CPAM Hosts Tour of Iowa Overlays

The Concrete Paving Association of Minnesota (CPAM) hosted a “Tour of Selected Iowa and Minnesota Highways” on November 6, 2014.   This tour was a repeat tour from 2007, with some new additions.  This year’s tour consisted of 14 personnel from Minnesota counties, one representative from the MnDOT State Aid Office, the Worth and Mitchell County (IA) Engineer, one staff member from the Iowa Concrete Paving Association and three staff members from CPAM.

The 2007 tour visited five concrete overlay projects ranging in construction dates from 1983 to 1993.  The concrete overlay design thicknesses ranged from 4½ to 6 inches thick placed upon asphalt pavement surfaces with little to no surface preparation.  Comments on the ride from the 2007 tour participants were that the overlays were “smooth” to “very smooth.”  Upon returning to these road sections in 2014, two of the road sections were still rated as smooth and the others were noted as “choppy” and “a little faulted” with some minor cracks.  Rich Brumm, Worth and Mitchell County Engineer, indicated his section (Mitchell County T38) is now ready for diamond grinding to smooth out the ride since the panels are not moving under the traffic loads.  The section of T38 we reviewed was situated next to a rock quarry and construction stockpile yard where frequent truck traffic is seen.

Three additions were made to the tour for 2014, which included overlays (one in Minnesota) with thicknesses ranging from 4 to 5 inches thick, and were constructed between 2009 and 2014.  The three new additions to the tour were also rated as “a smooth ride.”  The final stop in the tour was a 4-inch thick overlay, which was a 2010 American Concrete Pavement Association award winner.

The intent of this tour was to demonstrate the performance history of concrete overlays.  Although some of the older sections are now showing signs of some repair needs, these overlays continue to stand the test of time with little to no maintenance over their 20- to 30-year history.   Please contact CPAM with any questions.  View the complete report here.

StreetPave software use allowed by MnDOT

City, county and consultant engineers working on State Aid and Federal concrete pavement projects can choose to use the ACPA StreetPave software for jointed concrete pavement design. Download the Technical Memo. Learn how to get StreetPave12 on our Design Guide page.


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