ACPA Quarter 2 2019

Concrete Pavement Progress www.acpa.org 14 K E N T U C K Y 9 C O N N E C T O R Aesthetically, the roundabouts, along with the relocation and design of the roadway, serve as an attractive, easy-to-travel entry into the city of Newport, says Seiter.The main roundabout has a 125-ft radius and is a 40-ft-wide roadway for two lanes of traffic, and the second roundabout has a 105-ft radius with a 40-ft-wide roadway and two lanes of traffic. “To my knowledge, these are the first concrete roundabouts in the state.” Being the first, meant researching joint patterns in concrete roundabouts in other states because the Kentucky specifications allow amaximumof 15 ft between joints, says John Eckler, P.E., prin- cipal engineer for the Lexington, Kentucky office of GreshamSmith. After consulting engineers in Michigan about their experience with concrete roundabouts, Eckler learned there aremany ways to space joints in a roundabout—depending on the number of lanes, radius of roundabout and number of approach roads. A spiral joint pattern was developed with special attention paid to eliminating any orphaned areas that might lead to cracking, says Eckler. “One question we had for others was whether or not to tie the transverse joint or leave it open,” he says. “We decided to do some of both by tying as much as we could, but in some areas, ties did not make sense.” These areas included joints on the outer arch of the roundabout, at the point where it exited to the mainline. “The angle of the mainline was not square with the joint, so it was left as an expansion joint,” he adds. The roundabouts were built one-half at a time so traffic could continue through the intersec- tion on the other half, says TimKnapke, project manager for Prus Construction. “The biggest challenge was phasing the paving work because we were also relocating utilities and upgrading the sewer system to separate stormwater from sanitary water.” Prus Construction Co. used a Kentucky Class P concrete mixture design that consisted of 35% gravel and 38% stone and a water/cement ratio of 0.49. Amid-range plasticizer and an accelera- tor also were used. The plasticizer allows crews to increase the slump of the concrete and work with the mix a little longer, which was needed because the concrete was placed by hand. “We machine screeded the concrete and added a red brick patterned concrete that served as the truck apron in the center of the roundabout,” says Knapke. The pavement is 10 in. thick and reached 3,500 psi in seven days. The concrete was provided by Hilltop Compa- nies, which is based in Cincinnati—just across the river from Newport. “Scheduling was the biggest challenge, because some of the mainline pours were large,” says Bud Ruffing, senior sales representative at Hilltop. The company used its batch plant that was located about 1.5 miles from the jobsite. The complex project was constructed over a four-year period in three different phases. In spite of the heavily populated, heavily traveled area, the project went smoothly, says Eckler. “We had a good team with a good plan and open communication with the DOT,” he says. “We were able to work together proactively to address any challenges.” » continued from page 12