Rant: The Mediocrity of Our Construction Materials

[seicer]

You are referring to Corten steel. It does not hold up well in salty environments. If you ever travel north and check out what remains of Corten steel guardrails in New York State, or in areas where deicing agents are used, you'll see a pattern of extensive corrosion. I made a note here on AARoads some years ago where I had noted a lot of Corten guardrail along the highways in the Adirondacks had rusted away.

Then you have the Corten steel gantries (sign supports) in Charleston, West Virginia that have been mostly replaced with conventional galvanized gantries. Vibrations from traffic and salt spray caused extensive deterioration to the structures.

In general, rebar needs to be clean for it to be encased in concrete. It shouldn't be rusting (either as steel or as Corten which can take months to cure).

[Sani]

2.  Regarding steel (and in particular rebar and rebar mesh as used in concrete structures) I have in recent years seen something that would seem to increase the lifespan of rebar at fairly low cost - applying a coat of rubber or maybe rubberized latex compound to coat the steel and make it less vulnerable to corrosion.   Seems like a fairly low-cost way to extend the life of the rebar (and thus the concrete structures where it is used).

Epoxy-coated rebar actually has some vulnerabilities that can make it a poor choice, because any tear or puncture in the coating not only allows moisture into the rebar, it also traps that moisture against it, leading to very quick failure. It's been banned in Quebec, and several other provinces and states recommend against its use in environments where exposure to chlorides is expected.

[kphoger]

Concrete is made of stuff like busted-up rocks, gypsum, and calcium oxide:  really common stuff.  Some new technology that hasn't been invented in the last–oh, you know, 2500 years–is bound to be more expensive by virtue of its using less commonly available materials.

[kalvado]

Concrete is made of stuff like busted-up rocks, gypsum, and calcium oxide:  really common stuff.  Some new technology that hasn't been invented in the last–oh, you know, 2500 years–is bound to be more expensive by virtue of its using less commonly available materials.

Yes, but there may be some options even with cheap source materials
I am thinking single crystal aluminum oxide (ruby, sapphire) and amorphous - or again single crystal - quartz. These require high tech processing with lots of energy. But I can see them being the next-next-gen materials at some point.
Ruby rebar, fused silica fiber in good old cement... Nothing to corrode!

[seicer]

Well, for concrete you need specific grades of sand that's not as readability available. Conflicts have arisen over its scarcity: https://99percentinvisible.org/episode/built-on-sand/

[SectorZ]

I mean, if this didn't have the rant about urbanists, it might have been a half-decent thread.

But construction materials don't have to "suck" if they are properly maintained. The corrosion that you saw in the condos was the direct result of bad design and engineering that led to water intrusion over the course of decades into the structural elements of the tower. For bridges, corrosion is the byproduct of the misapplication or overapplication of salt and the ill-maintenance of the structures to withstand the intrusion (i.e. being diligent in sealing the cracks and painting the surface). For highways, it's often because of value engineering the construction to the point that pavements only last 20 years without needing major rehabilitation. Or worse, needing rehabilitation off-the-bat (i.e. US 35 in West Virginia, King Coal Highway near Williamson).

But a good material should be idiotproof

Mother nature shows us a better material and humanity will engineer a bigger idiot in response. Always has, always will.

[SEWIGuy]

I mean, if this didn't have the rant about urbanists, it might have been a half-decent thread.

But construction materials don't have to "suck" if they are properly maintained. The corrosion that you saw in the condos was the direct result of bad design and engineering that led to water intrusion over the course of decades into the structural elements of the tower. For bridges, corrosion is the byproduct of the misapplication or overapplication of salt and the ill-maintenance of the structures to withstand the intrusion (i.e. being diligent in sealing the cracks and painting the surface). For highways, it's often because of value engineering the construction to the point that pavements only last 20 years without needing major rehabilitation. Or worse, needing rehabilitation off-the-bat (i.e. US 35 in West Virginia, King Coal Highway near Williamson).

But a good material should be idiotproof

This statement makes no sense.

[Georgia]

an idiot proof material has never met a concrete mixing/asphalt plant i am afraid to say