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What is the Carbon Footprint of Concrete?

EcologyConstruction

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Stephanie Safdie

updated Jan 24, 2024

US Copywriter at Greenly

When we take a look at major cities such as New York, London, and Tokyo – the first thing that may come to mind about the ecological impact of these cities may be their infrastructure or the excessive emissions created by the mass transportation or car usage, but the carbon footprint of concrete isn’t usually the first one that comes to mind.

Major cities in the world are largely composed of concrete, but did you know that the carbon footprint of concrete is bigger than most people think?

In this article, we’ll explain what concrete is, why big cities use concrete, the carbon footprint of concrete, and some viable alternatives to concrete.

What is concrete?

Concrete is a material which consists of both solid and chemical substances, such as sand, gravel, cement, and water in order to create a smooth or rock-like consistency.

“ Many cities in the world make use of concrete, sometimes being referred to as, “concrete jungles” – such as New York City, Los Angeles, London, Beijing, Paris, Washington D.C., Chicago, and Tokyo. ”

When we think of concrete, our mind usually goes to the material found on sidewalks or the outer surface of a building or wall – but concrete is used more often than we realize.

Concrete is commonly used for:

Paving sidewalks;
School playgrounds;
Exterior surfaces of buildings or walls;
Parking lots or various structures found nearby;
Foundation for larger buildings found in big cities;
Wastewater treatment facilities.

People oftentimes get concrete confused with cement, however – the two are not the same. Concrete is usually composed of sand, gravel, and cement – whereas cement is solely a binding agent composed of resources such as limestone and clay. In short, concrete can’t exist without cement – but cement can exist without concrete.

👉 Did you know? Out of the 300 square miles that make up New York City, almost 1.7 trillion pounds of concrete are used to make up much of the pavement and buildings found in the city that never sleeps.

Why is concrete important to society?

Concrete is used often and remains important to society seeing as it can help to benefit both the environment and the economy when employed correctly – such as help to increase energy efficiency and boost the economy through job creation.

“ Much of our modern world would not be possible without the use of concrete, seeing as many major cities across the world have built their worlds off of concrete – where population density is greater, meaning that many humans rely on concrete in their daily lives. ”

Some of the additional benefits of concrete include:

Provides safe and affordable infrastructure;
Flexibility to be used for various purposes: such as for schools, hospitals, public buildings, and even infrastructure for transportation;
Concrete can be energy efficient;
Can help to boost the construction industry and overall economy;
Helps to inspire new designs for modern buildings and infrastructure;
Concrete has the ability to absorb excess heat and help to reduce the energy consumption of buildings;
Allows for more jobs to be created within the concrete, construction, and infrastructure industries.

However, the overarching importance of concrete is that it allows us to curate a more functional society.

For instance, without concrete, we wouldn’t be able to build bridges – and without bridges, many of us would be forced to take boats or ferries to cross bodies of water.

👉 Ultimately, concrete has allowed for greater convenience in society – with the majority of modernized design being impossible without the use of concrete.

What is the environmental impact of concrete?

Even if concrete has proven essential and affordable to accommodate modern life, the carbon footprint of concrete has proven to be massive – seeing as concrete contributed to 8% of global emissions in 2021.

“ Concrete, while versatile and able to stand the test of time – is proving itself to be a problem in our world as concrete emits a massive amount of carbon dioxide emissions. ”

It isn’t as much the actual make-up of concrete that contributes to the carbon footprint of concrete, but how commonly it is used. From buildings, to bridges to tunnels – around 4 billion tons of concrete were produced in 2021 alone.

In fact, the production of concrete is more carbon intensive than the aviation industry – with air travel only accounting for 2% of global emissions in 2022 compared to the 8% of emissions from concrete in 2021.

However, it’s also the manufacturing process of cement itself, compulsory to be used in concrete, which generates much of the excess emissions. This is because clay and limestone, the materials required to produce cement, need to be heated over 2,500 degrees Fahrenheit (around 1,371 degrees Celsius) in order for it to work as a binding agent in cement.

“ As a result, each ton of cement can equate to nearly 1,400 pounds of carbon dioxide emissions. ”

In addition to all of these, the carbon footprint of concrete can be attributed to:

Water Usage – The production of concrete requires water in order to mix and cure the concrete. This means that major construction sites may go through excessive water resources that could serve as viable drinking water.
Air Pollution – When manufacturing cement, additional pollutants like sulfur dioxide and nitrogen oxide are emitted – both of which contribute to air pollution.
Excess Waste via Construction – Concrete can indirectly contribute to excess carbon emissions, as concrete can create demolition waste and concrete debris. While it is possible to try and recycle concrete, those working in the construction industry usually do not think or even attempt to do this for the sake of time efficiency and remaining productive.
Depletes Resources – Concrete may remind you of “rock” for a reason – it relies on sand and gravel to be made. However, sand is considered a natural resource – and helps to protect coastlines vulnerable to erosion or coastal damage. This means that continuing to manufacture concrete at the scale we currently do can indirectly make the impact of natural disasters worse.
Emissions via Transportation – Think about it: most of the concrete you are seeing being implemented onto new sidewalks, roads, or buildings is not being made right before your eyes. The concrete is being manufactured elsewhere, and then has to be transported. This means concrete contributes to excessive greenhouse gas emissions.
Additional Energy via Repairs – It’s already an intensive process to produce concrete, but what happens when there’s a crack in the ceiling – literally? Concrete is usually prone to cracking, meaning that repairs will be necessary – which means further production of concrete is necessary in order to move forward with those repairs. This demonstrates a never ending cycle of intensive energy usage that concrete has created.

