Concrete is the world’s third largest emitter of greenhouse gases

If all the concrete used in the world were considered as a country that produces greenhouse emissions, it would be the third most polluting, behind China and the United States.

Why is it said that concrete and cement have the worst carbon balance in the industrial sector?

, about 150 tons per second: 14,000 million cubic meters of concrete are used each year, according to the World Cement and Concrete Association (GCCA), which groups together the main players in the sector (the Swiss Holcim, the Mexican Cemex, or the Chinese CNBM, among others).

Construction represents 13% of world GDP.

The production of cement, a key element of the concrete mix, (CO2), according to the GCCA, three times more than air traffic.

“It is more than the emissions of the whole of the European Union or India, behind those of China and the United States”Valerie Masson-Delmotte, paleoclimatologist, co-chair of a UN group of climate experts, told AFP. Something that does not seem to be changing, with increasing urbanization in Asia and Africa.

How does cement produce CO2?

Cement, the “glue” of the granules and sand that make up concrete, is formed mainly by clinker, a product that is obtained by calcining limestone and clay in a kiln at 1,400 degrees Celsius. When burning it,.

Producing a ton of cement releases almost a ton of CO2.

This important chemical reaction, which has hardly changed since the current formula for cement was invented two hundred years ago, accounts for the remaining 30% comes from the energy consumption of the kilns when burning the limestone.

How to decarbonize construction?

The global concrete industry, which announced its goal of achieving carbon neutrality by 2050 last year, recently explained how it would achieve its emissions by 2030, which will prevent 5 billion tons of CO2 from being released in that period.

The sector is confident that new carbon sequestration technologies will allow it to advance its emission reduction targets by 2050.

It is also committed to increasing the. Other clues go through converting concrete into a “green” product: substituting fossil fuels from cement kilns with waste and biomass (animal meal, reused wood …).

In terms of carbon capture and storage, this industry plans to install “by 2030, 10 industrial-size structures to capture carbon.”

Large companies such as the Chinese CNBM (China National Building Material Company) promised to “play a role” in the decarbonization of the industry.

Emerging companies also want to participate in this project: the American company Solidia proposes In Canada, CarbonCure is already working on the injection of liquefied CO2.

But above all, the industry is committed to the commercialization of new “green” cements that replace clinker with reused materials.

The GCCA notes that in Great Britain, the reuse rate is 26%. France adopted a new standard for low-carbon cements in May.

What is green cement? What about low-emission cement?

At the moment, these types of products are in the hands of emerging companies since traditional cement industries are lagging behind in the modernization of their production instruments, with more important investments in quarries.

One of the companies that have advanced the most is the French Hoffmann Green Cement, which manufactures clinker-free cement, based on industrial waste such as biomass fly ash or clay waste.

And although the extra costs in construction reach 25 euros (almost 30 dollars) per square meter, this French company does not stop receiving orders.

“The cement industry plans to reduce its emissions in 2050 but with our proposals it can be done today”, explains Hoffmann Green Cement founder Julien Blanchard to AFP.

The challenge is one of size: “Three out of every four infrastructures that we will see in 2050 have not yet been built”, warns the Secretary General of the United Nations, Antonio Guterres.

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