<aside> 💡 Meeting the Paris agreement is not possible without reducing emissions from cement production: cement is responsible for 8% of global GHG emissions and production is increasing.

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<aside> 💡 A lack of innovation isn't the problem: Alternatives to high GHG emitting cement are already available, it is regulations that have been slowing down widespread adoption.

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<aside> 💡 Industry standards favor high emitting cement: A new cement might be just as strong as Portland, but it won't show in the tests because it takes longer to develop those properties and all concrete is tested at 28 days (where portland cement is at full strength).

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Cement

Cement, a binder material used in the construction industry, is responsible for 8% of global GHG emissions. Global production of cement was 5.17 billion tonnes in 2020 (up from 1.6 billion in 2000) and is expected to hit 6.08 billion tonnes by 2026.

"All the plastic produced over the past 60 years amounts to 8bn tonnes. The cement industry pumps out more than that every two years." - The Guardian, 2019

It is estimated that every 1000 kg of cement produced emits between 730-990 kg of CO2.

More than half of cement emissions come from clinker production. Clinker is the binding agent in cement and is produced by heating limestone and clay until they liquefy (1400°C-1500°C). This process is so emissions heavy because the heated limestone itself releases CO2.

<aside> 📌 Clinker emissions = 50% CO2 released from limestone + 40% burning fuels to heat limestone + 10% mining and transportation.

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Concrete

The most common use of cement is to make concrete, which is the 2nd most used material in the world (#1 is water). About 10 billion tons of concrete are produced every year and the most commonly used cement is Portland Cement, and concrete is rated by the amount of clinker contained within the cement, with the highest rating (for the strongest cement) at 95% clinker and 5% additives. Lower ratings contain less clinker.

Modified from: How concrete is made

Clinker can be replaced, either fully or partially, with certain types of rock dust and industrial by-products. There has been resistance from the construction sector due to safety concerns (not technically proven to be as strong) and pricing (high cost to switch equipment and materials).

Regulations

Regulations based on Portland cement clinker properties are preventing the widespread growth of lower-emission alternatives.

• Tests used to determine concrete strength are not always appropriate for alternative clinkers and cement. Concrete is tested for strength at 28 days but alternatives can take longer to develop the same strength and durability characteristics. (According to concrete expert)
• Europe
  • There are regulations on the type of cement that must be used based on the environment it will be used in (temperature, water exposure, etc) and the type of structure.
    • Eurocode 2 specifies the technical requirements of concrete structures in Europe.
• United States
  • In 2021, California became the 1st US state to pass a law requiring cement carbon emissions to be cut. The goal is to reduce emissions per ton by 40% below 2019 levels by 2035.
  • 5 firms control 43% of cement manufacturing and 5 of the 11 committee positions at the ASTM Cement Committee (develops cement standards) are held by reps from large cement corporations.
  • There are some concerns over the types of investments going to novel cement companies and that large tech and oil companies are putting themselves in a position to monopolize and regulators have been called on to step in and keep the industry competitive.

Reducing emissions