Brief
The University of Wisconsin at Madison is completing a 113-year-old experiment testing the strength and durability of concrete cylinders exposed to various conditions. The aged concrete differs greatly from modern concrete due to chemical composition, but the experiments can provide some insight into the effects various environments have on the longevity of infrastructure.
Insight
FFor more than 100 years, engineers at UW-Madison have been conducting an experiment pitting ordinary concrete against the test of time.The project, initiated by faculty member Morton O. Withey, began in 1910 as a 10-year test of the strength of concrete in the form of 6-by-12-inch cylinders. Dozens more cylinders were added in 1923, with a third batch in 1937.
Since then, a half-dozen professors have served as caretakers of dozens of concrete samples throughout their tenures. The samples were stored in different environments — some were submerged in water, while others sat in the basement of the College of Engineering building protected mostly from humidity but not from carbon dioxide exposure from the air.
The samples have been tested at intervals over the years, but final tests have happened only twice: In 1987, researchers tested the 1937 batch after it had cured for 50 years. In 2010, the initial batch was tested at the century mark.UW-Madison professor Steven Cramer was there for both final tests, which involved subjecting the samples to dozens of tons of pressure. Even though he retired a year ago, he’ll be leading the tests of the 1923 batch later this year.
The results of the tests aren’t applicable to today’s concrete, because the chemical makeup of concrete has changed, Cramer said. Today’s concrete has air added to provide durability and it is ground into finer particles to increase how quickly it hydrates and hardens.
But while these tests can’t inform how, for example, the recently poured concrete on the Beltline or the interstates will hold up after years of driving and freeze-thaw cycles, Cramer said the centurylong experiment provides a snapshot in time as they look to extend the life of concrete.
“We build a bridge and we say, ‘Oh, this bridge will last 50 years,’ or we build, even more interestingly, a nuclear power plant, and we want that power plant to last a long time,” Cramer said.
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