Green cement could change the construction game—but will builders actually use it?

Green cement could change the construction game—but will builders actually use it? thumbnail

Concrete ranks second in the world’s most used materials. Concrete is the second most used material in the world.

The building material is water, coarse aggregates like sand, gravel, and a binding agents. This is where cement, a product that emits high levels of carbon emissions, comes in.

According the International Energy Agency, the cement industry is the third-largest consumer of industrial energy in the world, accounting for seven percent of all industrial energy use. It is also the second largest industrial emitter of carbon dioxide and responsible for seven percent global emissions. Most emissions occur when raw materials, typically clay and limestone, are heated to more than 2500 degrees Fahrenheit to become the super-strong binding material. Roughly 600 kilograms of carbon dioxide are released per ton of cement produced.

But, cement is becoming more popular considering the environmental impact of traditional cement. A recent example was created by Yuya Sakai and Kota Machida at the University of Tokyo. They made cement from food waste. food waste has been used in cement alternatives prior to ,, but Machida & Sakai created the first cement made entirely of food waste.

The duo spent months mixing food scrap with plastic to make the materials stick together. They finally found the right temperature and pressure to make cement using only food waste. Using a “heat pressing” strategy typically used to make construction material from wood powder, they mixed the food waste powder with water and pressed it in a mold heated to 350 degrees Fahrenheit. Researchers claim that the cement has a tensile strength or bending strength three times higher than ordinary concrete.

[Related: Tech to capture and reuse carbon is on the rise. But can it help the world reach its climate goals?]

” The most difficult part was that each type food waste requires different temperatures, pressure levels, Sakai stated in a press release. They used tea leaves, orange, onion, and coffee peels, as well as coffee grounds, Chinese cabbage, and leftovers from lunch boxes.

” Our ultimate hope is for this cement to replace plastic and cement products that have worse environmental impacts,” Machida stated in an interview with the AP this month.

Researchers and engineers have been working for years to reduce concrete’s carbon footprint. In 2021, scientists from the University of Tokyo created a process for making concrete that reuses old concrete products (which can often go to waste), heats materials at lower temperatures, and captures carbon dioxide out of the atmosphere.

In 2019, researchers from the National Taipei University of Technology in Taiwan and the Water Resources Department in India discovered that natural wastes from agricultural and aquaculture farming could partially replace coarse materials and binding materials in green concrete. There are many other options, and even though they are still in development, these innovations bring building materials closer towards reducing carbon emissions.

But it can be difficult to convince companies to scale up food waste cement to use for building construction, Sohan Mone, a structural engineer at Ferrovial, says.

” To change the way cement is used, we would need to make a lot of fundamental industry changes,” Mone states. “All of the infrastructure is geared towards how cement currently works, from how we install it to how we transport it, everything.”

That doesn’t mean it can’t be done, or that it isn’t worthwhile, Mone says. However, one technology will not solve all problems in the building industry.

Mone is concerned that cement producers and construction companies must ensure that all materials meet safety and performance standards. Concrete is used in large infrastructure projects. Concrete uses rebar-steel to reinforce cement. Concrete acts as porcelain by itself, without any structural support. Although ceramic objects such as toilets and sinks can withstand compressive loads, it is not as strong as concrete.

” When you apply a shearing force like tension or bending, [cement used on its own] shatters,” Mone states.

Using food cement or cement substitutes in concrete for more complex and building-intensive purposes would require safety and durability testing, Mone states. The industry regulators and contractors would need to be convinced that it is viable.

” We are heavily regulated, and rightly so. We also have limited options in terms of the materials we can use,” Mone stated. Mone stated that these structures can last hundreds of years. It’s still not clear how they will perform in the environment. There is always the fear that you won’t know how something new will react. And concrete itself needs a lot of maintenance.”

[Related: Pollution kills 1 in 6 people worldwide.]

Green materials are also expensive, which Mone states makes it difficult for companies to use them. It’s more common for developers to choose the most cost-effective plan when constructing large projects. Switching to green cement may be worth it, especially as concrete use rises in developing countries. Also, other countries are updating their infrastructure.

Global cement production could increase by as much as 23 percent by 2050, the Mission Possible Partnership reported in their Concrete Action for Climate plan. Concrete and cement are shaping the built environment. Their impacts will also impact our climate future.

The cement industry will need to decrease its annual emissions by at least 16 percent by 2030 to meet the Paris Agreement on climate change standards. Researchers argue that cement and concrete are crucial for future development and that reducing emissions will be the fastest way to reduce carbon and improve the environment.

” Given the urgency of this challenge and the historical time it took for technology systems to evolve historically, a significant push will be required to get the next generation low-carbon cements onto the market. Not all will succeed, but those that do could have significant decarbonization potential,” Chatham House, a policy institute, wrote in their 2018 Making Concrete Change: Innovation in Low-carbon Cement and Concrete report.

The pace of building cities and repairing infrastructure is not slowing down. However, revitalizing the built environment does not have to have a large carbon footprint due to new developments in greener materials.

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