ACPA Concrete Pavement Progress - Winter 2022-23

CONCRETE PAVEMENT PROGRESS 16 WWW.ACPA.ORG OVERLAYS (HIGHWAYS) US 69 North of SH 63 Extend North of Kiowa Pittsburgh, Oklahoma CONTRACTOR: Duit Construction Co., Inc.* OWNER: Oklahoma Department of Transportation ENGINEER: CEC, Inc. SILVER Iowa Highway 31 Woodbury/Ida/Cherokee County, Iowa CONTRACTOR: Cedar Valley Corp.* OWNER: Iowa Department of Transportation ENGINEER: Iowa Department of Transportation Situated in beautiful southeast Oklahoma, time was critical for the U.S. Highway 69 overlay due to the volume of truck traffic. The Oklahoma Department of Transportation decided to let the project as a full-thickness overlay that required milling the existing asphalt 9 inches to leave at least 4 inches of existing asphalt base. An 11-inch concrete overlay was placed over this base. This project was bid as a complete by date that allowed 180 calendar days administered as “overcome all.” Every delay had to be absorbed by the contractor to achieve a bonus or be charged disincentives. Prior to the construction of the concrete overlay on the northbound side, an asphalt subcontractor was required to resurface the southbound side with a 1.75-inch asphalt overlay. In true “Murphy’s Law” fashion, Duit personnel watched in horror as their asphalt plant caught fire and caused several delays that forced the project timeline to extend further than originally scheduled. These delays, along with cement shortages, supply chain disruptions and early COVID-19 restrictions, shifted paving operations into the wettest months in the region. However, Duit was able to complete paving within the scheduled timeframe. This project paid for the concrete by the cubic yard, so yields and overruns were to be managed as much as possible. The two biggest goals of this project included maintaining a good ride with all of the different control points and maintaining a low yield percentage overrun while controlling and maintaining proper thickness. Duit achieved a total bonus of $150,570 and maintained a low yield overrun on the concrete pavement. As to the thickness, no deductions were applied. Cedar Valley Corp.’s Woodbury/Ida/Cherokee County-Iowa Highway 31 contract was a hilly project that included 45 horizontal curves, 12 of which were superelevated. Highway 31 also boasted an astounding 108 vertical curves. The project had two bridge approaches poured half width by hand in order to maintain local traffic and then match with the mainline paving. The length of the project was 8.2 miles, and CVC crews placed over 137,000 square yards of paving. The project called for a nominal 6-inch thick, 24-foot-wide overlay with attached 2-foot-wide, 8-inch shoulders. A safety edge was also added on the outside shoulder. Combined, these pavements consumed 20,600 cubic yards of concrete. Occasionally the Iowa Department of Transportation invites contractors to run field tests to try out new concepts, or in this case, new materials. CVC agreed to incorporate synthetic macro-fibers at differing rates into test sections of various panel sizes. The hope was that the use of macro fibers would help prevent random cracking that often occurs during Iowa’s numerous freeze-thaw cycles. The fibers were incorporated into the mix at a rate of 4 lbs/CY, and the panels were sawed in varying sizes from 6 feet by 6 feet up to 12 feet by 15 feet. One additional test section was constructed with 1.875 lbs/CY to use fibers the contractor had on hand. The successful five-day trial in the fall of 2020 had CVC placing 20,602 pounds of fibers in 5,482 cubic yards of overlay concrete. All these areas of differing rates of fibers and panel sizes exhibit no random cracks through most of the two winters of freeze and thaw cycles. GOLD