[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 😅
There are some serious limits on the substitutability of wood for concrete, though. You can build six-story timber frames, but not dense urban skyscrapers, roads, or massive dams, bridges, and...
There are some serious limits on the substitutability of wood for concrete, though. You can build six-story timber frames, but not dense urban skyscrapers, roads, or massive dams, bridges, and subterranean infrastructure. I've seen those solid wood factory floors, and the modern cost would be astronomical given how few large-diameter hardwood trees are left. Fire-retardant technology has gotten better, there's research on silicated wood treatments that might resist wet conditions more effectively, but wood still won't make up more than a fraction of concrete applications.
I'm not saying we can't substitute a fair amount of concrete, though. For housing, adobe, rammed earth, modular panels, bamboo, and other solutions can still support fair density and lower environmental impact. Provided that they're chosen appropriately for local availability and conditions.
The article also mentions the risks from clear-cutting trees - damaging CO2 and methane emissions from exposed decaying forest floor materials.
Oh absolutely! To put my point more precisely: the most carbon efficient yard of concrete is the one we didn't use, so putting effort into reducing utilization is often a huge bang for the buck....
There are some serious limits on the substitutability of wood for concrete, though.
Oh absolutely! To put my point more precisely: the most carbon efficient yard of concrete is the one we didn't use, so putting effort into reducing utilization is often a huge bang for the buck. In effectively every sense I do not see things as binaries, so I'm not proposing that the world can go "concrete-free" at the drop of the hat -- only that there's likely a lot of low hanging fruit by thinking about alternatives in end-uses, as opposed to pursuing diminishing returns surrounding CO2e reduction in concrete production.
I won't go point by point, since I don't think we're having like a debate or anything, but wood's good to 18 stories with mass timber (the structural system is mostly timber, but there's definitely concrete and steel in there playing supporting roles), and the floors mentioned don't use large diameter wood anyhow -- it's often 4x4's or 6x6's, and there's no compelling reason to keep 'em wood (they're still making them out of SYP, which is very much not old growth in 2026). Anything cellulostic with roughly the same material properties (i.e. endgrain is tough, can be sealed with oil) should behave similarly, too. Some industrial wood block flooring companies already do so with (seemingly) wood-plastic composites!
I've seen those solid wood factory floors [...]
That's really cool! I think they're all out east, effectively, and I've never had a chance to see one in person. There're a few public spaces which have 'em and they've held up great, though!
[...] but wood still won't make up more than a fraction of concrete applications.
Yeah I think that's where I would love to have more info? I threw a very cursory look into this, and turned up this dubious report. Taking their numbers with a grain of salt, it sounds like ~43% of cement usage is in roads/bridges, ~28% are residential, and 19% is "non-residential demand" (presumably, commercial/industrial, but the article frames it as "AI datacentres"). Even if we pretend that the 43% is untouchable (dubious IMO but perhaps there's a civil engineer around who could dig in further), that leaves another ~47% which could be meaningfully addressed by reducing concrete usage. For instance, it seems like AI datacentres are mostly one storey (just based on vibes, since searching it always turns up images like this one), which could easily be built without any concrete: gravity loads seem low enough to be handled with some of the plywood-on-grade flooring options, and if it's one storey, wood framing it (maybe with trusses to get decent enough clear spans for racks) seems very plausible.
I'm not saying we can't substitute a fair amount of concrete, though.
🤦 apologies, I appear to have skipped this sentence before writing the above response. I suppose it still applies, but please consider it moreso a soft push instead of the hard counterpoint I had originally penned.
The article also mentions the risks from clear-cutting trees - damaging CO2 and methane emissions from exposed decaying forest floor materials.
Oh totally fair. But no solution is perfect, so we need to compare them against each other instead of studying each in a vacuum. Perfect should not be the enemy of the good, and etc. Sustainable forestry management is possible, and since we haven't done tonnes of applied research into it yet, I expect that the CO2 emissions reductions possible are still firmly in the 20% effort/80% return zone.
edit: I got a little nerd sniped XD I'd not looked into bridges much, so a bunch of this is new to me, but apparently FRP bridges are a thing! They seem primarily used for pedestrians, however. Covered wooden bridges have a surprisingly long service life (up to 100 years, with maintenance!), and we have extensive experience with wooden trestle bridges for rail traffic. It looks like there's some research into FRP as an alternative to steel for buried bridges (apparently, AKA "soil-steel composite bridge", or "steel culvert bridges) which can themselves be scaled up very impressively.
Super cool, and I appreciate the links! As you said, not trying to argue at all. I'll admit that I was taken aback by the sheer scale of concrete usage described in the article. It was hard to...
Super cool, and I appreciate the links! As you said, not trying to argue at all.
