Dowel Bar Retrofit Performance in Wisconsin: Fid-Bau Portal

Dowel Bar Retrofit Performance in Wisconsin

I. K. Battaglia

In 1999, WisDOT constructed test sections on I-39 to evaluate the dowel bar retrofit (DBR) rehabilitation technique for faulted concrete pavement slabs. Two years later, mortar deterioration and debonding were noted in the dowel slots. In response to this early distress, additional test sections were constructed on STH 13 to evaluate various mortar materials. The I-39 project was repaired, and test sections from both the I-39 and STH 13 projects were monitored between 2001 and 2007 for distress (PDI), pavement smoothness (IRI), and load transfer efficiency (LTE) between adjacent slabs. Additional DBR projects on USH 45, STH 21, and USH 18/151 were also surveyed in 2010. Six years after repairs were made on the I-39 project, distressed dowel slots were noted again, and additional repairs were made. The entire project was eventually overlaid with HMA. Prior to the overlay, however, IRI values were low for sections with DBR. Smoothness varied for control sections that were diamond ground only. The control sections with a 3-in HMA overlay and with diamond grinding only had the roughest ride in the driving lane. DBR sections had consistently better LTE values than non-doweled sections. Among the STH 13 test sections, mortar with 100 percent extension ratio had more debonding and surface deterioration than mortar with lower extension ratios (60 or 80 percent). Mortar and joint deterioration occurred on the USH 45, STH 21, and USH 18/151 projects, but areas of very good performance were noted as well. While DBR is a more expensive rehabilitation option than diamond grinding or HMA overlay, it addresses the root cause of slab faulting and provides the longest service life. If slab faulting is severe in the driving lane and not in the passing lane of a multi-lane highway, it may be possible to perform DBR in the driving lane only. Additionally, use of quality materials and attention to details during construction are critical for long-term performance of DBR projects.