Repair of Ultrathin Whitetopping Pavements

Abstract

Since its inception in 1991, ultrathin whitetopping (UTW) has moved beyond the experimental stage and has become a viable pavement rehabilitation alternative. Development of the mechanistic design procedure in 1997 represented a milestone in the development of this technology. Over 150 UTW pavements have been built in the past decade. With the use of UTW rapidly increasing, the next logical step in the development of this technology is to develop UTW repair and rehabilitation techniques. How does one repair UTW pavements? Can conventional concrete pavement rehabilitation materials and methods be used for UTW pavements? Construction of the UTW test sections at the FHWA Turner-Fairbank Highway Research Center, subjected to accelerated loading tests, provided an excellent opportunity for evaluating potential UTW pavement repair methods. These test sections were constructed in April 1998 and were subjected to accelerated load testing with FHWA’s accelerated loading facility (ALF) from May 1998 until November 1999. Some UTW panels exhibited distresses, with corner cracking being the most prominent. After discussions with state agency staff and industry representatives, panel removal and replacement was selected to repair some of the distressed panels of these test sections. The repair work was done in April 2000 and the repaired test sections were load tested with ALF from May to August 2000. Based on the results of ALF testing, it was observed that panel removal and replacement is an effective method for UTW pavement repair. Guidelines for UTW pavement repair by this method are proposed. A strong bond between the concrete and asphalt layers, even for distressed (cracked) panels, was observed. The time required for UTW panel repair was also documented and can be used for planning UTW repairs.