I don’t know who invented concrete, though it has been in widespread use since the ancient Romans used it to build the Colosseum and miles of aqueducts, but I recently met the guy who is innovating it for building skyscrapers, conserving water, and fighting global warming.
Andreas Tselebidis is director of sustainable concrete technology and solutions at BASF, and his enthusiasm for concrete — which ranges from its molecules to its morality — started when he was a university student.
“Japanese researchers had pioneered concrete that was self-compacting and self-leveling, and my professor asked me to not only figure out why it worked, but how far it could go,” he said.
“I felt like it was a dare.”
A year and a half of almost incessant work followed that often left Tselebidis spending nights in the lab so he could get to work early the next day. He was fascinated by reactions between materials, and then their outcomes. “I wanted to know more,” he put it, with notable understatement.
Concrete is at once a simple and highly complex substance; it’s the result of the combination of a material, like sand or stone, and something that binds it together, most commonly cement. Things get complicated when you change either the materials and/or the glue, yielding different properties, mixing processes, malleability, structural integrity, durability, and even color.
BASF has been providing innovative solutions for concrete since the early 1900s. More than 100 years later, Tselebidis is looking at ways for concrete to be “as slender as possible, as stiff as possible, as quickly poured as possible, and as sustainable as possible.”
“What we’re building now came from the feedback and plans of our customers,” he explained. “We look to see how we can not only exceed their expectations, but use our science and practice as a platform for meeting newer demands.”
One example is BASF’s contribution to 432 Park Avenue in New York City, which, at 90 floors, is the tallest residential building in North America.
“The challenge was to innovate a concrete that could maximize floor space while providing structural support in a small footprint,” Tselebidis explained. “Plus, we needed to be able to pump it almost 1400 feet into the sky, expect it to be self-compacting and self-leveling, and it needed to be white.”
“We were the only ones who told the developer that it was possible.”
His team spent a month in the lab experimenting with various combinations, and another month preparing a demo for their opinion influencers: drivers, mixers, and other experts who would be responsible for using it. Changes were required in how temperature and time were managed, as making concrete is different at higher altitudes and lower temperatures than it is on warmer low ground.
The building gradually took shape, one floor every three days, and 432 Park now towers over midtown Manhattan.
The materials combination and processes that were used aren’t protectable, per se, but the expertise in developing and applying them are unique to BASF and, to a large degree, a result of Tselebidis’ passion for concrete.
BASF is currently at work on 64 large-scale projects around the world. Tselebidis is already experimenting with new potentials for concrete, like allowing its surface to change, control temperature, or conduct electricity (and thereby obviate the need for wall outlets).
He’s also working on optimizing the amount of cement used as the binder in concrete, since using it requires water, and making it produces a vast amount of CO2 emissions every year. Already, the concrete blend that BASF developed for use in New York’s Freedom Tower saved 1.1 million liters of fresh water, which he refers to as evidence of the “scientific morality” of concrete.
But I wanted to know what happened after he spent that year and a half sleeping in his lab at school. Did he succeed in proving the Japanese research?
“Oh yes,” he replied, with a broad smile. “Only now we’re taking concrete a lot farther.”