Cold In-Place Recycling Forensic Study on U.S. Highway 34 Union County, Iowa

Forensic studies of pavement failures require a clear understanding of the distress observed, a logical approach to examining potential assignable causes, a reasonable connection between the distress and assignable causes, and recommendations to minimize the potential for future failures. The recommendations must be careful to address the cause and to not unduly restrict technology that has a proven record of success. This case study on cold in-place recycling demonstrates this process. Cold in-place recycling is a successful rehabilitation strategy. As we learn more about this technology, we also learn about its limitations. The dramatic failure of the cold in-place recycled layer under traffic on the U.S. Highway 34 project was investigated. Eleven separate factors were analyzed as possible assignable causes. It was concluded that the level of truck traffic was the primary cause of the failure. The application of cold in-place recycling technology is currently restricted to less than 400 trucks per day until changes are made to the mix design to address higher truck traffic levels.