Thin Bonded Concrete Overlays in Illinois: Preliminary Report on Performance

Abstract

In recent years, two bonded concrete overlays (BCO) were constructed in Illinois. The first was constructed in 1994-1995 on a section of Interstate 80 (I-80) east of Moline. The second BCO was placed in 1996 on a section of Interstate 88 (I-88) further east of Moline. Both the I-80 and the I-88 BCO sections were placed on 203-mm (8-in.) thick continuously reinforced concrete pavements. The I-80 BCO was designed as a 102-mm (4-in.) thick plain concrete overlay. It includes six experimental sections with various percentages of microsilica added to the standard mix design and different bonding agents between the original pavement and the BCO. The I-88 BCO was designed as a 76-mm (3-in.) thick plain concrete overlay. It includes two experimental sections involving different surface preparation methods before BCO placement. Performance of the BCO to date is summarized. Visual distress surveys were conducted annually on selected test sections of the I-80 and I-88 overlays. The I-80 and I-88 overlays were also tested annually for international roughness index values. Condition rating surveys were conducted every 2 years on I-80 and I-88 to define the overall condition of the pavement. The results of the tests and surveys are included. Significant differences have been observed in the performance of the I-80 and I-88 BCO. Although the I-88 BCO has been performing very well, the I-80 BCO, particularly the overlay in the eastbound direction, needed rehabilitation only a few years after construction.