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Do we need to stop building with concrete?

Posted: Sun Sep 29, 2019 8:08 pm
by FangKC
We may have to abandon concrete to fight climate change, architectural experts say
A group of experts at the Architecture of Emergency climate summit in London have identified an unlikely source of greenhouse gas emissions: concrete.

"If we invented concrete today, nobody would think it was a good idea," said architectural engineer and panel member Michael Ramage. "We've got this liquid and you need special trucks, and it takes two weeks to get hard. And it doesn't even work if you don't put steel in it."
...
https://bigthink.com/technology-innovat ... belltitem1

Q&A: Why cement emissions matter for climate change

https://www.carbonbrief.org/qa-why-ceme ... ate-change

Re: Do we need to stop building with concrete?

Posted: Mon Sep 30, 2019 8:36 am
by flyingember
This is like the coffee mug vs disposable paper cup argument. If you're just looking at two variables it's going to be over simplified.

Is concrete really greener than wood framing? Concrete structures can crumble but if we replace the concrete fountain with wood we're going to see a dramatic increase in the need for wood to repair foundtaions from wood rot. If we kill dramatically more trees will be reduce greenhouse gas turnover greater than the amount we produce from concrete?

What's the ongoing cost difference of insulating a wooden floor vs a concrete floor on the utility system? Is it more green to construct more power systems, transport more insulation to homes and the like than the insulation concrete provides?

Re: Do we need to stop building with concrete?

Posted: Mon Sep 30, 2019 10:10 am
by normalthings
flyingember wrote:
Mon Sep 30, 2019 8:36 am
This is like the coffee mug vs disposable paper cup argument. If you're just looking at two variables it's going to be over simplified.

Is concrete really greener than wood framing? Concrete structures can crumble but if we replace the concrete fountain with wood we're going to see a dramatic increase in the need for wood to repair foundtaions from wood rot. If we kill dramatically more trees will be reduce greenhouse gas turnover greater than the amount we produce from concrete?

What's the ongoing cost difference of insulating a wooden floor vs a concrete floor on the utility system? Is it more green to construct more power systems, transport more insulation to homes and the like than the insulation concrete provides?
Cross Laminated Timber is the future of above ground structural materials. It is: carbon negative, as strong as steel/concrete, cheaper, lighter, faster to produce, faster to put into a construction, more fire resistant. Concrete will be used for foundations for the foreseeable future

Most wood harvesting in North America is done in a sustainable manner. Infact, we have more trees now than we did in the 40’s and continue to grow more.

Re: Do we need to stop building with concrete?

Posted: Mon Sep 30, 2019 12:51 pm
by Eon Blue
Don't forget about all the concrete we drive on.

Re: Do we need to stop building with concrete?

Posted: Mon Sep 30, 2019 1:40 pm
by WSPanic
Jeez.... we saw what happened when we came for the plastic straws. Can only imagine the backlash with this.

Re: Do we need to stop building with concrete?

Posted: Mon Sep 30, 2019 3:18 pm
by town cow
Just don't tell Jonathan Arnold.

Re: Do we need to stop building with concrete?

Posted: Mon Oct 14, 2019 6:31 am
by chaglang
I haven’t done a lot of research on this, but offhand I can’t think of how you would build the foundation of a building without concrete.

Re: Do we need to stop building with concrete?

Posted: Mon Oct 14, 2019 9:54 am
by flyingember
chaglang wrote:
Mon Oct 14, 2019 6:31 am
I haven’t done a lot of research on this, but offhand I can’t think of how you would build the foundation of a building without concrete.
Instead of a four inch basement slab on grade put in a waterproof membrane, cover it with a hard clay, cover with another membrane let it dry out and lay vinyl tiles on top. For 1000 square feet that's a truck worth of concrete not used. A lot of homes could make use of this method. It would be especially nice for garages or barns.


We also want to think about repairability

There's a lot of poured concrete foundations that are super thin but if they crumble are really expensive to fix. Concrete blocks aren't much greener up front but if you lose a few blocks you support the home, knock them out and replace them. Blocks can also be delivered with other supplies minimizing the number of truck deliveries, greening up the build that way.


We should look into methods like post on beam which use only footings.
This is a bit old but this shows how in some environments how simple a footing we can use for a home.
https://unofficialculture.wordpress.com ... al-method/


Basements are a safety feature in the midwest but imagine if instead of a full basement we built safety rooms . Here's an interesting design which replaces extensive use of concrete with a design that takes advantage of an extreme slope.
https://logangate.com/the-amity/

Re: Do we need to stop building with concrete?

Posted: Mon Oct 14, 2019 12:53 pm
by chaglang
SFH construction isn't my forte, but I'd be very nervous about relying on a subgrade membranes to keep clay dry. There isn't much margin for error: if a hole ever develops in the membrane and the clay gets wet, look out. Also, the manufacturing process for vinyl is pretty horrible environmentally.

The OP was meant to be more about commercial buildings. I've been thinking about this a bit this morning and I can't think of how you'd build the foundation of a, say, 5 story commercial building without concrete.

Re: Do we need to stop building with concrete?

