Wisconsin Experiences with Reflective Crack Relief Projects (05-1531)
Leonard Makowski, Wisconsin Department of Transportation
Phillip B. Blankenship, Asphalt Institute
Debra L. Bischoff, Wisconsin Department of Transportation
Daryl Sobczak, Milwaukee Department of Public Works
Fiona Haulter, No Organization

Many agencies place hot mix asphalt overlays on deteriorating jointed and/or cracked Portland Cement Concrete pavements to improve ride, protect the pavement structure and reduce noise. Reflection cracking of the joints and pre-existing cracks through the overlay is a persistent problem. In climates such as Wisconsin, the initial reflective cracks often appear within a year or two. Wisconsin Department of Transportation and the City of Milwaukee tried a fine aggregate, asphalt-rich, polymer modified asphalt mix interlayer to absorb joint movements, delay reflective cracking and protect the existing pavement. Four Wisconsin projects are discussed here. In the first project, constructed in 1996, the interlayer showed no effect on delaying reflection cracking within the first three years. Later projects, however, were specified using performance-related design tests for flexural beam fatigue and Hveem stability and were overlaid with improved mixtures to complement the flexible interlayer. These later projects showed an average 42 percent cracking improvement in delaying appearance of surface cracks as compared to the control sections. Further, cores taken from the projects showed that even when the overlay cracked, some of the interlayer samples did not, even under severe conditions; thus further protecting the underlying pavement structure. Other major factors contributing to the cracking delay included type of concrete pavement, concrete patches, and climate.