Manatt's Inc., a paving contractor based out of Brooklyn, Iowa, just completed 12.5 miles (20.1 km) of a 13 mile (20.9 km) project. The onset of Iowa's harsh winter weather at the end of November had the company elect to finish the final 0.5 mile (0.8 km) of the project in the spring of this year.
They are building the new section of Highway 30 in Marshall and Story counties in Iowa with their GOMACO paving equipment, including a PS-2600 placer/spreader, two-track GP-3000 paver, four-track GHP-2800 paver, and a T/C-600 texture/cure machine. The new concrete highway is 26 feet (7.9 m) wide, 10 inches (254 mm) thick, and slipformed in one paving pass.
The Iowa Department of Transportation's (IDOT) specifications for pavement smoothness utilize the zero-blanking band with both incentive/disincentive pay built into the contract. Profile indexes on roadways with speeds greater than 45 miles per hour (72.4 km/hr) require a measurement of 26.1 to 40 inches per mile (411 to 630 mm/km) for full pay. Anything under 26 inches per mile (410 mm/km) earns incentive pay, with greater incentives offered as the numbers go lower. Anything over 40.1 inches per mile (631 mm/km) is penalized with a disincentive, and even higher numbers require corrective measures.
"When we go to work, we have 60 guys on the project who want to pave perfect every time, including the paving crew, plant personnel, and trucking," Kevin Hogan, Paving Superintendent for Manatt's, said. "Every single day we follow the same procedures in order to achieve smooth rides. We set up our paver the way we're taught in the GOMACO manuals, with a few of our own steps added. Everyone on site knows the steps and it's all about communication and organization."
It was Manatt's continuing goal of always achieving the perfect pavement that had them agreeing to work with GOMACO controls engineers and research and development personnel on their Highway 30 project. Manatt's had achieved 75 percent full incentive pay on the first seven miles (11.3 km) of the project.
They equipped their 2004 model-year GHP-2800 paver with GOMACO's new 5400 series mold and a rear-loading, front-inserting 5400 series bar inserter. Manatt's also upgraded the paver's G21 to a G22 controller to test new software upgrades. Improvements from the G21 to G22 include a new display with high-resolution deviations meters on the run screen. The meters display possible machine deviations in multi-colored (green, yellow and red) bar graph meters. They also assist the operator in fine tuning both grade and steering performance on the paver. The G22 also features new, proprietary smooth paving software which detects and eliminates any stringline hits and rod and knot bumps.
GOMACO engineers worked closely with Manatt's personnel during the testing. Two pan-mounted GSI® (GOMACO Smoothness Indicator) units on the GHP-2800 would constantly monitor the paving results. The process began the first day with Manatt's using their standard settings on the G22 and recording the results.
The second day, GOMACO's Controls Engineering Manager Mark Brenner adjusted the sensitivities. Then, on the third day, the new G22 software was installed and used for fine tuning the paver.
"With every step that we move forward with our controls development, our ultimate goal is to make machine operation less complicated for our users while improving paving accuracy," Brenner said.
The software, available for G22 and G+ control systems, has been designed in-house by GOMACO's controls experts who understand concrete paving. Before this new software, the operator working at the control console would need a person on the ground watching for leg movement while going through the threshold calibration procedure. The groundman would communicate movement to the operator and the operator would set and record the threshold and the process would be repeated for each leg of the paver.
"With this new software we have one-touch calibration for the elevation threshold," Brenner explained. "The operator holds a button down and has instant feedback from any movement of the leg displayed on the G22's screen. One person is making the adjustments from on top of the paver. We have eliminated an extra person from the set-up procedure. When that is done, the operator can then set the paver up to pave either stringline or stringless, and using the green, yellow or red deviation meters go through the process of high-definition tuning."
From the first day of operating with the new G22 software to the end of the project, Manatt's rideability readings continued to improve. Profilograph readings were taken using Manatt's high-speed profilograph.
After approximately five miles (8 km) of new concrete roadway was slipformed with the new G22 software and GSI monitoring capabilities, Manatt's averaged 17.95 inches per mile (283 mm/km) in the left wheel tracks and 17.72 inches per mile (280 mm/km) in the right wheel tracks. The haul road was located on the right side of the GHP-2800 paver. On IDOT's pavement pay chart, pavement segments averaging 22 inches per mile (345 mm/km) or less earn maximum incentive pay. In the state of Iowa, that equals an incentive of $950 per 0.1 mile (0.16 km) segment per lane.
"We always have different variables popping up while we pave, from temperature variations, concrete slump changes, to everything else," Hogan said. "The new G22 and the GSI work together to help us overcome those variables and solve any problems immediately. It's a huge asset for a contractor to have. Before, if we were getting questionable numbers, we didn't know until 24 hours later when the ride report was output from the profilograph readings. Now, the GSI is constantly tracing throughout the day and alerts us to any imperfections. It eliminates a lot of guesswork.
"It's a very simple process, too, from calibrating our machine each morning to setting up the GSI. That much technology and information can be overwhelming, but Mark Brenner was easy to work with and easy to learn from and now it's all just an easy fit for us. There's so much precision there now in the small adjustments. We didn't change our paving method, just the technology behind it."
Paving production on the Highway 30 project averaged approximately 3800 cubic yards (2905 m3) per day, with several days averaging over 4000 cubic yards
(3058 m3). Manatt's had their mobile batch plant on site mixing the IDOT approved concrete mix. Concrete was delivered to the job-site in trucks carrying eight cubic yard (6.1 m3) loads. The trucks dumped onto the belt of the GOMACO PS-2600 placer/spreader working ahead of the paver.
The paver's 5400 series bar inserter placed a 30 inch (762 mm) long, #4 bar every 36 inches (914 mm) into the 10 inch (254 mm) thick concrete slab. A burlap drag was applied behind the paver, followed by the GOMACO T/C-600 applying the texture and curing compound.
"Our last six miles (9.7 km) of paving on the project this season just kept getting better and better," Hogan said. "We earned 92 percent of our smoothness incentive pay and on the entire 12.5 miles (20.1 km) we earned 86 percent. We were producing a really nice slab."