The big problem with cement, and how to fix it (2023)

Introduction

Concrete emits a ton of carbon. Here's how we get it to net-zero.

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Cement accounts for 8 percent of our global carbon emissions. It’s also an incredibly difficult material to do without: It’s the glue that holds together the rock, sand, and water in concrete. And concrete is the building block of the world: It’s in our buildings, our streets, our sidewalks, and our infrastructure. Aside from water, there’s no material on earth we use more of.

In order to get to net-zero CO2 emissions by 2050, we’ll have to address how we build and how we make cement. Because cement production is so closely linked to urbanization and development, China accounts for a vast majority of today’s cement-related emissions. Other countries with more development in their future will need to emit more emissions to produce cement, too. All that means the whole world needs to figure out how to create cement without the emissions. This video goes into the steps developed by researchers for how to get there.

Note: The headline on this piece has been updated.
Previous headline: Why cement is so bad for the climate

Further reading:

Here is a link to the Nature article that we based our key visual on. Two of the co-authors, Paul Fennell and Chris Bataille, appear in the video:
www.nature.com/articles/d41586-022-00758-4

I interviewed Brian Potter, who wrote this great article on how much concrete we consume:
heatmap.news/economy/the-planet-s-jaw-dropping-astonishing-downright-shocking-amount-of-concrete

Hannah Ritchie from Our World in Data wrote a great Substack clarifying the data on China’s cement emissions:
hannahritchie.substack.com/p/china-us-cement

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Content

Let's imagine a modest-sized skyscraper..

about 100 meters and 30 stories, tall.

A high rise.

This size was almost certainly built with concrete, which contains cement.

In.

This case, about 6,000 tons of cement.

Making that cement probably emitted about 4,600 metric tons of carbon into the atmosphere.

That's about the emissions from driving a car for 12 million miles.

Now.

Multiply that by all the buildings in the world.

Even that wouldn't capture cement's carbon footprint.

Think about the sidewalks.

We’re walking on.

Many of the streets.

You drive on.

A lot of our energy infrastructure.

Dams, power, plants.

All that cement production accounts for 8% of all global carbon emissions..

more than the aviation.

And the shipping industries combined.

Today.

Most of those emissions are due to China's, rapid development., In, just two years, China produced more cement than the US did in the entire 20th, century.

Other, developing countries will use a lot of cement as they build tall cities and infrastructure, too.

If.

We want to reach net zero in a few decades, we'll have to figure out how to build a building like this..

without emissions.

It'll, be hard, but there's, a way.

You're, looking at a typical cement plant.

One like this is currently operating in nearly every region of the world.

This rotating tube, a kiln.

And this tower, a pre heater are where all cement's emissions.

Take place.

About 40% of cement's emissions are a result of burning fuel to heat, the kiln.

It reaches around 1450 degrees, Celsius near the heat.

Source.

The preheating tower is where limestone, clays and other additives are dropped.

The 850 degree temperature.

Here causes limestone to release its stored carbon dioxide.

And those are the other 60% of emissions.

The.

First question about decarbonizing, cement is whether we can just use less concrete, altogether., We typically use up to 2 to 3 times too much concrete in design.

Architects and structural engineers just use lots of it.

It doesn't hit the bottom line.

And it makes the thing more reliable and they're less likely to get sued and kill people.

And what have you.

In a building, concrete is valuable for its compressive strength:, its ability to hold up under a lot of weight.

So it's hard to substitute its use in places like foundations and columns.

But elsewhere.

We should minimize it.

I was in the new Parliament building in Scotland.

And it was obviously designed with greenhouse gases in mind.

Concrete was only used where needed.

Steel was only used where needed.

And.

They used laminated wood for the roof for a lot of structural materials things that weren't load bearing.

Carbon.

Conscious design can certainly chip away at cement's, emissions.

But, replacing concrete altogether won't be possible in the near term.

So cutting down on excess concrete can cut emissions on our high rise by roughly 26%, according to one analysis.

We'll have to do more.

And the next place to start is how cement is made.

Looking at the 40% of emissions that go into firing the kiln is one place to start.

Typically, cement plants use coal or petroleum coke or natural gas to heat the kiln to 1450 degrees, Celsius.

You could electrify that, but it's really hard to achieve that high of a temperature with electric heat.

Though.

Some startup companies like this Finnish.

One are trying.

Until.

