Pavement Preservation Journal - Summer 2013 - (Page 9)

‘Thinning Up’ Concrete Overlays for Pavement Preservation By Bill Davenport AMERICAN CONCRETE PAVEMENT ASSOCIATION Photo shows D Construction, Inc. placing 4-in. concrete with 4 ft x 4 ft joint spacings for a total length of about 4 miles. The overlay was placed over old U.S. 66 alignment, and was designed using latest Illinois DOT design information for whitetopping and ultra-thin whitetopping. C oncrete overlays for asphalt and concrete pavements are thin, and getting thinner. Today, about 60 percent of concrete overlays are placed on asphalt pavements, compared to the early days when they were almost all on concrete. “Concrete overlays have been around since the early 1900s,” said Gerald F. Voigt, P.E., president and CEO of the American Concrete Pavement Association. “There were an estimated 350 concrete overlays placed between 1910 and 1990, but it wasn’t until the 1990s that overlays became more prevalent.” That is, in the late 1990s, the focus among ACPA’s agency partners went beyond overlays on concrete to include overlays on asphalt pavements. “Some of the early groundwork in concrete overlays of asphalt pavements dated to the early 1980s, with projects done on county roads in Iowa, as well as parking lots in various parts of the country,” Voight said. “We learned a lot from Iowa, including some useful information about thinner concrete overlays.” “Iowa and certain other states started constructing concrete overlays about 30 years ago to meet the mid- range needs of agencies,” said Dale Harrington, P.E., senior project engineer at Snyder & Associates, representing the National Concrete Pavement Technology Center at Iowa State University [CP Tech Center]. “They turned out to be a long-term serviceability solution for county roads and state highways in Iowa, and for many years, this was our standard approach to overlays.” Things began to change after a question was posed by ACPA staff asking “Why can’t the concrete pavement industry do a 2-in. mill-and-fill?” A short time later the first reported “ultrathin” concrete overlay was placed on asphalt at a landfill in Louisville in 1991. “This innovation is illustrative of the benefits that occur when industries compete,” Voight said. CHANGING DYNAMICS With more than 80 years of use, concrete overlays have evolved into a time-tested technology, and increased acceptance has led to increased use. “Today we are seeing concrete overlays account for about 10 to 15 percent of the square yards of concrete placed on an annual basis,” Voigt said. Summer 2013 pavement preservation journal 9

Table of Contents for the Digital Edition of Pavement Preservation Journal - Summer 2013

President’s Message
‘Thinning Up’ Concrete Overlays for Pavement Preservation
IGGA: After Five Years, Colorado CPR Project Holds Strong
Joint Meeting Brings ARRA, ISSA, AEMA to California Desert
At NCAT Preservation Study, Performance Clues Emerge
Integrated System Keeps Fort Collins ‘Asset Smart’
New Alaska Database Aids Treatment Selection
GPR, FWD Analyze Airfi eld Pavements in South Carolina
TPPC: In Texas, Fog Seals Should Last 18 Months
Caution Due in Using MC-30 as Prime Coat
In Nevada, Cold Recycling Preserves I-80
Index of Advertisers

Pavement Preservation Journal - Summer 2013