Continuously Reinforced Concrete Pavement: Identification of Distress Mechanisms and Improvement of Mechanistic–Empirical Design Procedures

In 2005, the Texas Department of Transportation initiated a rigid pavement database to collect information in preparation for the calibration and potential implementation of the Mechanistic–Empirical Pavement Design Guide (MEPDG) for continuously reinforced concrete pavement (CRCP). Twenty-seven sections, each 300 m (1,000 ft) long, were selected throughout the state. Deflection testing was conducted with a falling weight deflectometer. The information collected included load transfer efficiency (LTE) at small, medium, and large crack spacing for two different seasons, summer and winter. Also collected were crack-spacing information and slab deflections. LTE values for all the cracks were higher than 90% regardless of slab thickness, pavement age, crack spacing, or season. Mechanisms of primary distresses in CRCP were investigated. The investigation tentatively revealed that many distresses identified and recorded as punch-outs in Texas were not actually caused by structural deficiency. Rather, most of the distresses were caused by imperfections in design details, construction or material quality issues, or both. Horizontal cracking appears to be the major cause of distresses in CRCP in Texas. The interactions between longitudinal steel and concrete in response to dynamic wheel loading applications appear to be the cause of horizontal cracking. From the findings, mechanistic–empirical (ME) CRCP design procedures and a calibration function were developed. Because the accuracy of any ME design procedure depends to a great extent on the reasonableness of the transfer function, further efforts will be made to improve that function.