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 building, but often not much more. The simplest way to change this is to extend the design life, which would result in stainless steels or another more expensive material being used in this application.
Even stainless steel rusts, just more slowly. Roughly 10-100x more slowly, judging by https://www.nrc.gov/docs/ML1124/ML112490377.pdf and https://www.mdpi.com/2076-3417/10/23/8705/pdf.
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)
Simple, for externalities, you directly charge for the externality.
All these stop-gap "it costs carbon, so we must make it last 50 years" is like placing massive `if-then-else` statements throughout your codebase and then being surprised when the emergent behaviour of your program somehow results in uglier, more carbon polluting, sicker buildings that are now 100 years old and imposing massive costs on society around them.
Just FYI, on a ‘plan and spec’ construction project, all material is specified by the architect and engineers. If the project specs say you have to use stainless steel rebar, then even the low bidder will have it included.
What hubris for a landowner to assume there will be a need for a building 1000 years hence.
Buildings aren’t usually demolished and replaced because they are dilapidated; rather, it’s because the new owner has a different need (and a different aesthetic.)
A building that takes 1000 to crumble is just as a much a blight — maybe more — as a plastic bottle that takes 10,000 years to crumble.
The materials are important, but they can be misused, and master craftsmen can use them far better than I ever will, So the methods matter as well.
_edit_
I looked it up, hoover dam used steel pipes, not solid bars, so there's room for the corrosion to expand into the void created by the pipes.
Master craftsmen I tell ya, they think hard about that kind of stuff.
A flat roof, for example, is very prone to leaking, which when not constantly taken care of will wreck the building. Another is if the roof keeps water off of the walls (how big the overhang is). Many buildings have eaves that are an inch or two. The exterior walls of these buildings won't last.
Any building on a flat area near a river is going to flood. Any building without proper drainage around it is going to rot away.
Wood shingles need constant maintenance or goodbye to the building.
I've noticed manufacturing companies like big auto will try to solve for this by creating more specs for parts provided by suppliers but that's a losing battle as its always a race to the bottom. Plus now you need large testing teams to verify parts meet all these different specs. Maybe some percentage of the parts do - what do you in that case? The whole process can be a mess.
That claim seems to date to a particular article written in 2017 that wasn't well sourced. Roman concrete is interesting stuff and has useful properties, but humans have since created concrete mixtures that are far superior. But they're expensive, so it's not too surprising we don't see them getting used in buildings that compare less than favorably to a temple built a couple thousand years ago. Survivorship bias taken to the extreme.
I see two arguments against:
1. Future buildings will be so much better for the environment that increasing costs today for long lasting buildings or having to wait longer for environmentally better buildings is a net negative
2. Old buildings are typically not useful and so we shouldn’t encourage a future full of them (examples: smaller houses in city centres function ok but aren’t well insulated and could reduce total environmental costs of the city if they were replaced with more dense accommodation; many old churches see little use; many old buildings or rooms of them are no longer fit for any efficient purpose and so are wasting resources, eg banks with lots of space for tellers/vaults/deposit boxes or stock exchanges with big trading pits or warehouses which cannot be converted or even the rooms above shops which often seem to be disused. I have also seen other places where good use is still made of old buildings (typically long lived institutions like schools or societies or universities) though perhaps not as efficient use as might be possible. Obviously there are other cultural arguments for keeping old buildings around (but sometimes I worry regulations enforcing this can be too prohibitive, eg freezing an old building that has been changing slowly over many years at the point it becomes protected).
Construction specs often include “Allowed manufacturers” to limit your choices to certain vendors, which theoretically means you get quality material. For stainless steel, sometimes they’ll specify which alloy you need to use (304L and 316L are the most common) You certainly could submit the specified manufacturer’s product and then switch it out for a cheaper option, but if you’re caught, you could be forced to correct the work with the right material or be financially on the hook for another contractor performing the work. It would be up to someone else to notice that the steel contractor isn’t using the specified material, which may never happen.
The ‘use less of it than needed’ problem would ideally be caught by an inspector, but they certainly aren’t perfect.
Here’s a link to Cleveland Clinic’s electrical spec, if you’re curious how detailed they get: http://portals.clevelandclinic.org/Portals/57/2012_Elec%20Sp...
