Manny Amorim, owner, and Spiro Mitrou, resident engineer of A-Tech Concrete in Edison, NJ, wanted to reduce the cost of a 109-kilometer (68 mi.) rehab project that A-Tech won in the state of New York.
According to Amorim, the parkway is the biggest curb job in the history of New York State.
The specs called for a white grout cap, poured on a base concrete curb. The base curb is to be buried under asphalt. The white cap will be the only part of the job exposed to the human eye, Mitrou said. The white grout contains white cement and white sand proportioned at 2-1 ratio.
The white grout will provide reflectivity for maximum brightness to help make the Palisades Parkway safer for travelers.
Also thrown into the specs was an imprinted facet to be placed on top of the white grout, which will reduce rainwater velocity when it barrels into the curb. The rainwater could create a driving hazard if it isn’t slowed, Mitrou said.
A-Tech wanted to perform all the steps in a single pass, including the imprint.
A-Tech was awarded the contract in June of 1999 from Halmar Builders of Mt. Vernon, NY. Halmar is the general contractor of the $62-million project. The original start date for the curb installation was to be September of 1999. However, it was delayed until spring of 2000. The delay actually helped, according to Mitrou. “It gave us time to think how we could do it faster with the least amount of manpower,” Mitrou said.
“Everything we thought of doing by machine, we’re doing,” Amorim said. “The state DOT loves it. It’s the only way to do it. We have substantially reduced our anticipated manpower.”
A-Tech presented the objective to a team at Power Curbers Inc.
Engineer Mark VanHoy worked with fabricator karl Benz, welder David Osborne and engineer Alan Champion to design the mold to handle two different mixes simultaneously. The mixes had to bond together chemically so that the machine poured the cap while the curb was still wet. Two hoppers were required, and the second hopper required a vibrator.
“The key is the mold shell,” VanHoy said. “This is actually two molds in one, but the shell is never separated on the side. The sides had to be continuous. Each mold would have to have been perfectly aligned if we didn’t have continuous sides. It would have been impossible to weld.”
Weep holes were inserted to allow air to escape from the mix.
A knife was added to cut off the second mold and hopper, if needed for traveling through catch basins.
The curb is 34-centimeters (13.4 in.) wide and 38-centimeters (15 in.) tall with the cap. The cap is 3.8-centimeters (1.5 in.) thick.
In order to do the work in a single pass, the first hopper feeds concrete into the curb mold and the second hopper feeds white grout into the cap mold. A-Tech is using two mobile mixers to dump into the second hopper, which contains a vibrator.
Engineer O. L. Beaver designed the imprint, using a 23-centimeter (9 in.) drum that contains three patterns. Each pattern is 18.4-centimeters (7.3 in.) wide and contains seven distinct facets so there are 21 facets repeating over and over as the mold moves. One revolution of the drum imprints the pattern three times. The wheel is attached to the rear of the mold screed with plates so that when the wheel makes contact with the white concrete, the white concrete does not bulge but retains its shape.
A-Tech is using a misting attachment, an option for the 5700-B, to spray the imprinting wheel with a release agent so that it does not stick or shear the white grout cap.
The objective is to pour 610 meters (2,000 ft.) of concrete a day. “One full cement grout truck loaded provides 1,100 feet of cap to dump into the second hopper,” Mitrou said. “The second mobile mixer is loaded and ready to go while the first one is dispensing mix into the hopper. This avoids delays waiting on a mixer to be loaded.”
The parkway was built in the early 1950s in a number of phases, according to Tom McGuinness, project engineer for the New York State DOT. It is administered by the Palisades Park Commission, and an effort is under way to have it declared a historical highway. “The commission is very strong on keeping the aesthetics of the parkway,” he added.
That includes the appearance of the curb. The curb is “indigenous to certain highways in New York State dating back to the ’50s,” Mitrou said.
Previously, re-hab curb work has been done manually. “They would set up with conventional forms for the curb, mix mortar by hand and do the grooving by hand,” Mitrou said. “The most any contractor could do was 700 to 800 feet a day.”
Once A-Tech had its slipform process approved by the New York State Department of Transportation, the curb crew did two test runs with DOT officials. “They were extremely pleased with the results,” Mitrou said. “Everybody at Power Curbers gets a gold star.
“A-Tech was confident from day one that it would work, knowing that the substantial time and money invested in research and development of this process would be profitable.
Today's top stories
