 in. of HMA at initial construction. The tollway staff was confident that the strategy would work, but the pavement performance was monitored annually for verification. Annual monitoring included pavement distress condition surveys, deflection testing and deflection data analysis, and pavement coring. In particular, the tollway staff desired confirmation that the staged construction strategy would yield a perpetual asphalt pavement by controlling the amount of bottom-up fatigue cracking that would develop in the asphalt mat. After 9 years of observations and data analysis, the staff has confirmed the pavement is exhibiting the properties of a perpetual pavement and the staged construction strategy should ultimately prove successful.