How American architects reinvented “liquid stone”

Condensing one of the major periods of American architectural history into a single book is no easy task. So Roberto Gargiani, a professor at EPFL, wrote three. A New Era of American Architectural Concrete: From Wright to SOM, published by EPFL Press on 18 November, runs to more than 900 pages. “It’s huge, like America itself,” jokes Gargiani, who heads the Theory and History of Architecture Laboratory 3 (LTH3). His book explores how, between 1940 and 1970, reinforced concrete came to be a construction material of choice for American architects – in everything from houses to skyscrapers.

Enthusiasm for steel-framed buildings waned over the period as a result of the economic crisis. In the US, attention turned increasingly to concrete due to its versatility and widespread use in the post-war construction boom in Europe and Japan. The material had come very much back in fashion.

“Liquid stone”

Concrete is the main protagonist of Gargiani’s book, which is as expansive as the country that serves as its backdrop. Like an archaeologist unearthing artifacts one layer at a time, the author digs deep into the people and organizations – architects, engineers and design firms – that shaped this revolution. “The book centers on concrete: on how the material evolved and on the structures, finishes and details that it made possible,” he explains.

In the early 1940s, many of the biggest names in architecture – from pioneer Frank Lloyd Wright, to Louis Kahn, Paul Rudolf, I. M. Pei, and Skidmore, Owings & Merrill (SOM), one of the world’s most influential architecture firms – set about reinventing so-called “liquid stone.” Gargiani explains: “After World War II, architects started looking at the material with fresh eyes: at its properties and at its structural and expressive potential. Concrete, in all its facets, really came into its own.” Gone was the long-held belief that concrete should mimic real stone as closely as possible.

This shift in mindset gave rise to smooth, sleek, eye-catching buildings. US architects shunned the notion that concrete structures should look unpolished – a view espoused by Swiss-French architect Le Corbusier – and instead sought to achieve the perfection characteristic of freshly rolled steel. “Americans felt that concrete in its purest form was too austere. So they worked tirelessly on new products to give it a more sophisticated, textured appearance – one that would remain in place after the formwork was removed. Defects were anathema to American culture,” says Gargiani.

Prestressed concrete: The symbol of American capitalism

The period covered by Gargiani’s booked was marked by a flurry of patents and new inventions. The author focuses in particular on prestressed concrete, one of the major technical innovations of the time. Developed in Europe and subsequently adapted in the US, it involves placing predetermined stresses (in the form of metal rods or tendons) in reinforced concrete, in order to counteract the forces it will be subjected to in service. The rods or tendons react to tensile stresses, while the concrete itself reacts to compression – allowing engineers to design beams of unprecedented size and strength.

“Prestressed concrete symbolizes the might of American capitalism,” says Gargiani. “The corporate headquarters of many US firms were built using this technique. When you step inside, you can’t help but sense the power of the place. You realize that America is a civilization on an altogether different scale. Everything there is just bigger.”

After the 1970s, the advent of the postmodernist era signaled the end of American architects’ fascination with the “possibilities” of concrete. “As one chapter drew to a close, so another one opened. Concrete was once again viewed as artificial stone – something that should look like the material it’s supposed to mimic,” adds Gargiani.