WWW.ACPA.ORG 17 Winter // 2022–23 OVERLAYS (STREETS & ROADS) Adams Center Roundabout Improvements Allen County, Indiana CONTRACTOR: Primco* / Milestone Contractors LP* OWNER: Allen County Highway Department ENGINEER: Engineering Resources SILVER County State Aid Highway (CSAH) 13 Concrete Overlay Nicollet County, Minnesota CONTRACTOR: Croell, Inc.* OWNER: Nicollet County Public Works, Minnesota ENGINEER: Nicollet County Public Works, Minnesota This project was a great success story where Allen County called the Indiana ACPA chapter for help solving a problem with rutting and peeling asphalt on an existing asphalt roundabout. The roundabout had been overlaid three times, trying to solve the pushing of the asphalt from heavy truck traffic speeding through on a daily basis. ACPA and Allen County representatives and developed specifications for a new 6-inch QC-QA concrete thin bonded overlay. This specific roundabout has three roads intersecting it with five different entry/exit points. The County allowed for a total closure of the roundabout to help expedite the construction process and minimize the impact on the traveling public. Once closed, a mill machine was used to mill transition and scarification in the asphalt shoulder areas, as well as mill 4.5 inches of asphalt off in areas to be overlaid. Primco then performed the 2- to 14-foot slip paving days around the radius of the roundabout. Multiple hand pours completed the roadway transitions between the roundabout and adjacent asphalt roadways. The last step was paving on the shoulders, a couple of transition areas, and final lane markings before opening to traffic. This was the first time liquid flyash and ES internal curing admixture were used together for slip-form pavement. The mix was great, and it slip formed and finished perfectly. The ES curing admixture and liquid fly ash were used in the concrete mixture with fiber for the portland cement concrete (PCC) thin bonded overlay. This mixture has become popular in other aspects of construction, but this was the first time Primco used it in a PCC concrete overlay process. County State Aid Highway (CSAH) 13 provides a connection between Minnesota Trunk Highway 14 and Trunk Highway 99 and is a 10-ton/axle-load carrying capacity road that is heavily used by traffic generated by businesses in the industrial park in North Mankato, Minnesota. It also provides a vital route for the agricultural industry in Nicollet County to service farmers in the County and allows those same farmers to deliver their goods to agricultural processing facilities in the Mankato/North Mankato region. The existing bituminous surfacing on this particular segment of CSAH 13 was showing significant pavement distress and decreased ride quality since it was last paved in 1996. Every spring, the 10-ton/axle-load carrying capacity was reduced to 7-ton/axleload carrying capacity to prevent further deterioration. This reduction of load-carrying capacity each spring for six to eight weeks severely hampered the heavy commercial traffic’s ability to haul full-capacity loads. It was determined that a concrete overlay was the best solution to restore CSAH 13 to a year-round 10-ton/axle-load carrying capacity, restore ride quality and provide an economical long-term investment. The project involved a profile mill removing approximately 2.5 inches of the existing bituminous and placing an unbonded 7-inch doweled concrete pavement over the 36-foot bituminous surface (including shoulders) for 5.3 miles. The contractor was required to develop a bituminous milling profile that restored proper cross slope on the tangent sections, superelevation and elevation transitions on the numerous curves. The paving profile ensured that a minimum of 7 inches of concrete pavement thickness was placed. The project had incentives/disincentives for pavement smoothness, coarse aggregate quality, water/cement ratio, and well-graded aggregate gradation. Croell, Inc. received a combined $233,810 in incentive pavements for their quality work. GOLD
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