The construction industry is confronted with pressing environmental challenges, specifically regarding high levels of CO2 emissions and the depletion of natural resources. Concrete, a material extensively utilized in construction projects, contributes significantly to these concerns due to its alarming carbon footprint. In response to this issue, innovative solutions have emerged in the form of sustainable concrete alternatives that aim to mitigate the environmental impact of traditional concrete. Let’s explore 5 notable sustainable concrete options that offer promising solutions for greener construction industry.
Concrete is one of the most commonly used construction materials worldwide, appreciated for its durability, strength, and versatility. In fact, two-thirds of all structures on the planet are made of concrete. Traditionally, concrete production requires 80% aggregates (gravel and sand), 11% cement, and 9% water.
However, while being the most commonly used building material, it is also a significant source of greenhouse gas emissions.
New types of concrete are therefore being developed to combine the material’s efficiency and durability with environmental sustainability.
1/ Recycled Concrete
By incorporating recycled aggregates obtained from demolished structures or industrial by-products into the concrete mix, recycled concrete reduces the demand for virgin materials and minimizes waste. This approach helps decrease CO2 emissions associated with traditional concrete production while providing second life to materials that would otherwise end up in landfills.
In France, SEQENS, a subsidiary of the Action Logement Group, and HOLCIM, a construction materials producer, have partnered to construct a residential building using solely recycled concrete. Located just outside Paris, the project is set for completion in 2024. The construction materials for the building, totaling 2,200 tonnes of concrete, have been exclusively supplied by Lafarge, a renowned French cement manufacturer. This innovative initiative marks a significant milestone as the world’s first structure to be constructed entirely from 100% recycled concrete.
In an interview, Mouloud Behloul, Director of Innovation and Sustainable Construction at Lafarge Cement France told DirectIndustry:
“This represents a significant technical achievement. The clinker, which is the active base of cement, the aggregates, and the sand come from construction and demolition waste, unused hardened concrete from construction sites, and demolition site concrete. The water used is also recycled and comes from the process water circuit. We have developed a specific recipe using these different recycled materials to achieve the same results as traditional concrete.”
2/ Wood-Based Concrete
Is wood-based concrete the new wonder building material? In any case, it’s made of cement, water, and wood (80%) and is expected to be an alternative to many carbon-intensive materials.
French company CCB Greentech develops the TimberRoc® technology that enables precast load-bearing walls and slabs made of wood-based concrete.
CCB Greentech’s wood-based concrete contains 80% of wood by density. And according to the company and an FDES (Environmental and Health Data Sheet), their material has a negative carbon balance. In an interview with DirectIndustry, Caroline Gérard, Marketing Director said:
“During their growth, trees absorb C02, thanks to photosynthesis, and store it in their wood cells. As our wood is encapsulated in cement for the whole life of the product, it does not release any C02. So by using pulpwood to produce wood-based concrete, we trap this carbon in the walls, slabs… And as the cement we use required fewer C02 emissions than the wood we use absorbed, our carbon balance is distinctly negative. We can go up to -70 kg of CO2 emitted per m², depending on the thickness of the wall and the construction method.”
3/ Low-carbon Concrete
Low-carbon concrete is concrete in which the associated CO2 emissions during production are reduced. In concrete manufacturing, it is the limestone that needs to be heated to very high temperatures that is the main source of carbon dioxide emissions. The challenge is to replace a portion of this limestone.
To achieve this, it is possible to use residual minerals from the industry, such as blast furnace slag or clay. Depending on the proportions used, the concrete can have a carbon footprint up to 70% lower than that of traditional concrete, without compromising technical performance.
Vinci Construction made a conscious decision for the Paris 2024 Olympic Games nautical stadium in Marseille, opting for sustainable practices and incorporating durable construction materials including low-carbon concrete. During our visit to the site at Roucas Blanc Bay, we had the opportunity to explore this innovative concrete firsthand.
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Researchers at Incheon National University in South Korea have created cement-based composites with conductive fillers that generate and store electricity through contact electrification. This innovative material could be used to construct buildings capable of harnessing energy from human motion, as well as wind and rain.
The study, published in Nano Energy, highlights the potential of this eco-friendly cement-based conductive composite to revolutionize construction and contribute to sustainable, energy-efficient smart cities.
In a statement, Prof. Seung-Jung Lee from Incheon National University explained:
“We wanted to develop a structural energy material that could be used to build net-zero energy structures (NZES) that use and produce their own electricity. Since the cement is an indispensable construction material, we decided to use it with conductive fillers as the core conductive element for our CBC-TENG system.”
5/ Edible Concrete
Researchers from the University of Tokyo in Japan have developed a groundbreaking method to transform food waste into highly durable and potentially edible cement. By drying and compressing food waste, such as Chinese cabbage, banana peels, and coffee beans, they have created a 100% biodegradable cement that exhibits exceptional strength.
Kota Machida, one of the researchers, has since created the company Fabula Inc and is the CEO. The patent application for this technology by the Institute of Industrial Science of the University of Tokyo is still pending.
According to the researchers’ calculations and strength tests, their organic concrete is four times stronger than traditional concrete, as explained on Fabula’s website:
“The bending strength of a material made from food waste of Chinese Cabbages is 4 times stronger than concrete. A 5 mm thin plate can bear 30 kg weight. It has the potential to become a construction material in the future.”