A study of the performance of Continuously Reinforced Concrete Pavement (CRCP) constructed on the Interstate highway system in Illinois has-been conducted. The major purpose is to determine the types, severities, amounts, and causes of distress. This information will then be used to develop optimum maintenance procedures to repair the distress that occurs, and preventative maintenance procedures to reduce the rate of distress occurrence. The distress data collected can also be used to update CRCP design procedures. Approximately 1230 miles of Interstate highway was surveyed, consisting of 7 to 10 in. (17-25 cm) slabs over granular and stabilized subbases. Distress found includes edge punchouts, steel ruptures, "D" cracking, blowups, construction joint failures, lug rotation, longitudinal cracking, distress related to construction problems, pumping, and shoulder deterioration. Heavy truck loads, excess free moisture, deicing salts, construction practice and poor aggregate quality in the CRCP slab are the major factors causing distress. CRCP slab thickness and foundation support have a very significant effect on structural distress development. "D" cracking is causing severe deterioration of several projects. Overall, the performance of the thicker CRCP slabs (i.e., 9-10 in.) has been very good under heavy truck traffic; however, the performance of many sections of thinner CRCP (i.e., 7-8 in.) has been poor, and is showing an accelerated rate of distress development over time. The amount of distress expected to occur, and the maintenance effort required in the next several years points strongly toward a need for the development of more efficient and durable ways of maintaining CRCP.

In previous studies, the performance of bare and resurfaced jointed reinforced concrete pavement (JRCP) and continuously reinforced concrete pavement (CRCP) on the Illinois freeway system was assessed by survival analyses. In this study, the 1994 data have been used to update the survival analysis of JRCP and CRCP and to carry out an initial survival analysis on the full depth asphalt sections (HMAC) of the Illinois freeway system. First and second asphalt concrete (AC) overlays were analyzed separately. Data for the survival analysis were retrieved from the Illinois Pavement Feedback System (IPFS) database. The Illinois freeway system consists of over 2,000 centerline miles (3,218 km) of heavily trafficked multiple-lane pavements which were constructed largely between 1957 and 1994. As of 1994, about 32% of these pavements had been overlaid once with AC ranging in thickness from 1.5 to 7.0 in. (3.8 to 17.8 cm). About 26% of these have been overlaid for the second time with AC ranging in thickness from 1.5 to 7 in. (3.8 to 17.8 cm).

Two previous studies on the survival of bare and asphalt-overlaid concrete pavements on the Illinois Interstate highway system were updated to reflect the performance of the pavements through 1991. The Illinois Interstate system consists of about 1750 miles of 10-inch jointed reinforced concrete pavement ORCP) and continuously reinforced concrete pavement (CRCP) ranging in thickness from 7 to 10 inches. As of 1991, about 60 percent of these pavements had been overlaid with asphalt concrete (AC), ranging in thickness from 1.5 to 6 inches. Data for the survival analysis were retrieved from the Illinois Pavement Feedback System database. Both in-service life and accumulated 18-kip ESALs at rehabilitation were estimated for bare pavements categorized by type, thickness, and D cracking susceptibility, and for overlaid pavements categorized by overlay thickness, overlaid pavement type, and D cracking susceptibility. The results show the effects of D cracking, traffic level, pavement type, pavement thickness, and overlay thickness on performance of bare and resurfaced concrete pavements.