Punchout evaluations and classification of continuously reinforced concrete pavement to improve pavement design

In continuously reinforced concrete pavement (CRCP) research, it has been assumed that transverse crack spacing plays an important role in determining CRCP behaviour and performance. For the longitudinal reinforcement design, the 1993 American Association of State Highway and Transportation Officials (AASHTO) Design Guide recommends a minimum crack spacing of 3.5 ft. The minimum spacing of 3.5 ft is recommended to minimise the occurrence of punchouts. This concept of narrow crack spacing being more prone to punchout has been accepted. Hence, all the available CRCP design algorithms are based on this concept. However, since treated base/non-erodible base is now provided in CRCP, this theory has some discrepancies with the real CRCP performance especially in Texas. In this study, an extensive field evaluation was conducted for the number of punchouts recorded in TxDOT pavement management information system (PMIS). Out of 1472 punchouts, 232 punchouts that developed in major metropolitan Districts in TxDOT were surveyed and evaluated to determine whether punchouts have a relationship with closely spaced transverse cracks and the resulting load transfer efficiency (LTE). Field survey and testing results show that the majority of distresses in CRCP have been caused by quality issues of either materials or construction in the vicinity of transverse construction joint and repair joint.