[Gifted article link, good for 7 days] My modification to the title. This is an essential long read about concrete and it's most important ingredient, Portland cement. Concrete is the key building...
[Gifted article link, good for 7 days]
My modification to the title. This is an essential long read about concrete and it's most important ingredient, Portland cement.
Concrete is the key building material for modernity. Concrete's history, manufacture, carbon costs, economic impacts, engineering, distribution, and ever-growing uses have been significant contributors to climate-changing emissions.
Future developments in reengineering concrete's material composition, recycling, carbon capture during recycling, and other measures will be key to climate mitigation.
I'm absolutely agreed; this is super important! That said -- and I apologize for doing so -- I skimmed the sections which attempted to weave an emotional story about the damage that climate change...
I'm absolutely agreed; this is super important! That said -- and I apologize for doing so -- I skimmed the sections which attempted to weave an emotional story about the damage that climate change wrecks upon the world's least fortunate, and focused directly on the science.
Here're my thoughts on the article!
Almost every building erected in the past 75 years in an industrialized country has, at the least, a concrete foundation and, very likely, concrete floors.
There are robust, well tested alternatives! We've had permanent wood foundations (PWFs) since the 70s (example new construction a building science/marketing channel), and there are several approaches to avoiding putting in concrete floors (crawlspaces are an obvious one, which also have the benefit of making building utility repairs dramatically easier!). We even know how to build multi-storey buildings with only concrete in their foundations (example for up to six in Vancouver); one can imagine subbing in PWFs for those situations would be feasible, if potentially nerve wracking for the structural engineer of record.
[wind turbines, concrete in manufacturing plants, pipes, etc.]
The overarching fact about concrete is that it’s unavoidable. And the more it’s used, the more its use expands. Concrete is the material that networks almost every other built network.
Disagreed! I think that we've lacked the financial incentive to think outside the box in many fields, but that alternatives are clearly possible. In many cases, I'd imagine that fibreglass-reinforced plastics could take the place of concrete directly (e.g. wind turbines do this already), and in others, a thin concrete liner could provide chemical and wear resistance to an otherwise primarily plastic pipe (e.g. water transport). Manufacturing plants also needn't use concrete -- we did just fine with wood block floors for ages until concrete (as the article notes) became cost effective enough to replace it. Even dams can have their concrete usage dropped dramatically (for context, concrete is only necessary on the face of that retention structure; the rest of it is just plastic webbing and whatnot)
There are always going to be situations where concrete is absolutely necessary, but I would hazard that it's dramatically fewer than the places we use it today.
Bermejo pointed out that carbon emissions don’t come only from construction materials. For most buildings the majority of emissions result from running the facility — heating it, cooling it, lighting it — over time. The built environment accounts for about 40% of global carbon emissions, with 13% generated by erecting and repairing structures and the rest from their ongoing use.
Ooh, yeah, the journalist should've caught that. They're comparing operational vs. embodied carbon, and that person is using a very motivated definition of "most" buildings. If folks are interested I can try to track down some old stats I was seeing, but afaik -- under modern building codes (for residential construction, at least), improvements to factors affecting operational efficiency (i.e. insulating, making improved windows, air sealing, modernizing HVAC, etc.) have effectively moved the target to embodied carbon, not away. I'd imagine that the executive who runs a company which produces the material responsible for ~36% ([1]) of a typical residential building's embodied carbon would have some motivation for getting ahead of criticism 😅
Here's your vital equation for concrete and climate: CaCO3 + heat = CaO + CO2 or Calcite* + heat = Lime** + carbon dioxide *calcite is the principal mineral in most limestone **lime is the main...
Here's your vital equation for concrete and climate:
CaCO3 + heat = CaO + CO2
or
Calcite* + heat = Lime** + carbon dioxide
*calcite is the principal mineral in most limestone
**lime is the main ingredient in cement
Every kg of lime generates ~0.8 kg of carbon dioxide, before considering how temps of 2700°F are maintained. I'd read some studies of labs doing the process using far less energy using electrochemistry, though I don't recall the details, but it certainly wasn't at scale.
