We use so much cement that it has become a serious problem. Solution: replace it with garbage

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From Tokyo to Madrid, passing through New York, Guadalajara, Vigo or Abu Dhabi. It doesn’t matter which city you look at; one thing is clear: wherever you look, you will most likely come across vast expanses of concrete. It has spread at such a speed, so consubstantial has it become with urban development, that it is estimated that its use has tripled over the last four decades and today it is already, in general terms, one of the most used materials in the world.

Based on cement we have built large metropolises, built houses, schools, squares, hospitals and shaped the world to our needs; but with each loaded concrete mixer we also pay a small (large) toll: a volume of pollution that the sector is already trying to minimize with “green” compounds, more respectful of the environment.

The cement rush. We use cement frequently. A lot. The data who was driving in February Oficemen, the Spanish association of the sector, show that in 2021 we reached 14.93 million tons, 11% more than the previous year. And it is not a phenomenon exclusive to Spain. It is estimated that we make more than 4,000 million tons annual. Moreover, three years ago Guardian estimated that so much is produced throughout the world that in a single day we generate enough to fill the Three Gorges Dam in China, the largest in the world.

“Not only are we using more cement than ever; we are using more cement per capita than ever,” explains to C&In Kimberly E. Kurtis, a civil engineer and expert at the Georgia Institute of Technology, who remembers how its consumption has skyrocketed in a matter of decades.

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The other bill for the environment. The deployment of cement has allowed us to expand our cities, build buildings, schools, hospitals, bridges, docks, airports, shopping centers… Perhaps the best example of that boom is Japan, which has starred in a real revolution that explains why, despite its small size, it houses more or less the same volume of material as the US and a much higher concentration of cement per square meter.

The less friendly “B side” of this reality is its serious impact on the environment. A recent study published in Nature shows that cement accounts for 36% of the 7.7 Gt of CO2 that the construction sector is estimated to release into the atmosphere. The data far exceeds that recorded by other materials used by the industry, such as steel, plastics, aluminum or bricks. In general terms, it is estimated that the cement originates between 4 and 8% of global CO2.

Other of its most palpable effects on the environment is its high water consumption —particularly serious in those regions most affected by severe droughts and the scarcity of water resources—, the generation of particles with a detrimental effect on health and energy demand.

A worrying trend. Perhaps the most worrying thing is that some reports suggest that, far from softening, this impact is getting worse over time. Greenpeace calculates that between 2017 and 2018 the cement sector increased its emissions by 2.6%, a trend that coincides with that drawn in the report Big Polluters UK 2019, prepared by the Sustainability Observatory (OS). Its authors calculate that —although Spain had reduced its total emissions by 4%— the cement sector had noted an opposite trend, with a rise of nearly 3%.

The Mission Possible Partnership estimates that over the next several decades, with a horizon of 2050, world cement production could increase up to 23%a considerable increase that collides with another of the percentages that the sector manages: if it wants to comply with the standards of the Paris Agreement, its annual emissions will have to be reduced at least 16% by 2030.

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Objective: reinvent cement. The sector and researchers are aware of these weak points and have been working on formulas that are more respectful of the environment for some time. The objective, not at all simple: to reinvent cement, to achieve a “green” material that allows us to continue using it in our constructions while reducing its negative effects on the environment. Efforts in that direction have been activated over the years, of course.

In 2021 the University of Tokyo introduced a variety of cement made with food scraps, a material that, they say, is more resistant. The Japanese institution has also developed a process that allows concrete to be made with old fragments of material. Before, a team from Taipei had shown as waste from agriculture and aquaculture can also be used to replace coarse particles and binders in green concrete.

In this effort to obtain cement with less impact, a firm from Colorado (USA), Prometheus Materialsannounced just a few days ago that it is working with microalgae-based cement to build masonry blocks. A good example of the interest it arouses in the industry is that it has just closed a round of financing eight million dollars. Recently, a team from Washington also proposed making cement by reusing old masks.

Concrete also pollutes, and that is why Amsterdam has proposed that 20% of its buildings be made of wood

The great challenge: scale production and pave the way. Developing new varieties of green cements, more respectful of the environment, is not the only challenge that researchers and industry have ahead of them. Making it is only the first step. as pointed out Popular Science (Popsci), there are other important and equally crucial challenges, such as costs, scaling up production or convincing the industry to take the plunge and change conventional cement for new alternatives.

“Completely changing the way we use cement would require many fundamental changes in our industry,” explains to Popsci Sohan Mone, Engineer: “The whole infrastructure is geared towards how cement currently works, from how we install it to how we transport it, everything.” One of the great challenges that cement companies and construction companies would have ahead of them is to demonstrate that the new alternatives meet the demanding safety standards. “We’re very regulated, rightly so, and we’re not very free in what materials we can use.”

Pictures | Jon Evans (Flickr) Y Bex Walton (Flickr)

From Tokyo to Madrid, passing through New York, Guadalajara, Vigo or Abu Dhabi. It doesn’t matter which city you look…

From Tokyo to Madrid, passing through New York, Guadalajara, Vigo or Abu Dhabi. It doesn’t matter which city you look…

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