I'll admit that I was taken aback by the sheer scale of concrete usage described in the article. It was hard to imagine substituting an effective fraction of an industry that uses 4.5 billion tons of limestone annually for the Portland cement component. I can remember when "pave the Earth" was a big joke... 14 billion cubic meters of concrete poured per year feels unstoppable in the same way that fossil fuel use felt unstoppable until economies of scale worked for manufacturing the alternatives.
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
There are some serious limits on the substitutability of wood for concrete, though. You can build six-story timber frames, but not dense urban skyscrapers, roads, or massive dams, bridges, and subterranean infrastructure. I've seen those solid wood factory floors, and the modern cost would be astronomical given how few large-diameter hardwood trees are left. Fire-retardant technology has gotten better, there's research on silicated wood treatments that might resist wet conditions more effectively, but wood still won't make up more than a fraction of concrete applications.
I'm not saying we can't substitute a fair amount of concrete, though. For housing, adobe, rammed earth, modular panels, bamboo, and other solutions can still support fair density and lower environmental impact. Provided that they're chosen appropriately for local availability and conditions.
The article also mentions the risks from clear-cutting trees - damaging CO2 and methane emissions from exposed decaying forest floor materials.
Oh absolutely! To put my point more precisely: the most carbon efficient yard of concrete is the one we didn't use, so putting effort into reducing utilization is often a huge bang for the buck. In effectively every sense I do not see things as binaries, so I'm not proposing that the world can go "concrete-free" at the drop of the hat -- only that there's likely a lot of low hanging fruit by thinking about alternatives in end-uses, as opposed to pursuing diminishing returns surrounding CO2e reduction in concrete production.
I won't go point by point, since I don't think we're having like a debate or anything, but wood's good to 18 stories with mass timber (the structural system is mostly timber, but there's definitely concrete and steel in there playing supporting roles), and the floors mentioned don't use large diameter wood anyhow -- it's often 4x4's or 6x6's, and there's no compelling reason to keep 'em wood (they're still making them out of SYP, which is very much not old growth in 2026). Anything cellulostic with roughly the same material properties (i.e. endgrain is tough, can be sealed with oil) should behave similarly, too. Some industrial wood block flooring companies already do so with (seemingly) wood-plastic composites!
That's really cool! I think they're all out east, effectively, and I've never had a chance to see one in person. There're a few public spaces which have 'em and they've held up great, though!
Yeah I think that's where I would love to have more info? I threw a very cursory look into this, and turned up this dubious report. Taking their numbers with a grain of salt, it sounds like ~43% of cement usage is in roads/bridges, ~28% are residential, and 19% is "non-residential demand" (presumably, commercial/industrial, but the article frames it as "AI datacentres"). Even if we pretend that the 43% is untouchable (dubious IMO but perhaps there's a civil engineer around who could dig in further), that leaves another ~47% which could be meaningfully addressed by reducing concrete usage. For instance, it seems like AI datacentres are mostly one storey (just based on vibes, since searching it always turns up images like this one), which could easily be built without any concrete: gravity loads seem low enough to be handled with some of the plywood-on-grade flooring options, and if it's one storey, wood framing it (maybe with trusses to get decent enough clear spans for racks) seems very plausible.
🤦 apologies, I appear to have skipped this sentence before writing the above response. I suppose it still applies, but please consider it moreso a soft push instead of the hard counterpoint I had originally penned.
Oh totally fair. But no solution is perfect, so we need to compare them against each other instead of studying each in a vacuum. Perfect should not be the enemy of the good, and etc. Sustainable forestry management is possible, and since we haven't done tonnes of applied research into it yet, I expect that the CO2 emissions reductions possible are still firmly in the 20% effort/80% return zone.
edit: I got a little nerd sniped XD I'd not looked into bridges much, so a bunch of this is new to me, but apparently FRP bridges are a thing! They seem primarily used for pedestrians, however. Covered wooden bridges have a surprisingly long service life (up to 100 years, with maintenance!), and we have extensive experience with wooden trestle bridges for rail traffic. It looks like there's some research into FRP as an alternative to steel for buried bridges (apparently, AKA "soil-steel composite bridge", or "steel culvert bridges) which can themselves be scaled up very impressively.
Super cool, and I appreciate the links! As you said, not trying to argue at all.
I'll admit that I was taken aback by the sheer scale of concrete usage described in the article. It was hard to imagine substituting an effective fraction of an industry that uses 4.5 billion tons of limestone annually for the Portland cement component. I can remember when "pave the Earth" was a big joke... 14 billion cubic meters of concrete poured per year feels unstoppable in the same way that fossil fuel use felt unstoppable until economies of scale worked for manufacturing the alternatives.
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!
Side comment: that's an awful lot of tags! Are you autogenerating them somehow?
Nope, purely handcrafted tags. I suppose I'd post more often if I wasn't so obsessive about keyword labeling.