As our roadways continue to move towards more of a preservation mode versus new construction or full reconstruction, the concrete pavement industry continues to deliver new research and history on concrete overlays as a preservation method.  A long term preservation method.  Recently the National Concrete Pavement Technology Center at Iowa State University (CP Tech Center) along with the Iowa Department of Transportation and the Iowa Concrete Paving Association partnered to summarize 1,500 miles of roadway.  These concrete overlays have up to 40 years of pavement life to show how overlays on existing pavements can perform to provide a long term preservation to our existing pavements.  The entire document can be found here.  In summary, the document shows that 93% of overlays ranging from ages of 0-37 years were an average to good rating in the International Roughness Index (IRI) and 89% were in good to excellent condition in the Pavement Condition Index (PCI).  These facts and more valuable data can be found in a brief of the entire document on the most recent CP Road Map April 2018 publication.  The MAP brief can be found here.  I encourage you to read either document and consider a concrete overlay for the next pavement preservation project you have in your highway program.  A long term preservation can save your agency a significant amount of money in the long term life of the pavement.