Field Performance of Continuously Reinforced Concrete Pavement in Illinois

Reviewed are the design and performance of continuously reinforced concrete pavement (CRCP) in Illinois. Illinois has built more than 4267 two-lane km (2,650 mi) of CRCP on the Interstate system since the mid-1950s. CRCP has been constructed on nearly all urban freeways in the Chicago area and has shown excellent performance under severe weather and heavy traffic conditions. The effect of key design and construction parameters on long-term CRCP performance is investigated by using a database based on field surveys conducted from 1977 to 1994 compiled by the Illinois Department of Transportation. Analysis of the data shows the following variables have significant effects on performance: longitudinal reinforcement content (greatest effect of all variables), slab thickness (also very significant), traffic load applications, depth of reinforcement, base type, and D-cracking of concrete. CRCP built with tubes or chairs exhibited overall about the same performance. Experimental field studies in Illinois showed that depth of reinforcement has a large effect on crack width and, eventually, on punchouts. Specifically, the investigation indicated that CRCP sections with a slab 178 mm (7 in.) thick and steel content less than 0.6 percent developed the most structural failures. CRCP sections with a slab 254 mm (10 in.) thick and steel content from 0.7 to 0.8 percent developed the fewest failures. However, all the CRCP sections in this study, regardless of thickness designs and steel content, typically have carried more traffic than they were designed for and have lasted longer than their design traffic life.