Brief
Discover how the Oklahoma Department of Transportation is transforming road repair with CAM, a self-healing asphalt mixture that prevents cracking, and its impact on the state’s road infrastructure.
Insight
The Oklahoma Department of Transportation (ODOT) has reported success in using a self-healing asphalt mixture that prevents cracking, known as Crack Attenuating Mixture (CAM).
In 2012, ODOT utilised CAM for a repaving project on the I-40 in Caddo County. A decade later, the 2-mile section boasts an International Roughness Index (IRI) averaging 50 inches per mile. According to the Federal Highway Administration (FHWA), this is smooth enough to qualify for ride quality bonuses for new construction in some states. A desirable IRI is considered to be less than 95 inches per mile.
For the I-40 project, CAM was combined with ODOT’s highly modified asphalt binder as an intermediate layer. The project has since been nominated for a Perpetual Pavement by Conversion Award from the Asphalt Pavement Alliance. Following the I-40 project, ODOT has applied CAM to various roadways, from interstates to county roads throughout Oklahoma. The FHWA states that “CAM has proven to be a practical, effective, and economical approach to delaying or preventing reflection cracking.”
ODOT recently awarded a contract for milling and repaving a 7-mile stretch of I-40 in Canadian County, where CAM will be used. The project entails milling 7 inches of existing asphalt, placing a CAM layer, and then adding Superpave and stone matrix asphalt on top. The $24 million project is expected to commence in the summer and deliver high-quality pavement for 15 years.
ODOT District Engineer Trenton expressed enthusiasm for the project, stating, “We’re extremely excited about it, because currently, we must conduct daily repairs. We have to close down a lane, mill out a section, add new asphalt, and then repeat the process 5 feet ahead. This project will provide us with durable pavement that doesn’t require constant maintenance.”
Originally designed by the Texas Department of Transportation in 2007, CAM has been used extensively in Houston and Dallas atop old concrete pavements. While it has primarily been utilised as an interlayer between existing pavement and a thin asphalt layer, it has also been placed as a 0.5- to 1-inch surface course. The FHWA confirms that CAM is both rut and skid resistant.
Highlight
- The Oklahoma Department of Transportation (ODOT) has reported success in using a self-healing asphalt mixture that prevents cracking, known as Crack Attenuating Mixture (CAM).
- In 2012, ODOT utilised CAM for a repaving project on the I-40 in Caddo County. A decade later, the 2-mile section boasts an International Roughness Index (IRI) averaging 50 inches per mile.
- . The FHWA states that “CAM has proven to be a practical, effective, and economical approach to delaying or preventing reflection cracking.
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