A more sustainable cement is ready for the construction of the future

A new material developed by EPFL could revolutionize concrete production and save 500 million tonnes of CO2

Cement, a concrete and sustainable solution from EPFL
EPFL researchers have found a solution to reduce emissions during concrete production (Photo: Stefan Wermuth/LC3 Project/EPFL)

Every year, for each living person on Earth, approximately 4 tons of concrete are produced. The cement, which is used as a binding component for its production, thus alone represents the8 percent of emissions global of CO2.

The impact of concrete, in terms of emissions and resource consumption, is significant enough to represent a crucial challenge to the health of the planet. This is a particularly difficult task, since the need to reduce theclimate impact of concrete must deal with the needs of growing economies, which require new constructions and infrastructures.

Thus, the Building Materials Laboratory of Federal Polytechnic of Lausanne (EPFL) has studied a sustainable alternative consistent with the ever-increasing demand for building materials globally: it's called LC3 (“Limestone Calcined Clay Cement”) is already produced in various factories and allows emissions to be reduced by 40 percent compared to traditional cement.

An unforeseen research building in Dübendorf
Yes in Bavaria to the most sustainable noise barrier in the world

A more sustainable cement with less clinker
Professor Karen Scrivener, head of the Construction Materials Laboratory of the Faculty of Engineering of the Federal Institute of Technology in Lausanne which developed LC3 (Photo: EPFL)

Cement, Karen Scrivener's long research at the Polytechnic University of Lausanne

Karen Scrivener, head of the Construction Materials Laboratory of the EPFL Faculty of Engineering, studies the concrete for forty years. We build a lot with concrete, yet we still know too little about it. “It seems so simple: we mix a gray powder with water and a stable building material is ready”, explained the British scientist in an interview given last year. In the production of concrete, however, “complex chemical reactions occur”, which need to be investigated further.

In her long academic career, the researcher has done much to fill these gaps, focusing on improving the mechanical and environmental properties of concrete: as part of global efforts for reduction of greenhouse gas emissions, systematic work on concrete is more important than ever.

Scrivener and her multidisciplinary team at EPFL, together with industrial and research partners, have finally found a brilliant replacement for “traditional” concrete: it is the Limestone Calcined Clay Cement, abbreviated LC3, a calcined clay that does not emit CO2 and cooks at only 800 degrees centigrade (compared to 1.450° C for the classic process).

Zero emissions and a better quality of life: “That's Smart City”
Vollebak Island: the self-sustaining island for humanity of the future

Sustainable concrete: the EPFL recipe
We have been using concrete for centuries, but we still know little about it: what seems very simple hides very complex chemical reactions (Photo: Envato)

Cement and CO2 emissions: the real solution is to contain clinker

Il cement, the binding component of concrete, is responsible for 8 percent of global greenhouse gas emissions, and is the second most exploited commodity in the world after water. Concrete is anything but planet: to produce one ton, approximately one ton of CO2 is emitted. The production process and ingredients have remained the same as two hundred years ago.

Investigating further we discover that the clinker (basic component for Portland cement, the most used) constitutes on its own 90 percent of overall emissions due to the production of concrete: the generation of this material has in fact a very high carbon intensity, which means that, while on the one hand it requires fuels with a high energy content (fossil), on the other hand it emits a large amount of carbon for the energy consumed.

The chemical reaction of calcination, which gives the clinker its binding properties, is alone responsible for 60 percent of the emissions linked to the production of concrete: eliminating the clinker from the cement would make it possible to eliminate these emissions, but this way is technically almost impossible, explains Karen Scrivener .

However, there is an effective solution for significantly reduce emissions CO2: limiting the percentage of clinker in the cement, replacing it with other materials such as fired clay, allows emissions to be reduced on both fronts, limiting the CO2 produced by the chemical reaction and minimizing the quantity of fuel needed to process the cement.

Sustainable construction: the… mushrooms protagonists among the green materials
Architecture at the service of the climate and man: here is the Klimatorium

Sustainable and economical cement for the construction of the future
Calcined clay cement made at EPFL is less permeable to water and salt, therefore more durable than Portland cement, and can be produced at a lower cost (Photo: Envato)

LC3 is born, the sustainable and economical cement that will make the difference

In the long search for ideal substitutes for clinker, Scrivener and its team have achieved important results with Limestone Calcined Clay Cement, a calcined clay that can be fired alone 800 gradi Celsius and which, unlike the limestone used for clinker, does not emit CO2 when heated.

The Limestone Calcined Clay Cement, or LC3, cooks at much lower temperatures than traditional cement, which reduces the amount of fuel needed and allows us to hypothesize the use of cleaner energy sources like electricity, a non-viable option for clinker.

By replacing half of the clinker, LC3 can reduce CO2 emissions by approximately 40 percent compared to conventional concrete. The concretecalcined clay it is also very functional: it is less permeable to water and salt, therefore more durable than Portland cement, and can be produced at a lower cost. Because it requires less energy and uses a widely available clay, the production of LC3 it can cost up to 25 percent less compared to conventional concrete.

This is not about demonizing concrete, on the contrary. In itself, concrete has a lower CO2 footprint than all other building materials: it is very durable and therefore has a positive life cycle. The problem, if anything, is that we produce an impressive quantity of them. And we can't stop doing it.

ReFuel is the star of "Clean energy and sustainable mobility"
Sustainable construction starts with public toilets: the project in Sri Lanka

A sustainable cement for the development of the South of the world
A view of the city of Lagos, Nigeria: most of the construction in the coming years will be concentrated in emerging economies such as those of African countries (Photo: Envato)

LC3: a sustainable solution also (especially) for the South of the world

We produce every year 30 billion tons of cement-based material, “a huge figure and significantly higher than all other materials that humans use together”, recalls Scrivener.

On the other hand, "Stopping concrete construction is not an option for emerging economies": the Wood it can satisfy a maximum of 10 percent of demand and does not represent a solution for the South of the world. “There is not enough space for the forest that would be needed”, explains the researcher, “and we don't even have 30 years to grow enough trees".

What you need is one practical and concrete solution, which allows reduce emissions from cement production, without giving up the qualities that have made it the most used building material in the world over the centuries. For example, using a material, clay, widely available worldwide (including countries, such as those in Africa, which cannot count on significant limestone resources).

The production of LC3, cheaper and less wasteful than that of clinker, has already started in numerous factories around the world: Argos Cementos in Colombia produces 2,3 million tonnes of LC3 cement per year, and Holcim in Canton Zug has announced it will produce 500.000 tonnes annually.

For every ton of calcined clay produced, 600 kilos of CO2 are saved. By the end of 2023, LC3 will have already saved 15 million tons of CO2. If the cement industry widely adopted the use of Limestone Calcined Clay Cement, between now and 2030 we would be able to avoid 500 million tons of emissions CO2.

So Big Data will make our concrete much more... green
Sustainable architecture in Vietnam: the dream waterfront

An Introduction to Sustainable Concrete Limestone Calcined Clay Cement or LC3 (in English)

LC3, the sustainable cement created by EPFL
Concrete cannot be replaced. But can it be more sustainable? The solution from EPFL researchers (Photo: Envato)