The origins of concrete as a construction material are debatable. It is found as far back as the ancient Egyptians who used gypsum and lime to make mortars. There is also evidence of desert traders over 8,000 years ago using concrete to make underground water cisterns. However, it is clear that concrete was first widely used in the way we know it today by the Romans, who used concrete to form arches, bridges, aqueducts, vaults and domes such as the Pantheon (approx. 113 AD). The Pantheon to date remains the world’s largest unreinforced concrete dome and a timeless work of architecture in its own right. Other famed Roman concrete works include the Colosseum (80AD) and Arch of Septimius Severus (203 AD), all still standing today as a testament to the durability of Roman concrete.
The precise recipe the Romans used to mix their concrete however has been ‘lost.’ Vitruvius wrote in his Ten Books on Architecture (25 BC) about specific types of aggregate appropriate for structural mortars and recommended pozzolana, a volcanic sand. His specification was 1 part lime to 3 parts pozzolana for concrete used in building works and a 1:2 ratio of lime to pozzolana for underwater concrete work, which is interestingly a similar ratio to that used today.
Following the fall of the Roman empire, concrete as a construction material largely fell by the wayside. It was not widely used again for approximately 1,4000 years when it was re-pioneered by France in the mid-19th century and innovated further in the United States by engineer Ernest Ransome, who introduced the concept of reinforced concrete after finding that pouring concrete over iron or steel bars dramatically increases the strength of the resulting material. He would go on to construct the Artic Oil Company Works warehouse in San Francisco. Completed in 1884, the reinforced concrete warehouse survives to this day.
In the 1920’s, concrete was still very much in its infancy when Frank Lloyd Wright began to experiment with it. In 1924, for the design of the Ennis house, he decided to work with concrete block. ‘The concrete block? The cheapest (and ugliest) thing in the world. Why not see what could be done with the gutter-rat?’ he wrote. In total, the Ennis house is made of 27,000 concrete blocks arranged across a concrete platform and buttressed by a retaining wall. The concrete blocks are a combination of gravel and sand from the site. The blocks were hand-cast in aluminium molds and woven together with steel rods.
The house was a noted favourite of Lloyd Wright’s, he was pleased with the unique texture and the cost/ease of construction. He would go on to use concrete in many of his most famous designs, such as Fallingwater in Pennsylvania and of course, the Guggenheim Museum in New York (1959), with a spiral ramp that broke all the rules of concrete to date.
Appearing impossibly lightweight, the Guggenheim’s famed ramp was made of expanded shale concrete. Meanwhile, normal weight concrete was used for bearing walls. The sensuous forms of the exterior did not immediately receive critical praise, being described by critics, among other things, as an ‘inverted oatmeal bowl. Today, it remains one of the world’s most visited architectural icons.
In the 1930’s, the expressiveness and playfulness of concrete continued to evolved. One key project of the era was the Berthold Lubetkin and Tecton Group penguin pool (1934) at the London Zoo. Designed in collaboration with Ove Arup, it is notable for its impressively thin, interlocking spiral ramps, which extend from hidden columns. In contrast to the traditional method of casting concrete as a column or beam, Arup advanced the idea that concrete slab or panel was the most effective form for reinforced concrete and that any shape could be formed with it.
By the 1960’s, concrete was commonplace as a construction material and finding favour from the world’s greatest architects of the era. Particularly iconic in this regard is the work of Oscar Niemeyer and the National Congress of Brazil, Brasilia (1960).
Rejecting right angles, he instead favoured liberated, sensual curves found in ‘the mountain of my country, in the sinuousness of its rivers, in the waves of the ocean and on the body of the beloved woman.’ His love of concrete continued throughout his lengthy career. More than 30 years later he would complete the Niteroi Contemporary Art Museum in Rio de Janeiro, another masterwork in concrete.
In recent years, architects have continued to push boundaries with the use of concrete. Toyo Ito’s Meiso no Mori Municipal Funeral Hall for example features a wafer-thin shell of concrete that makes the roof form appear to float – despite its weight. It comes from his experimentation with formwork and insertion of steel meshes where necessary to give strength while maintaining an incredible thinness.
In addition to boundary pushing form, architects have also demonstrated the textural possibility of concrete. One example of this can be found in the stunning curves of Norihiko Dan’s Sun Moon Lake Visitor Centre in Taiwan (2010). Here, in situ concrete carries the grain imprint of the wood that is used for its mold.
Another example of textural depth and intrigue can be found in the Nottingham Contemporary by Caruso St John Architects. Made of a continuously patterned surface of pale green pre-cast concrete elements, the concrete used is cast with the pattern of Nottingham lace. To create the effect, this renowned type lace was scanned and then scaled and tiled to develop an overall image. This image was converted into a three dimensional model that was used to drive a milling machine that produced full size MDF sheets engraved with the lace. These sheets were then used to create latex molds, which in turn were then used to cast the building’s pre-cast ‘lace’ concrete elements.
All said, concrete certainly has its drawbacks. It is for example often associated with drab office and housing blocks and uninspiring carparks. Even more topical is its carbon footprint. As the second most used material on earth, concrete is also the second largest emitter of C02, accounting for an estimated 5 to 7 percent of global emissions. Uncomfortable with the environmental consequences of using concrete, many designers, architects and innovators are developing and looking at alternatives.
Much of the research for concrete alternatives focuses on the mixture of concrete itself. MIT researchers for example are looking at ways of manufacturing concrete using an electrochemical method that can capture CO2 before its release. The captured CO2 can then be used in the drinks and fuel industry.
Other innovations include 3D printing technologies with concrete, which allow the material to be more strategically and sparingly used. The world’s first 3D-printed community was completed late 2019 in Tabasco, Mexico, by 3D concrete printing pioneer ICON in collaboration with nonprofit New Story. The 500 square feet homes were each printed in about 24 hours.
Another recent innovation that goes hand in hand with parametric design comes in the development of GFRC (Glass Fiber Reinforced Concrete), which is a mortar made of concrete, sand alkali-resistant glass fiber and water. Lighter and thinner than standard concrete, it is also incredibly plastic. An example can be found in Changsha Meixihu International Culture & Arts Centre by Zaha Hadid Architects. The material is also being used in the ongoing works of Gaudi’s Church of the Sagrada Familia.
Given its history, prevalence and design flexibility, there is little doubt concrete will remain a favoured material of choice in the future of the building industry. One thing is certain though, that the evolution will continue.
This article was made in collaboration with Phaidon. To continue a beautiful and informative visual exploration, the book Concrete is available here.
