Over 6 days, during what they called Concrete Week, The Guardian published on its website more than 10 different articles ranging from “Concrete: the most destructive material on earth” to “Delicate sense of terror: what does concrete do to our mental health?” Concrete is blamed for flooding, urbanization, respiratory diseases, depression, and government corruption. In contrast, in the next paragraph, they note that concrete is literally the foundation of modern civilization and that there is no substitute. So which is true?
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Even the most ardent proponent of concrete would admit that there is an environmental cost to manufacturing and building with concrete. Large holes are dug in the earth to extract the raw materials—limestone, sand, gravel. Carbon dioxide is emitted making cement. Many of our concrete structures don’t prove to be as durable as promised. But we do our best, at least in most of the developed countries of the world, to minimize those impacts. According to the Portland Cement Association, “Over the last 40 years, U.S. cement manufacturers have reduced the energy used to produce a metric ton of cement by roughly 40 percent.”
The Guardian does mention some of the health benefits realized through the use of concrete, such as a project in Mexico and a similar project in Bangladesh where, according to Archive, simply providing concrete floors in homes where children had been on dirt floors resulted in “a 78 percent reduction in parasitic infestation, 49 percent reduction in diarrhea, 81 percent reduction in anemia, and up to a 96 percent improvement in cognitive development.” But then The Guardian points out the damage to workers’ lungs from silica dust, which the construction industry in the Western world has begun to strongly address.
In response to these articles, Jeremy Gregory, Randolph Kirchain and Franz-Josef Ulm at the MIT Concrete Sustainability Hub, wrote that “concrete enables prosperity. Through its affordability and availability, concrete creates the infrastructure that has allowed millions to live safe, sanitary, and prosperous lives.” They also point out that it’s unethical for developed nations that have benefited from the use of concrete for many years to now try to limit concrete use in the developing world.
Let’s look at some of the more serious claims in The Guardian’s articles:
- Concrete pavements “entomb vast tracts of fertile soil, constipate rivers, choke habitats and – acting as a rock-hard second skin – desensitize us from what is happening outside our urban fortresses.” They say this means that floods, such as in New Orleans in 2005 and Houston in 2017, are made much worse because of paved surfaces. While it is true that impervious surfaces in cities increase runoff, blaming this on concrete seems unfair. In fact, most cities have more asphalt surfaces than concrete. We should also point to the availability and success of pervious concrete, although, granted, it is not used as much as it could be.
- Concrete “binds politicians, bureaucrats and construction companies” into a circle of graft and unnecessary government-subsidized construction projects made from concrete. This leads to construction companies—and by extension, concrete—that have distorted political systems around the world, especially in Japan, China, and Brazil. Again, to blame this on the use of concrete is unfair. If less concrete is used will corruption disappear?
- “If concrete was a country, it would be the third largest carbon emitter in the world.” While it’s true that carbon is emitted during the manufacturing of cement, it’s also true that there is no more durable material than concrete, which means that the impact is spread out over the life of the structure. And remember that the vast majority of cement manufactured over the past 20 years was in China, where environmental laws are much weaker. Emission reductions in North America would have minimal impact, not that the concrete and cement industries shouldn’t continue to implement new technologies to reduce pollutants; we should and we must.
In the end perhaps there is a benefit to having these issues raised. The concrete industry and the construction industry are working diligently on ways to reduce the carbon footprint of making cement and to find mixtures that reduce the cement content by using recycled materials (fly ash, even carbon dioxide directly), different binders, and more efficient internal structures (nanotechnology). These efforts need to continue and more quickly move into the mainstream. If The Guardian’s Concrete Week pushes the world towards that end then they have provided a valuable service.