Researchers look for clues in century-old concrete street

By Jane Nordberg

CALUMET - One of Calumet Village's unassuming residential side streets is receiving renewed attention from engineers and archeologists.

Faculty members and researchers from Michigan Tech University's civil and environmental engineering department and social sciences department drilled a 6-inch core sample last month in the 800 block of Portland Street in the Village of Calumet, a thoroughfare which for years has posted a sign as being "Michigan's Oldest Concrete Pavement."

The core sample will undergo a petrographic analysis to help the researchers learn more about the materials, proportions, workmanship, construction practice and quality of the concrete, said Karl Peterson, a research engineer with MTU's civil and environmental engineering department.

Believed to be constructed in 1906, the pavement is an early example of the once-popular "Rudolph S. Blome Granitoid Pavement" used in cities throughout the Midwest, of which only a few are still in service today, Peterson said. At least one, in Grand Forks, N.D., is on the National Register of Historic Places.

The analysis, which will be done in-house at MTU, would arm researchers with more knowledge of why the pavement has survived 100 years, if not the specific proof that it has.

"It doesn't pin it down to a specific year, but looking at the materials used, we'd be able to narrow it down to a five-year period or so," Peterson said.

Because the street is still in use, drilling was done off to the side of the road so as to not impede current traffic, as well as to provide the most intact sample. Unfortunately, the chosen spot was under a 4-foot snowbank, so industrial archeology graduate student Patrick Corcoran was set to work.

"I'm in archeology, so I don't mind shoveling," he explained.

Meanwhile, civil engineering professor Jim Vivian prepared and primed a Hilti DD130-RIG wet diamond drill, which was then placed over the recently cleared pavement.

Three somewhat noisy minutes later, Peterson pried the sample free with a screwdriver.

"If you look closely, you can see the flecks of copper in there," said Peterson, as he examined the 8-inch-long core sample with Corcoran and civil engineering research associate Matt King.

Peterson said the sample showed all local materials, with about 6 inches of what looked like red sandstone covered by a 2-inch fine concrete cap. After drilling, Peterson scraped another 4 cups of loose sandy material out of the hole, then he and King patched the hole with new concrete. As they were pouring, Corcoran threw a 2006 coin into the hole in case future researchers were interested when the hole was drilled. Corcoran's brainwave was just one of the reasons Peterson cited as a benefit of collaboration between the two departments.

"It's good to have some qualified archeological people around, because they seem to have a lot of good ideas," Peterson said. "As engineers, we're looking at some of the aspects while they might be interested in something very different."

Peterson also was grateful to the Calumet Village council, which approved the drilling only two days prior.

Members of the civil engineering faculty are interested in publishing the results of the core sample analysis in the proceedings from the International Conference on Long-Life Concrete Pavements this spring in Chicago.

This article is from the Daily Mining Gazette, and is reprinted with permission.