Japanese loathe “second hand” stuff if they can avoid it. This includes property. The service life for buildings is 47 to 50 years or so, for depreciation purposes.
Totally unrelated, but I love that 1000 year old wooden temples get rebuilt every 20 years or so[2] because of the religious idea of renewal.
[1] https://japanpropertycentral.com/2012/06/what-is-the-lifespa...
I think a good analogy world be eating healthy, you'll probably live longer then soon-to-be who doesn't eat healthy but in the end both will die and seize to exist.
Material science is incredibly interesting field and I think it will play a huge role in the future. It already does.
That doesn't tell you much: in the US the lifetime of a residential rental building is 27.5 years for depreciation purposes, and 39 for non-residential: https://www.irs.gov/publications/p946
Unless you’re talking about a very old house, this depends a lot on the local climate, construction materials, and design.
You can pretty successfully mitigate water entry with a dimple membrane and a gutter on an exposed wall, for example, and obviously this is a minimal concern if your house is in a desert.
(I’m not a trained architect, just someone interested in building science.)
My house has eaves that stick out about 2 feet. It added nothing significant to the cost, but boy what a difference it makes. The exterior walls almost never get wet. The windows and their frames stay dry and free of rot. No mildew. Haven't even needed to repaint.
There are a lot of things one can do with a house that, at trivial expense, will dramatically improve its life and lower maintenance costs.
Here's another one. Run the plumbing up interior walls. Then it won't freeze.
https://knifesteelnerds.com/2019/09/23/nitro-v-its-propertie...
But they all corrode, eventually. If you want a true corrosion-resistant metal that stays (kinda) sharp, look at one of the cobalt alloys like Stellite.
If you have a two-storey house in a wet area that gets a lot of storm activity coming from the northeast, for example, and you have an exposed northeast-facing wall, the eaves aren't going to do much to shield that wall from driving rain. You'd have to make sure it's dealt with in other ways.
> Here's another one. Run the plumbing up interior walls. Then it won't freeze.
Same with this - it might be good advice in Seattle, but if I told a local builder to worry about frost mitigation where I live now (Singapore) they'd probably question my sanity.
There's epoxy-coated rebar, but that's on the way out. Quebec has already banned it. One scratch, water gets in, and corrosion starts. Also, the epoxy can be damaged by UV, like when there's a stack of rebar out in the sun.
[1] https://www.outokumpu.com/en/products/long-products/rebar
My 95 year old brick house would beg to differ on utility of old buildings. My prior house was over 230 years old and provided 14 years of excellent utility to me.
Texas felt the same way until February!
cars that make many short trips, which never give the exhaust system time to fully warm up, often have extremely compromised exhaust systems, because the moisture simply can't be driven away effectively.
- dipping rebar in epoxy is sometimes done, but a single nick in the coating causes all the erosion to concentrate in that one spot, so it can be more dangerous than just uncoated rebar
- galvanised rebar works much better than epoxy, and resists corrosion at lower pH levels than normal iron, but may result in more metal loss under some conditions
- sacrificial anodes (as per the article) can and are used, but exactly how is quite complicated: if they're embedded in the concrete, the zinc breaks down into substances that can weaken it
- concrete is naturally alkaline, with cement being manufactured partly from lime, and this protects the rebar, but too high a pH causes other problems in the concrete itself, so you can't just dump alkaline substances into the mixture forever
- you can apparently use fibreglass as rebar, but I have no idea if it's any good, or what happens to fibreglass if you leave it embedded in concrete for a century
Modern concretes can do a whole lot of stuff Roman concrete can't, because there are so many formulations of it. But if you want to stick a building literally in the ocean and have it never ever disappear, nobody has shown that we can actually do it today.
There's a whole lot of theory and talk by experts, about how we don't need to make it, but if we wanted to, boy would it be easy, but don't worry, modern concrete is just so amazing, you should just use that, for modern use cases, and oh by the way, it would be too expensive to make, even though we haven't actually made it or tried to bring the price down.
There's a world of practical experience needed to claim for a fact that modern concrete is legitimately better, much less that we can actually make it and that it would hold up as we expect. I'm still waiting for concrete evidence.
