Sawing and Sealing Joints in Bituminous Pavements to Control Cracking

Project summary:

Saw and seal, or the practice of sawing joints in an asphalt pavement and sealing them with a sealant, has been used in Minnesota since late 1960s. It started as a method to control reflective cracking in hot mix asphalt (HMA) overlays over concrete pavements (BOC), and over the years its use has expanded to other types of pavements, including bituminous overlays on bituminous (BOB) pavement and new bituminous pavements.

Surprisingly, the last comprehensive research effort investigating this method was published in 1996 by Janisch and Turgeon. Since many counties and cities use this method, there is an urgent need to reevaluate the benefits of this method and to provide improved guidance based on the materials used today, such as modified performance-graded (PG) binders, and a better understanding of the pavement system.

In this project, researchers want to address this need by first providing updated information on current use of saw and seal locally and nationally. Then, researchers will obtain and analyze relevant pavement management data for saw-and-seal sections in Minnesota, to identify possible factors responsible for the significant variation in performance, and to compare saw-and-seal with the use of modified PG asphalt binders, known to have better cracking resistance. Using pavement mechanics, researchers will investigate the behavior of pavements under various temperature scenarios and interface conditions to determine key material properties and construction parameters that affect the durability and performance of saw and seal sections, and to perform a cost/benefit analysis. Based on the results, researchers will develop best practice guidelines for application of saw-and-seal method, including recommendations on when to use it.