Concrete. Second only to water in how much we use.
Front
Concrete
Second only to water in how much we use
The material most of the built world is made from, and its real cost.
Back
Humans use more concrete than any substance except water. Making cement means heating limestone until it gives up carbon dioxide, so the chemistry itself releases the gas before a drop of fuel is burnt. Cement is responsible for something like 7% of world emissions. India is the second largest producer, because India is still being built.
- Concrete is strong under compression and weak under tension, so steel bars are cast inside it. The two happen to expand at nearly the same rate when heated.
- Reinforced concrete has a lifespan. Once water reaches the steel and it rusts, it swells and cracks the concrete from within. Nothing built this way is permanent.
IEA cement technology roadmap
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