Illinois Day: IDOT Uses Thin Concrete Overlay to Improve Performance
The ‘Every Day Counts’ initiative is a state-based model used to identify and rapidly implement proven yet underutilized innovations. Federal Highway Administration (FHWA) works with state transportation departments, private industries, local governments and other stakeholders to implement EDC innovations.
Illinois Department of Transportation (IDOT) has implemented multiple EDC innovations over the past decade including Measurement While Drilling (MWD) and Targeted Overlay Pavement Solutions (TOPS). These technologies shorten the project delivery process, reduce congestion, enhance roadway safety and improve environmental sustainability.
IDOT’s Innovative Approach to Site Exploration
This past summer, IDOT, with the help of researchers and members from the University of Illinois Urbana-Champaign and the University of Florida, implemented Measurement While Drilling (MWD) on a drill rig. A featured geotechnical method in exploration (A-GaME), MWD is a site exploration technique that allows for continuous monitoring of geotechnical drilling operations. Although MWD does not replace the process of sampling, it does supplement other subsurface exploration projects and reduces the number of physical samples required.
By combining research and program delivery projects, IDOT implemented MWD.Through adopting MWD, they developed relationships between MWD parameters and geomaterial condition and strength. Using this method, instrumentation is added to standard drill rigs which provides crew members and engineers with real-time, continuous measurements of a project’s drilling parameters.
The data collected by this technique produces profiles of drilling parameters to reveal soil layers and additional subsurface properties. This information leads to more accurate strength assessments of soil and rock. Interest in MWD continues to grow as several state DOTs are purchasing, training and using the site exploration method.
Sources for social copy: https://www.fhwa.dot.gov/innovation/everydaycounts/edcnews/20220929.cfm
Over a Decade of Excellent Performance: Richard County’s Use of Thin Concrete Overlay
In 2010, Richard County placed a concrete overlay on top of the asphalt surface of County Highway 9 in Richmond County, IL. After more than a decade since its installation, the overlay continues to perform tremendously and has proven itself to be an invaluable, innovative solution.
“This project provided Richland County with competitive bids, rapid construction, minimum inconvenience to residents, and a smooth-riding, long-lasting pavement,” said Richland County Engineer Danny Colwell.
The overlay was placed over the 22-foot-wide asphalt road that serves as a popular trucking route for those who are headed to grain elevators and oil fields. Crews milled the existing asphalt pavement down to a 1-inch depth and then constructed a 5.5-inch concrete overlay with macrofibers. Prior to the overlay’s installment, the pavement distress included shrinkage of the soil-cement base which resulted in transverse cracks along the asphalt road.
This approach is a targeted overlay pavement solution (TOPS), a solution for combining innovative overlay procedures into operations that ultimately improve performance, reduce the cost of pavement ownership and lessen traffic impacts. With most pavements in the National Highway System (NHS) having reached, or approaching, the end of their design life, TOPS provide long-life performance under a wide variety of environmental, traffic, and existing pavement conditions. These concrete overlays benefit from recent improvements to design practices, slab geometry and interlayer technology. As a result, consumers are able to improve overlay surface treatment applicability, sustainability and cost-effectiveness.
Sources for social copy: https://ws.engr.illinois.edu/sitemanager/getfile.asp?id=3688
SOURCES: FHWA, IDOT