👉 Evidently, concrete is a major contributor to global emissions, meaning if we curb emissions, we need to create more sustainable alternatives to concrete – some of which are already in the works.

What are the other downsides to concrete besides the carbon footprint of concrete?

There are several negatives to the use of concrete, such as how long it takes for concrete to cure and hinder future creativity in construction and infrastructure with the easy accessibility of concrete.

“ The carbon footprint of concrete is one of the major reasons to avoid using it, but there are several other reasons which prove that concrete may not be the most suitable choice for long-term infrastructure – especially as we seek more sustainable choices in the midst of climate change. ”

Here are some more downsides to the use of concrete:

Reduced Room for Future Innovation – Concrete is an affordable and reliable material, which is one of the main reasons why it is used as commonly as it is. However, the issue with this is that it can prevent those working in design or construction from getting creative in developing new alternatives to the use of concrete. As long as concrete remains cheap and available, there is less incentive to search for alternatives to concrete.
Low Tensile Strength – While concrete is very dense and durable, its tensile strength is weak – which is why overtime, you are bound to see cracks in concrete walls overtime that will need repairs. This can also result in a lack of insulation and increase energy consumption, as residents will use more heat or air conditioning to compensate.
Long Curing-Time – Concrete may be the cheaper option, but it isn’t the fastest – seeing as it takes nearly 28 days for concrete to fully set. This is why you may see a part of the sidewalk or street blocked off for long periods of time, even when it appears on the outside that the road work repairs are finished.
Out of Style – It is also important to note that as modern design begins to become the desired “look” for many architects and interior designers – that concrete may not have the flexibility or aesthetics desired by designers.

👉 Concrete has demonstrated that it has negative qualities in addition to its environmental impact, which begs the question – are there any alternatives in order to reduce the carbon footprint of concrete?

What are some alternatives to concrete?

Unbeknownst to most, there are several alternatives to the use of concrete – such as aircrete, hempcrete, and green concrete.

One of the major projects in the works to reduce the environmental impact of concrete is to develop “carbon-neutral” concrete – which would require replacing over a third the cement usually used in concrete with magnesium and silica. This would help to reduce the carbon footprint of concrete seeing as one of the most carbon intensive parts to concrete is the ecological impact of cement.

Aircrete – This type of concrete, which is composed of cement, lime, water – creates a chemical reaction that forms air bubbles, hence the name “aircrete” – and has a lower carbon footprint than classic concrete.
Green Concrete – This type of concrete seeks to make use of materials that would otherwise be discarded. Ultimately, this type of concrete helps to reduce construction waste and usually has a better life-cycle than classic concrete.
Hempcrete – Hempcrete is made of biocomposite materials – such as hemp hurds, hemp fibers, lime, and sand. This makes it more lightweight than classic concrete without compromising on insulation, helping to reduce the carbon footprint of concrete.

“ In addition to these modified and more eco-friendly versions of concrete – there are other ways to help reduce the impact created by concrete, especially in cities. ”

For example, studies have shown that much of construction which resorts to the use of concrete could be replaced with the use of timber. However, the downside to this is that timber is more flammable than concrete – and with extensive wildfires such as those that occurred in Maui last summer, it doesn’t make a compelling argument for timber to replace concrete.

However, there are still more counter actions that can be taken for cities and construction companies wary of shying away from the use of concrete. For instance, cities like New York can try to take after European cities such as Paris and strive to create more green areas and parks, as this can help to absorb more carbon dioxide in bustling cities.

Ultimately, the push for discovering new alternatives to concrete has never been more important as the world begins to take climate change more seriously – and luckily, there are multiple alternatives for the world to reduce the carbon footprint of concrete: together.

What about Greenly?

If reading this article about the carbon footprint of concrete has made you interested in reducing your carbon emissions to further fight against climate change – Greenly can help you!

It can be challenging to fully understand the carbon footprint of concrete amongst many other activities and materials in your business, but don’t worry – Greenly is here to help. Click here to schedule a demo to see how Greenly can help you find ways to improve energy efficiency and decrease the dependency on fossil fuels in your own company.

Greenly can help you make an environmental change for the better, starting with a carbon footprint assessment to know how much carbon emissions your company produces.