We get there cement plants have started to just burn different.

Things.

The high heat makes cement plants, a good place to incinerate industrial waste, trash, or used tires.

The limestone, basically scrubs out any nasties that are produced in the flame here..

and stops them being emitted into the atmosphere.

Switching fuels can cut emissions by roughly 7%.

We've still got a ways to go.

So let's, look at the other way, cement causes emissions: The.

Chemical process.

This is the carbon released from the heated limestone.

Once.

It goes through the kiln.

It becomes a material called clinker:.

The key binding ingredient in cement.

And, cement binds together, the rocks and sand and water in concrete.

Cement is about 10% of concrete but accounts for a majority of its emissions.

So.

One strategy is to find a substitute for the clinker.

Startups have been in a race to develop a new kind of green cement that avoids clinker altogether.

But.

So far, nothing is as abundant and commercially viable as the limestone-based stuff.

And adjusting concrete.

Formulas takes a lot of time and safety testing.

For, good, reason., The events in Turkey recently.

There was a lot of substandard cement being used there.

And there was a lot of substandard building practices., In, North, America, clinker accounts for about 90% of cement due to safety standards.

But, North America is overly cautious compared to the rest of the world.

The average clinker-to-cement ratio, globally was about 72% in 2020.

That's made possible by clinker-like substitutes.

We could reduce the clinker ratio even more.

Experts, emphasized one new cement mixture that gets the clinker ratio safely down to 50% by supplementing it with more clay and unprocessed limestone.

So.

That’s with an existing technology that meets existing building codes.

That'll cut half the emissions from the cement and concrete industry.

These reductions will help in reducing emissions..., but until we find a scalable, zero-emission cement, any clinker production at all will inevitably have process.

Emissions.

Which brings us to the last piece of decarbonization.

The cement industry will need to use carbon capture and storage to get there.

There's.

No way around it.

This would mean capturing the carbon emitted from the heat and chemical processes here..

and storing it deep underground in a geologic deposit.

A.

Cement company in Norway is piloting.

One of the first cement plants in the world to capture carbon.

And, they'll store it under the North Sea in their oil and gas.

Deposits.

Some.

New companies are also finding a way to inject stored carbon back into cement and concrete during production.

This takes advantage of rock's, natural ability to reabsorb carbon.

And, potentially one day we may even see our built environment become a carbon sink, which we don't usually think about when we think about large concrete cities and large buildings and our roads and all of that.

So.

This is the scenario in which we get this building to net zero emissions., And.

The goal right now is to get there by 2050.

That requires us to start now and aggressively.

Especially in China.

The world's biggest producer.

But experts told me, there's, some good news, there.

So in the US.

The average age of a cement plant is about 34, 35 years., In, China, it's 15, which means that many of their plants are actually more energy efficient than the plants that we have here.

China uses less clinker in their cement than the global average.

And they have at least one carbon capture project in the works.

But there's, a long way to go.

Last year.

They pushed back their peak building emissions deadline from 2025 to 2030.

Changes to design in the concrete and cement processes will be the easiest to implement...

But carbon capture and storage is at very early stages., And, all this will be expensive.

It's estimated that the cement used in this building will cost somewhere between 70 to 115% more.

The cost of cement or concrete is a very small fraction of the overall cost of a project.

So it's relatively easy and cost effective for a government agency to commit to pay a little more for the material to absorb that green premium.

The US, Inflation Reduction Act is helping create a market for carbon capture and storage by increasing tax credits to $85 per metric ton of carbon stored.

For, a long time, heavy industries, like cement seemed like unsolvable climate problems., But today, we know how to fix them and we can't afford not to try.

Thanks for watching the video.

As.

A follow up to this one, I'd recommend checking out.

My coworker, Phil, Edwards’s, great video on the world's, tallest mass timber building in Milwaukee, Wisconsin.

He was able to film the building under construction.

And he gives a great explanation about how changing from traditional materials like steel and concrete to wood changes the entire building process.

Wood, probably can't, replace concrete in all the world's buildings.

One expert, I interviewed told me we'd probably have to triple the amount of wood harvested in order to scale it up and do that.

And that would come with its own environmental problems.

But.

Our big concrete problem requires a lot of different solutions and using wood.

When possible is definitely one of them.

And as you can see from Phil's video, it looks really cool, too.

