Recently, the city of Muskegon, Mich., decided to reclaim land that was once used to manufacture Sherman tanks during World War II. Its goal was to build a tourist area called Edison Landing, bordering on Muskegon Lake, which flows into Lake Michigan. This involved building Terrace Street, with a driving circle at the end as the entrance to the project. The original plan called for concrete unit pavers for the construction, but it was later changed to decorative stamped concrete. The architect, concerned about durability and aesthetic issues, took the unusual step of requiring the contractor to be certified by the manufacturer of the decorative materials used on the project. The Michigan Concrete Pavement Association (MCPA), Lansing, and Decorative Concrete Resources (DCR), who sold the decorative materials used on the project, provided technical help and specifications.
Western Michigan Recycled Aggregates (WMRA), Grandville, Mich., won the bid to install the roadway, but, because they didn't have experience stamping concrete, Nobel Concrete, Grandville, was invited to do the decorative portion of the work. Nobel is a certified installer for Increte products in Tampa, who supplied the decorative materials for the project. WMRA decided to use a slip-form paving machine to place 2-inch-slump concrete for the roadway. Thomas Richeal from DCR said there was great concern at the time, fearing the low slump would cause the concrete to be too hard before it could be stamped. But he said that after he had several discussions with Dan DeGraaf of MCPA, this approach began to make good sense.
The road into the project was the only way for construction traffic to access the site, so it was decided to place all the concrete on the straight portion of the street at one time to minimize the closure time. In order to reduce the problems that weather could cause, Nobel elected to work at night to gain steady ambient temperature conditions, reduce the possibility of surface crusting, and avoid faster setting times.
David Eerdmans, a partner and manager of the Decorative Concrete Division of Nobel Concrete, was also the lead person for his company on this project. He said the entire project was 25,000 square feet. Of this, 11,997 square feet were stamped and colored in one nighttime 9-hour shift. Nobel hand-placed and stamped concrete in the driving circle during daylight hours at normal levels of production.
Durability and maintenance concerns
Because the street would be in constant use, the city of Muskegon wanted high durability pavement that required little regular maintenance. In order to avoid repairs resulting from occasional scales that could expose plain concrete, both integral color and color hardener were specified.
Organizing for the straight portion of the street
The project participants weren't aware of anyone who had stamped concrete behind a paving machine before. So they were challenged to think through the issues on their own. WMRA built dispensing units for placing both color hardener and release powder.
Given the low slump, there was concern about wetting out and finishing the color hardener into the surface. So Increte's “Finish Delay” product was sprayed over the freshly screeded surface from the back of the slip-paver. “Autofloat” was added to the paving train to help with the finishing.
Nobel recognized that slump consistency between loads would facilitate predictable setting times between loads, so the slump was checked for each truck when it arrived onsite. If it was a load with too much water, it would set more slowly, causing them to fall behind with the stamping process.
The paving process worked as follows:
- Integrally colored concrete was placed and screeded by the slip-form paver.
- Next, a color spreader placed color hardeners at the rate of 60 pounds per 100 square feet.
- The Autofloat machine smoothed and floated the color hardener into the surface.
- Workers, using wood bull floats and hand floats, finished any area that the Autofloat missed.
- A spreader machine placed release powder on the finished concrete.
- The stamping team followed the paving train by approximately 50 feet, imprinting the pattern.
Eerdmans says that the operation went very well—better than they expected. The four-man stamping crew was able to keep up with the paving machines. And they were able to stamp right up to the unsupported edges of the pavement without causing them to slump over. With enough stamps for two rows at a time, there were no pattern alignment problems. Workers calculated that they placed their stamps more than 1800 times during the night.
Before the street was turned over to traffic, workers applied three coats of solvent acrylic sealer.