CONCRETE PAVEMENT PROGRESS 12 WWW.ACPA.ORG Diamond Ground Concrete Proves to Be an Effective Way to Preserve Pavements IGGA Diamond Grinding White Paper Installment 2 of 3 In the Summer issue of Concrete Pavement Progress, we discussed the first installment of the International Grooving and Grinding Association (IGGA) white paper “Diamond Grinding: A Safe, Sustainable, Quiet and Cost-Effective Solution to Better Roadways.” In this issue, we continue with the second installment, on how diamond grinding can help preserve concrete pavement. Since its inception in the 1960s, diamond grinding has proven time and again to be the best solution to many common roadway issues. From its ability to provide a long-lasting surface for motorists while also reducing fuel and maintenance costs, to its natural tendency to capture carbon and reduce greenhouse gas emissions, diamond ground concrete pavements are a cost-effective option for roadway repair and replacement. Reduce IRI and Improve Roadway Smoothness As old concrete pavements begin to wear, they can lose their friction properties. Maintaining these properties is key to keeping highway systems safe for consumers. The State of Wisconsin determined1 that diamond ground surfaces resulted in a 42% reduction in all-weather vehicle accidents and a 57% reduction in wet weather accidents when compared to tined surfaces. In a publication in the Journal of Performance of Constructed Facilities,2 data was evaluated to determine estimated expected performance improvements due to diamond grinding in Texas. Data showed a single pass of diamond grinding reduces the value of the International Roughness Index (IRI) by approximately 40%. Many contractors affiliated with IGGA have reported even better results. When encountering extremely rough or faulted pavements, a high-quality finish can be achieved by implementing a light bump grind first to remove localized roughness before the full production grind. The same journal entry also reported a 30% improvement in skid number (SN), the metric used to identify friction issues in pavements. Case Study: Kentucky Improves Smoothness with Diamond Grinding Kentucky’s implementation of pavement management systems serves as a shining example of successfully staving off the need for extensive and expensive pavement reconstruction. By exploring the options available with Concrete Pavement Preservation (CPP), the Kentucky Transportation Cabinet made strides in determining data that can be used to trigger CPP. The most common CPP technique used in Kentucky is diamond grinding. The state has been performing diamond grinding since the mid1990s, but at that time they were just exploring options—little diamond grinding was being done. That changed in 2007, when the state increased its pavement preservation activities in an effort to improve the roadway system. Between 2007 and 2012, 536 interstate lane miles were diamond ground statewide, primarily in the Louisville area. During this period, IRI measurements for Kentucky’s interstate concrete pavements improved from an average of 112.1 inches per mile to an average of 74.5 inches per mile—the longest sustained improvement in the state’s IRI and their lowest recorded average IRI ever. The improvement was attributed to the 536 miles of diamond grinding that had taken place. The combined cost of the diamond grinding projects (including traffic control, patching, joint resealing and more) was $101 million, or $188,000 per lane mile. Reconstruction costs would have been an estimated $1.5 to $2.5 million per lane mile, so CPP saved the state more than $1 billion. The expected pavement life extension for ground pavement is 10 to 15 years. The average cost of diamond grinding in Kentucky during this five-year period was $2.75 per square yard. IGGA DIAMOND GRINDING
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