BEHAVIOR OF EXPERIMENTAL CRC PAVEMENTS IN ILLINOIS

Determining the relationships between pavement behavior and the design variables (pavement thickness, type of steel reinforcement and depth of steel reinforcement) was one main objective of a study Illinois started in 1960. The pavement behavior, expressed in terms of deflection, transverse cracking, distress, and riding quality was analyzed and correlated with the design variables. The data were collected from six experimental projects constructed throughout the State during 1963-66. The investigation also includes instruments and procedures used to expand the knowledge on stress levels and ranges in the steel and concrete of CRC pavement. The findings indicate that the 7-in, and 8-in. (178-mm and 203-mm) CRC slab deflected greater than the edge of the standard 10-in. (254-mm) PCC pavement. The CRC slab thickness and the type of reinforcement have no effect on transverse cracking, but the depth of steel reinforcement has a major effect on transverse cracking. At the time of transverse crack development an abrupt change from compression to tension took place in the steel reinforcement. In general, the performance of Illinois CRC pavements since opened to traffic (11 to 14 years of service) has been quite satisfactory. A few localized failures have developed and were found to be caused by construction deficiencies, poor subbase drainage, and a higher level of load applications. /FHWA/