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Comment by Gravityloss | Hacker News Reader

If carbon emissions become really expensive, other materials than concrete become more viable.

Steel can be quite carbon intensive as well though.

Timber and mud could become great again. Also hydro cut stone.

What are you referring to when you mention hydro cut stone? A quick google shows gemstone cutting, small subtractive milling of gargoyles and cutting/etching of thin decorative stone.

Are you talking about a quarrying process? I've got a little bit of knowledge about quarrying as there are many active limestone quarries in my area, but always interested to learn more.

My guess would be water-jet cut stone blocks. At the quarry you often cut stuff off in big slabs; once you’ve got the slabs at the water-jet, you could cut standard dimension blocks out of the slab and have a pretty modular building material.

Yeah that's what I meant. Why would one prefer concrete over that?

Imagine the scale of the gaping maw left behind after a century of quarrying for high quality stone to support modern city construction.

Concrete materials come from somewhere as well. But yes, if the material would cost more, it would be used more sparingly.

Maybe I come from a country that has plenty of solid rock to go around.

While not my field at all, I would imagine that given the relatively generic character of the source material required for concrete it might be easier to find suitable locations for extraction. Although I seem to recall reading about potential shortages for certain types of sand, so maybe I'm wrong about that.

Generally speaking, whenever specific qualities of a raw material become linked to its intended use, the market becomes more willing to accept negative externalities in its procurement.

Engineered timber is surprisingly strong and fire resistant - the problem is in what the word "engineered" means in terms of environmental impact.

Timber is about as pure stored CO₂ as you can get.

It's the impermanence of standard stick construction that ruins the gains of switching materials. Cross laminated timber seems to have potential, however it is significantly more expensive for the moment.

The formaldehyde-based adhesives that are used in engineered timbers also complicated the picture a bit, from long-term health and sustainability perspectives.

Perfect world would be a much larger supply of old-growth hardwoods with characteristics that make them ideal for construction. If some synthetic means of growing such material comes around, that could be a game changer.

My understanding is that polyurethane adhesives are better suited for CLT, and don't have the same emissions problems.

Your point is well taken though: the entire supply chain needs to be accounted for, in addition to the lifetime of the structures.

There are also ways around this. You can join softwood with screws made out of hardwood. There's a German company making those. Some companies join boards with aluminum nails. You can make massive wood from cheap material without glue. There's a company that makes boards with a wavy surface. Multiple boards lock together easily. They made a prototype bridge with very little fastening.

Steel is the easiest to recycle and reuse though.

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