Btw were Deloreans pretty rust resistant? How will the cyber truck do living by the beach?
"A recent innovation in the Japanese real estate industry to promote home ownership is the creation of a 100-year mortgage term. The home, encumbered by the mortgage, becomes an ancestral property and is passed on from grandparent to grandchild in a multigenerational fashion. We analyze the implications of this innovative practice, contrast it with the conventional 30-year mortgage popular in Western nations and explore its unique benefits and limitations within the Japanese economic and cultural framework." The 100-year Japanese residential mortgage: An examination (1995) (https://www.sciencedirect.com/science/article/abs/pii/106195....)
[1]https://www.thelocal.se/20160324/sweden-limits-mortgage-loan...
That said, I can almost guarantee the specs for automotive manufacturers are less strict and the penalties less severe simply because the specs are made to be cost-centric rather than performance-centric.
/Acey
And I have a friend who lives in Texas. The pipes in the outer walls froze and burst, the ones in the inner walls did not.
Jeez, of course one pays attention to the local climate. I don't worry about tornadoes in Seattle, but would if in the midwest.
This description is fairly accurate. The CaCO3 (used as a source of calcium in the cement component of concrete) is completely decarbonated in a 1450°C kiln in the process of cement manufacture, combined with silica (from shale) +/- SO4 (from gypsum) and sintered to form an anhydrous calcium silicate (clinker: e.g. tricalcium silicate, Ca3SiO5, ‘alite’), then powdered (e.g. ordinary Portland cement, OPC). The skeletal limestone is long gone — and the above decarbonation step is the reason cement manufacturing process is a significant GHG source (in addition to fuel consumption by the kiln itself).
Mixing water with the powdered clinker generates a very rapid, exothermic, partial dissolution of the primary silicate. The rapid release of silica results in nucleation and growth of calcium silicate hydrate (CSH) plus Ca(OH)2. CSH binds the remaining unreacted solid mass together, giving cement its durability and strength.
Believe it or not, this kind of thing isn't just immediately obvious to everyone.
The bigger difference in components is the kind of cement the Romans (and we "moderns" until a few years ago) used, i.e. pozzolanic cement, nowadays everything is "portland" cement.
BUT the definite difference is the kind of structures, Romans did not use "reinforced" concrete, only various types of "plain, non-reinforced" concrete, and all their structures are based on the main characteristic of concrete, which is its resistance to compression.
The idea of reinforced concrete is all about adding to a material with excellent compression resistance (but no resistance on tension/traction) a material (steel) with excellent resistance to tension/traction and relatively poor (in the quantities used in reinforced concrete) resistance to compression, obtainining a composite material that excels in both.
About ashes, overall it is more about their size that about their nature, concrete is a composite and if you have all possible sizes of aggregates (ashes are very, very small sized particles) in the "right" amount you essentially fit "better" the space, i.e. you have a higher density of the resulting composite, and, particularly when compression resistance is the goal, the higher the density the better the resistance.
Imagine (say) that you have to fill a 100x100x100 mm box with 10 mm balls, you can fit in them a certain amount of these balls (roughly 10x10x10=1000), but you are leaving lots of "air" between them, a single 10 mm ball is 2/3x3.1416x5^3=262 mm3, so the 1000 balls total 262,000, but the volume of the box is 100x100x100= 1,000,000, now if you have some 2 mm balls you can add them in the same volume, and then if you have some 0.5 mm balls you can put some of them in that same box as well, etc.
I don't think this stops these new products from being used, it's just another engineering tradeoff.
I contend that buildings, with a few exceptions, are consumables. Whether wise or not, humans like to build new things, customizable to their own tastes.
An office building that lasts ‘only’ 50 years instead of 500 shouldn’t be surprising. In 50 years time, for most buildings, even if it could last another few decades, it will be torn down and replaced. That’s just what humans do. States differently, even if everyone at the time knew concrete/rebar would only last 50 years and not the 1000+ years, it wouldn’t have made a difference, for nobody — short of a Pharaoh — has any interest in such a permanent structure. Cities come and go, buildings come and go, rivers and shorelines change, etc. it’s not reasonable to assume the desirable center of activity (either residential or commercial) in which one builds will even be there 50 years hence. So why worry about how long the building will last?