Global cement manufacturing is responsible for about 8% of the world's total CO2 emissions.^[1]  (Cement is the main ingredient in concrete, and cement is very rarely used on its own in construction, which means that for the purposes of the back-of-the-envelope calculation below, I will consider that cement and concrete are basically the same thing, even though strictly speaking cement is a sub component of concrete).

Despite alternatives existing, as of 2023, low-carbon cement materials accounted for approximately 3% of global total cement production (i.e. a negligible amount).^[2]

After a quick internet search, I found that green concrete reduces CO2 emissions by up to 30–80% compared to conventional concrete. It does so by replacing carbon-intensive Portland cement with industrial waste products like fly ash, slag, or silica fume.^[3]  The range is large because it depends on how many things you do to reduce emissions from a list of all possible interventions.

From these numbers it looks like making green concrete the norm in construction worldwide would mean cutting out anything between 2.4-7.4% of worldwide CO2 emissions. That's not nothing!

Not only is green concrete much environmentally friendlier, it's also similar in strength / in many cases even stronger than conventional concrete.^[4]

Why is green concrete not the norm already? 

It seems like the world is moving in that direction anyway, but things that are slowing down adoption are:

• In developed countries, it's the availability of waste materials. Many of the materials we need for green concrete such as fly ash and blast furnace slag, are by-products of coal-fired power plants and steel production. As these industries shut down, the supply of these materials is decreasing. That said, there still are many active coal-fired plants in North America and Europe, and even more in much of the developing world, e.g India and South East Asia, and regional 'pockets' in all seven continents).^[5] 

• In much of the developing world where it could be more easily widely adopted, progress is slowed down due to general inertia / lack of incentive for the industry to adapt and change its methods, and market and regulatory unreadiness (workers are not trained to use it, or the country lacks appropriate building regulations, standard technologies to make it, and clear information and labelling standards). See this report about Nigeria for example. 
  
  In many countries, favourable policies and incentives, in the form of finance instruments, already exist (see this about India and this about Nigeria) but somehow they have not been sufficient to drive a massive change of practice in the industry. 

Curious as to how 'attractive' this problem is to the EA community...
 

1. ^{^}

    World Economic Forum. https://www.weforum.org/stories/2024/09/cement-production-sustainable-concrete-co2-emissions/#:~:text=Global%20cement%20manufacturing%20is%20responsible,Image:%20Statista

2. ^{^}

   https://cleantech.com/record-371-9m-raised-for-low-carbon-cement-in-2024-but-20b-needed-by-2030/#:~:text=It's%20no%20coincidence%20that%20metropolitan,to%20the%20International%20Energy%20Agency.

3. ^{^}

   https://www.lapssethorizon.com/green-cement-for-concrete/#:~:text=It%20is%20also%20important%20to,carbon%20footprint%20of%20green%20concrete.
   
   Some companies even claim their concrete is carbon negative https://partanna.com/news-hub/what-is-carbon-negative-concrete
   
   https://www.bbc.co.uk/news/business-56716859#:~:text=That%20means%20it%20accounts%20for,EPFL

    

    

^{^}

https://carbonherald.com/how-is-green-cement-better-than-regular-cement/
 

^{^}

https://globalenergymonitor.org/projects/global-coal-plant-tracker/tracker/
https://www.elliottwood.co.uk/latest/green-cement-the-uncomfortable-truth
https://www.carbonbrief.org/mapped-worlds-coal-power-plants/

^{^}

Thinking of what LEEP did with supporting governments to adopt regulations banning the use of lead in paint.

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