FAQs

What is the problem with cement? ›

Problems with concrete include construction errors, disintegration, scaling, cracking, efflorescence, erosion, spalling, and popouts.

Can concrete be made without coal? ›

Cement cannot be made without “clinker,” an ingredient that produces emissions – even if fossil fuels are completely removed from production. The carbon dioxide emitted in this reaction is referred to as “process emissions,” since they would be created – even if the heat was produced without burning fossil fuels.

Is it possible to repair concrete? ›

Cracks in your concrete can be fixed using a sealant. The sealant is poured into the cracks and allowed to dry. You should always use a professional service to make sure the correct sealant is used and the correct color is maintained.

Are there any alternatives to concrete? ›

Alternatives made from recycled materials --- like ferrock, ashcrete, timber create, and hempcrete --- tend to require less carbon than concrete and also help to recycle waste materials like steel dust and chaff.

Will we ever run out of cement? ›

For many people reading this post, it is entirely possible you will be alive to witness a time when are out of practical sources of natural sand to use in construction. That being said, construction will not just stop once we have depleted our natural sources of sand—we will not just run out of concrete.

What is the most common concrete failure? ›

The two most common causes of failure are carbonation and chloride contamination of the concrete. Both of these lead to corrosion of the embedded steel reinforcement and as the steel corrodes it expands and exerts pressure on the concrete so that, eventually, the concrete cracks and spalls.

How many cement plants are in the US? ›

The U.S. cement industry is comprised of 106 cement plants (99 clinker-producing plants and 7 grinding facilities) operating just under 100 mmt of clinker capacity and roughly 126 mmt of finish grinding capability annually.

How can we save cement? ›

Right Way To Store Cement to Maintain its Quality

Store them in a windowless room to protect them against the moisture in the air. Avoid stacking more than fifteen bags on top of each other as there is a risk of the cement forming lumps.

What is the new material for cement? ›

Graphene, a wonder material invented in the UK early this century, is also coming into play. Experts at the University of Exeter have used graphene in concrete construction to create a new composite material that is twice as strong as traditional concrete and four times more water-resistant.

Does cement contribute to global warming? ›

Cement is the most widely-used substance on Earth after water. When mixed with water, it forms concrete that becomes the backbone of buildings, roads, dams and bridges. But the cement industry is responsible for about 8% of planet-warming carbon dioxide emissions — far more than global carbon emissions from aviation.

Can cement be made naturally? ›

But cement isn't some sort of naturally occurring organic material - it's manufactured through the chemical combination of 8 main ingredients during the cement production process. These ingredients are generally extracted from limestone, clay, marl, shale, chalk, sand, bauxite, and iron ore.

What are the alternatives to cement climate change? ›

Substituting materials such as volcanic ash, certain clays, finely ground limestone, ground bottle glass, or industrial waste products for conventional inputs can reduce the carbon footprint of cement by 7.70 to 15.56 gigatons between 2020 and 2050.

What is the best product to repair concrete? ›

Vinyl Concrete Patcher is ideal for making smooth repairs to crack or chipped concrete floors, sidewalks or steps. It has strong adhesive properties allowing it to be applied down to a featheredge. Quikrete 10 lb. Vinyl Concrete Patcher is made of a special blend of vinyl resin, fine sand and Portland cement.

Should concrete be cured? ›

Curing plays an important role on strength development and durability of concrete. Curing takes place immediately after concrete placing and finishing, and involves maintenance of desired moisture and temperature conditions, both at depth and near the surface, for extended periods of time.

What is the best product for repairing concrete steps? ›

QUIKRETE® Concrete Patching Compound is another option for small non-structural repairs. The pre-mixed acrylic material dries to a firm yet flexible finish. For repairs to concrete edges and corners QUIKRETE® Quick-Setting Cement should be used along with QUIKRETE® Acrylic Fortifier.

What is stronger than concrete? ›

Answer: Epoxy-based materials are different from standard concrete in a few ways. One of the primary things is the strength. When the epoxy is cured and hardened, it cures around 10,000 psi.

What is cheaper than cement? ›

Gravel is a whole lot cheaper than concrete, asphalt, or another paved surface.

What is the cheapest way to make concrete? ›

Working With Ready-Mix Concrete

And, if you mix it yourself, it's the cheapest way to make your slab. For most do-it-yourselfers, the best material for building a concrete slab is a ready-mix, crack-resistant concrete product. The wet mix is poured into a prepared wood form, then left to cure.