Blue Planet has an interesting approach, curious if that gains traction, but doesn't really help the concrete situation. Sure, it can substitute aggregate that hasn't captured atmospheric carbon, but doesn't change the above equation or method of making concrete.
I'm having a hard time buying these energy storage claims work out practically, but I don't imagine MIT attempts to commercialize ideas to be proven wrong.
It's a hard problem of climate change, if not one of the hardest, and doesn't get discussed too often. This article goes over a lot of the work going into it. Thanks for posting!
[Gifted article link, good for 7 days]
My modification to the title. This is an essential long read about concrete and it's most important ingredient, Portland cement.
Concrete is the key building material for modernity. Concrete's history, manufacture, carbon costs, economic impacts, engineering, distribution, and ever-growing uses have been significant contributors to climate-changing emissions.
Future developments in reengineering concrete's material composition, recycling, carbon capture during recycling, and other measures will be key to climate mitigation.
I'm absolutely agreed; this is super important! That said -- and I apologize for doing so -- I skimmed the sections which attempted to weave an emotional story about the damage that climate change wrecks upon the world's least fortunate, and focused directly on the science.
Here're my thoughts on the article!
There are robust, well tested alternatives! We've had permanent wood foundations (PWFs) since the 70s (example new construction a building science/marketing channel), and there are several approaches to avoiding putting in concrete floors (crawlspaces are an obvious one, which also have the benefit of making building utility repairs dramatically easier!). We even know how to build multi-storey buildings with only concrete in their foundations (example for up to six in Vancouver); one can imagine subbing in PWFs for those situations would be feasible, if potentially nerve wracking for the structural engineer of record.
Disagreed! I think that we've lacked the financial incentive to think outside the box in many fields, but that alternatives are clearly possible. In many cases, I'd imagine that fibreglass-reinforced plastics could take the place of concrete directly (e.g. wind turbines do this already), and in others, a thin concrete liner could provide chemical and wear resistance to an otherwise primarily plastic pipe (e.g. water transport). Manufacturing plants also needn't use concrete -- we did just fine with wood block floors for ages until concrete (as the article notes) became cost effective enough to replace it. Even dams can have their concrete usage dropped dramatically (for context, concrete is only necessary on the face of that retention structure; the rest of it is just plastic webbing and whatnot)
There are always going to be situations where concrete is absolutely necessary, but I would hazard that it's dramatically fewer than the places we use it today.
Ooh, yeah, the journalist should've caught that. They're comparing operational vs. embodied carbon, and that person is using a very motivated definition of "most" buildings. If folks are interested I can try to track down some old stats I was seeing, but afaik -- under modern building codes (for residential construction, at least), improvements to factors affecting operational efficiency (i.e. insulating, making improved windows, air sealing, modernizing HVAC, etc.) have effectively moved the target to embodied carbon, not away. I'd imagine that the executive who runs a company which produces the material responsible for ~36% ([1]) of a typical residential building's embodied carbon would have some motivation for getting ahead of criticism 😅
I, uh, no comment.
[1]: "Concrete is the leading contributor to emissions from the sample houses,
representing over 36 percent of all material emissions" Materials emissions benchmark report for part 9 homes in Vancouver, pg. 22
Here's your vital equation for concrete and climate:
CaCO3 + heat = CaO + CO2
or
Calcite* + heat = Lime** + carbon dioxide
*calcite is the principal mineral in most limestone
**lime is the main ingredient in cement
Every kg of lime generates ~0.8 kg of carbon dioxide, before considering how temps of 2700°F are maintained. I'd read some studies of labs doing the process using far less energy using electrochemistry, though I don't recall the details, but it certainly wasn't at scale.
Blue Planet has an interesting approach, curious if that gains traction, but doesn't really help the concrete situation. Sure, it can substitute aggregate that hasn't captured atmospheric carbon, but doesn't change the above equation or method of making concrete.
I'm having a hard time buying these energy storage claims work out practically, but I don't imagine MIT attempts to commercialize ideas to be proven wrong.
It's a hard problem of climate change, if not one of the hardest, and doesn't get discussed too often. This article goes over a lot of the work going into it. Thanks for posting!