Posted: Mon Oct 14, 2019 12:53 pm
by Eon Blue
chaglang wrote:
Mon Oct 14, 2019 6:31 am
I haven’t done a lot of research on this, but offhand I can’t think of how you would build the foundation of a building without concrete.
What about a natural substance with properties similar to concrete that could be extracted from the ground, cut to size, and stacked? :lol:

The pragmatic answer is that we could still use concrete in moderation, for the select applications where it is best suited. Use steel and timber for vertical construction. Use stone or brick pavers for flat work.

Re: Do we need to stop building with concrete?

Posted: Mon Oct 14, 2019 1:03 pm
by chaglang
Eon Blue wrote:
Mon Oct 14, 2019 12:53 pm
chaglang wrote:
Mon Oct 14, 2019 6:31 am
I haven’t done a lot of research on this, but offhand I can’t think of how you would build the foundation of a building without concrete.
What about a natural substance with properties similar to concrete that could be extracted from the ground, cut to size, and stacked? :lol:
Ice?

Re: Do we need to stop building with concrete?

Posted: Mon Oct 14, 2019 1:22 pm
by flyingember
chaglang wrote:
Mon Oct 14, 2019 12:53 pm
The OP was meant to be more about commercial buildings. I've been thinking about this a bit this morning and I can't think of how you'd build the foundation of a, say, 5 story commercial building without concrete.
Something like this?

https://evstudio.com/steel-screw-pile-foundation/

Re: Do we need to stop building with concrete?

Posted: Mon Oct 14, 2019 1:42 pm
by chaglang
You could also do a rammed aggregate pile. But I think you still need concrete to transfer the building loads down to the piles.

Caveat: architect talking about structural engineering.

Re: Do we need to stop building with concrete?

Posted: Mon Oct 14, 2019 10:49 pm
by FangKC
I think the conversation should be how can structures be built without using so much concrete.

In the South, you see homes that are built on footings and the house is raised above the ground. Venice is built on wooden piers that were pounded into the ground under the harbor. There are multi-story commercial buildings that sit on large blocks of stone mortared together. Many KC houses are built on stone and mortar foundations.

China used more cement from 2011-13 than the USA used in the entire 20th Century. Production of cement and concrete produces a significant amount of carbon gases.

https://www.forbes.com/sites/niallmccar ... 7b5dcf4131

If the undeveloped world uses concrete at the same rate as China, it's unsustainable. If we build concrete buildings, and tear them down every 40-60 years, it's unsustainable.

Re: Do we need to stop building with concrete?

Posted: Tue Oct 15, 2019 5:22 am
by FangKC
Built by robots: This Swiss company could change the construction industry forever
...
The three-level building near Zurich features 3D-printed ceilings, energy-efficient walls, timber beams assembled by robots on site, and an intelligent home system. Developed by a team of experts at ETH Zurich university and 30 industry partners over the course of four years, the DFAB House, measuring 2,370 square feet (220 square meters), needed 60% less cement and has passed the stringent Swiss building safety codes.
...
https://www.weforum.org/agenda/2019/10/ ... n-industry

Re: Do we need to stop building with concrete?

Posted: Tue Oct 15, 2019 7:33 am
by shinatoo
In addition to the carbon footprint of concrete, we are actually going to run out of sand at some point.

Desert and beach sand cannot be used as an aggregate as it is too smooth. Must be river sand.

Big lawsuit against a proposed sand mine in Kansas right now.

https://www.forbes.com/sites/lauriewink ... 76849b1240

https://www.apnews.com/44605103a9f9472ba4515c410b65f8e0

Re: Do we need to stop building with concrete?

Posted: Tue Oct 15, 2019 8:26 am
by chaglang
So all of these things have tradeoffs. 60% less concrete is great, but what kind of resins are in the 3d printing process? (And, as an aside, if you're designing a house that requires a series of 30' concrete cantilevers, perhaps your architectural education should come in for some criticism.) What binders were used in the glulams? Where'd the timber come from? I saw an article that the spark suppression gas in electrical switchgear is like 50x worse for the atmosphere than CO2. Even switching from something like vinyl tile to rubber tile isn't the easy moral choice you'd expect because the rubber tile has vinyl in it also. Photovoltaics are full of toxic chemicals and not easy to recycle.

For all the sexiness of 3D printing, as long as Swiss university students building a house using 3D printed structure is news, that should also tell you it's a technology that's unavailable to 98% of the world. And I wonder if the real tradeoff of 3d printing single family homes is inducing poor land use and shifting the carbon footprint from your house to your car.

Not to be all Debbie Downer... but I'm pessimistic that the small improvements that you can make the building process - especially outside of the SFH segment - add up to anything significant. Which isn't to say not to try, just that the impact is frustratingly limited.

Re: Do we need to stop building with concrete?

Posted: Tue Oct 15, 2019 8:37 am
by Riverite
What about building denser developments without parking garages. That should decrease the concrete use and the issue of co2 dispersion from driving. Would it be possible to use less concrete due to lessening the weight requirements

Re: Do we need to stop building with concrete?

Posted: Wed Oct 16, 2019 10:39 pm
by FangKC
You can create really dense urban environments building with wood that are pedestrian-friendly, and augment them with public transit. People just have to be willing to live differently.

Re: Do we need to stop building with concrete?

Posted: Fri Oct 25, 2019 7:25 pm
by FangKC
What is the Future of Concrete in Architecture?

https://www.archdaily.com/926854/what-i ... ource=swap