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The problem with reinforced concrete (2016)

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Re: The problem with reinforced concrete (2016)

#31

Post by raylad »

idoh wrote: post #18

I don't know if it is really a problem, more like a tradeoff. Reinforced concrete costs less and enables shapes that are impossible without it, with the downside that the buildings last 50 years instead of 100+ years. The present value of a building that lasts 50 years is not that much different that the same one that lasts 100 years. With that in mind, it makes perfect sense to make an office building out of reinfor…

It will become a very big problem if/when buildings start collapsing with people in them.

I grew up partly in an 18 story reinforced concrete building built in the 1920s. The apartment I lived in was recently sold for several million dollars.

Once, when there was a leak and the plaster came off, the underlying concrete was exposed and it scraped away like very weak sandstone.

How strong is the building and when will it collapse? Does anyone know? Is anyone testing?

I think the answer to both of those questions is "no". Everyone seems to assume they will stand forever. They won't.

Re: The problem with reinforced concrete (2016)

#32

Post by cle »

nerdponx wrote: post #20
idoh wrote: post #18

I don't know if it is really a problem, more like a tradeoff. Reinforced concrete costs less and enables shapes that are impossible without it, with the downside that the buildings last 50 years instead of 100+ years. The present value of a building that lasts 50 years is not that much different that the same one that lasts 100 years. With that in mind, it makes perfect sense to make an office building out of reinfor…

> The present value of a building that lasts 50 years is not that much different that the same one that lasts 100 years. That's a problem in and of itself, IMO. Construction is tremendously resource-intensive. We should not be building "throwaway" buildings.

Not so straightforward. Sometimes we throw things away to make room for better things.

Re: The problem with reinforced concrete (2016)

#34

Post by Taek »

minikites wrote: post #4
brutusborn wrote: post #3

This should be an economics piece, not an environmental piece. The author states that "one of iron’s unalterable properties is that it rusts" yet further on acknowledges the existence of stainless steel. There's nothing wrong with reinforced concrete, but the incentives to produce long lasting buildings are not there. The cheapest bidder will generally win and their building will last the "design life" of the buildin…

Is it a good thing for society to directly incentivize the construction of longer lasting buildings?

Maybe sufficient to require that construction put down enough money to cover deconstruction and cleanup when building.

Re: The problem with reinforced concrete (2016)

#35

Post by diegocg »

raylad wrote: post #31
idoh wrote: post #18

I don't know if it is really a problem, more like a tradeoff. Reinforced concrete costs less and enables shapes that are impossible without it, with the downside that the buildings last 50 years instead of 100+ years. The present value of a building that lasts 50 years is not that much different that the same one that lasts 100 years. With that in mind, it makes perfect sense to make an office building out of reinfor…

It will become a very big problem if/when buildings start collapsing with people in them. I grew up partly in an 18 story reinforced concrete building built in the 1920s. The apartment I lived in was recently sold for several million dollars. Once, when there was a leak and the plaster came off, the underlying concrete was exposed and it scraped away like very weak sandstone. How strong is the building and when will…

Unless you are living in a developing country, the answer to the second question should be "yes".

Re: The problem with reinforced concrete (2016)

#36

Post by foolmeonce »

idoh wrote: post #18

I don't know if it is really a problem, more like a tradeoff. Reinforced concrete costs less and enables shapes that are impossible without it, with the downside that the buildings last 50 years instead of 100+ years. The present value of a building that lasts 50 years is not that much different that the same one that lasts 100 years. With that in mind, it makes perfect sense to make an office building out of reinfor…

Having 1 in 25 buildings being completely rebuilt at all times and another 1 in ~5 getting renovations is extremely annoying.

I think buildings that are too regularly under construction should carry some tax penalties, instead renovating non-durable buildings to tastelessness is a way to save on property taxes, get tax deductions and try to pressure tenants out to get the latest upscale rates.

Re: The problem with reinforced concrete (2016)

#37

Post by 0xbadcafebee »

matheusmoreira wrote: post #22
ajcp wrote: post #21

Earlier quoted context omitted.

Yes.

Please elaborate. Which materials and methods?

There is no way to know other than to ask the architect. You can make educated guesses but that still won't tell you. Even then it's up to the contractors to have done everything properly.

Or if it's made of stone. Stacking giant stones on top of each other is a sure-fire way to make a building outlive you.

After that, the longest-lived buildings that I am aware of are made of wood. The catch is they've been rebuilt 50 times, once per time they burned to the ground.

After those, the longest-lived buildings are made of Roman concrete that we can't reproduce. (To give you an idea how insane Roman concrete was, you can go kayaking north of Naples, and kayak through a concrete Roman building that is sitting on piles in the Mediterranean sea)

Re: The problem with reinforced concrete (2016)

#38

Post by joshuaheard »

tonylemesmer wrote: post #19

Tangentially related. This company using graphene laced concrete to reduce the amount of cement required. And eliminating steel. New product called "Concretene". [0] https://twitter.com/Paul_Denney/status/1397132479144812544 [1] https://www.punchline-gloucester.com/articles/aanews/glouces...

The contractor I used on a remodel spoke of carbon fiber reinforced concrete, which I googled, and it's called "carboconcrete". It is described as, "a highly stressable lightweight composite construction that combines special fine grain ultra high-strength concrete and carbon fibers."

Re: The problem with reinforced concrete (2016)

#39

Post by idoh »

nerdponx wrote: post #20
idoh wrote: post #18

I don't know if it is really a problem, more like a tradeoff. Reinforced concrete costs less and enables shapes that are impossible without it, with the downside that the buildings last 50 years instead of 100+ years. The present value of a building that lasts 50 years is not that much different that the same one that lasts 100 years. With that in mind, it makes perfect sense to make an office building out of reinfor…

> The present value of a building that lasts 50 years is not that much different that the same one that lasts 100 years. That's a problem in and of itself, IMO. Construction is tremendously resource-intensive. We should not be building "throwaway" buildings.

A - The concept of present value isn't a problem, it's more like a fact, derived from the time value of money. It's like saying gravity is a problem.

B - Construction is resource intensive, no doubt about it. Without this technique the costs and resources would go up, double?, more? Many structures we take for granted, like freeway overpasses, would be impossibly expensive.

Re: The problem with reinforced concrete (2016)

#40

Post by GoToRO »

idoh wrote: post #18

I don't know if it is really a problem, more like a tradeoff. Reinforced concrete costs less and enables shapes that are impossible without it, with the downside that the buildings last 50 years instead of 100+ years. The present value of a building that lasts 50 years is not that much different that the same one that lasts 100 years. With that in mind, it makes perfect sense to make an office building out of reinfor…

I spoke with a builder, and the concrete starts to decay in 50 years. Until then it's like new. It lasts much longer than that, 100+ years is not a problem.
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