Can concrete last 200 years? ›

For large scale projects like buildings, concrete should last up to 100 years if it's properly cared for. Concrete projects that experience more wear-and-tear like sidewalks and driveways have an expected lifespan of about half that—50 years.

Why cement is not used in USA? ›

There are a few reasons why US homes are made of wood and bricks instead of concrete. The first reason is availability. The USA has vast forests to supply building materials. Second, history plays a large role in how people build their homes, as does American culture and style.

Can concrete last 1000 years? ›

Modern concrete—used in everything from roads to buildings to bridges—can break down in as few as 50 years. But more than a thousand years after the western Roman Empire crumbled to dust, its concrete structures are still standing.

What is the lifespan of concrete? ›

What is the maximum life of modern concrete? Generally, for large infrastructures, the lifespan of modern concrete is about 100 years if properly maintained.

What damages concrete most? ›

Corrosion of reinforcing steel and other embedded metals is the leading cause of deterioration in concrete. When steel corrodes, the resulting rust occupies a greater volume than the steel. This expan- sion creates tensile stresses in the concrete, which can eventually cause cracking, delamination, and spalling (Figs.

Which concrete lasts the longest? ›

Roman concrete has mostly stood the test of time. The Pantheon for example was dedicated in 128 CE and has the world's largest unreinforced concrete dome. Today, it's still intact.

What state has the most cement? ›

Cement production in the U.S. amounted to an estimated 92 million metric tons in 2021. Texas, Missouri, California, and Florida were the leading states in terms of cement production in 2021, having accounted for almost 44 percent of U.S. cement produced that year.

What state uses the most concrete? ›

Texas was the leading destination of US cement shipments year-to-date accounting for 16% of US cement consumption. Three of the top five 2018 single family housing markets, measured by permit activity, are in Texas in 2018.

Where is the largest cement plant in the US? ›

The World Record Academy certified a cement plant in Alpena, Michigan, as the “World's Largest Cement Plant.” The location, named Lafarge Alpena, produces more than 2.4 million metric tons of cement annually.

How can we improve the quality of concrete? ›

The compressive strength of concrete can be increased by:
  1. Including admixtures.
  2. Adjusting the cement type and quantity.
  3. Reducing the water/cement ratio.
  4. Utilizing supplementary cementitious materials (SCMs)
  5. Altering the aggregates - type and gradations.

What are three concrete steps you could take to reduce your global footprint? ›

Then, incorporate these suggestions to reduce your ecological footprint and make a positive impact!
  • Reduce Your Use of Single-Use, Disposable Plastics. ...
  • Switch to Renewable Energy. ...
  • Eat Less Meat. ...
  • Reduce your Waste. ...
  • Recycle Responsibly. ...
  • Drive Less. ...
  • Reduce Your Water Use. ...
  • Support Local.
Apr 27, 2017

How can we make concrete more sustainable? ›

Thus, in order to make concrete more sustainable one may work along one or more of the following routes; 1) Replacing cement in concrete with larger amounts of supplementary cementing materials (SCMs) than usual, 2) Replacing cement in concrete with combinations of SCMs leading to synergic reactions enhancing strength, ...

How can we prevent concrete from failing? ›

How to Avoid Concrete Failure
  1. Avoid trapped air. Trapped air bubbles in concrete can cause it to fail. ...
  2. Don't overload concrete forms. ...
  3. Always use good quality raw materials. ...
  4. Use water treated with low levels of dissolved sulphate. ...
  5. Don't use high-silica aggregates in areas with high humidity. ...
  6. Hire the professionals.
Oct 28, 2021

What materials make concrete stronger? ›

You can add more Portland cement to bagged concrete to make it stronger. You can also add hydrated lime. To make the strongest concrete, the sand should be sourced from volcanic lava that has a high silica content.

What chemicals are used to cure concrete? ›

There are 3 main types of curing compounds – PVA based, hydrocarbon and acrylic. These type of compounds typically form a temporary film over the surface. They will naturally begin oxidising after 6 – 7 days and will leave the surface after 28 days, allowing after-trades to be applied.

What chemical increases concrete strength? ›

Accelerating concrete admixtures are used to increase the rate of concrete strength development or to reduce concrete setting time. Calcium chloride could be named as the most common accelerator component; however, it could promote corrosion activity of steel reinforcement.

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