I used to be structural engineer, and while things may have changed in the past 8 years since I left, I doubt it.
The problem with structural engineering is incentives. It is one of the reasons that I left. Most structural engineering companies are filled with conservative, boring engineers that prefer to look up pre-designed segments and don't make full use of the steel design handbook or building codes.
For example, in Canada if you have a non-load bearing brick outer face (most brick buildings in Canada) you're allowed to reduce the wind load by 10%. I was the only person I knew that knew this because I actually read the steel, concrete, and wood design handbooks front to back while I made notes. Furthermore almost nobody has read the building code "just because" they might hop to a section here or there when they need it, but they're generally not going to just sit down and read the thing.
So when I would design buildings I would be able to take advantage of a lot more things than most people. This lead to my buildings being cheaper / easier to build, which of course lead to our engineering fees looking like a larger portion of the job.
The problem with reinforced concrete is the same. Engineers have no financial incentive to make alterations to their designs to make the buildings last longer. It is almost trivial to make sure steel wont rust (or to double or triple a buildings life) but it makes construction costs go up 0.01% and makes engineerings fees go up 0.1% so nobody does it. Regulators are to blame too. There are amazing concretes (Ultra High Performance Concretes) we should be using in our buildings that completely lack even needing steel because they are so ductile and strong (MPa 200 for the one I was familiar with, Ductal by Lafarge), but it's impossible to use in construction in Canada because the code is so rigid.
> Most structural engineering companies are filled with conservative, boring engineers that prefer to look up pre-designed segments and don't make full use of the steel design handbook or building codes.
I dare say the same is true of software engineering. I, nominally a backend engineer, know (and apply) more about HTTP than most front-end devs and architects I've met, simply because I sat down one day and read the HTTP spec. (It's not a difficult read!)
I'd just like to mention one counter argument, which the rigidity of the code in some cases will help to protect against developers from using cheaper materials, or new materials that on paper seem better, but in reality may not be better.
An example I've heard of but am having trouble searching for the exact name, is in condo buildings here in Canada they started using a new piping material, to do the water deliver inside the units. The problem was, while I think in theory the material was better, it has the property that when it fails it fails catastrophically, due to either a manufacturing or installation defect. So instead of just having a small pinhole leak, the piping will split when compromised, and you have many thousands of dollars in damages to multiple units. Buildings with this material can no longer be insured in Canada.
So I don't know that I would really trust giving developers a wide latitude in selecting materials, even if they sound great on paper.
I don't know what the solution is, because I agree we need to be more flexible, and have a way to introduce new and better technologies, but we also have to be diligent, in ensuring that the new technologies and processes work the way we expect them to, and have the desired effects.
I don't really understand why you left. I would have loved to employ someone like you back when I needed a structural engineer. You had an opportunity to make a lot of money by shining head and shoulders above your competition.
The only problem I see is a marketing issue - being able to get the message out to your customers of the advantages of going with your firm.
"...which of course lead to our engineering fees looking like a larger portion of the job."
So there you go. Mismeasurement is 99% of all business problems. I've been laid off before because I didn't generate the (apparently) required level of software defects and missed a gate or two by a day or two doing it. I was actually told I didn't look busy enough.
If most are unaware of it, is it then good practice (aka insurance) for you to cite the relevant codes in your plans, in order to avoid trouble by inspectors due to the differences, or is it safe to expect an inspector to know the codes A-Z?
You've identified a fantastic application of AI, when the technology gets there. A machine can read all the codes with better retention and would have the patience to make these optimizations. A human in the loop could offload some of the judgement-intensive aspects.
That's one problem with government regulations. Even when they're actually well designed and impartial, they don't get updated when technology changes.
After a few decades, the once great regulations are often way out of date.
I'm not in construction or an engineer but when I was watching Mike Holmes he said the "code" (building code) really means minimum building code. I had never really thought of it like that before it was a good point why strive for minimum?
You can build better there's no reason you can't (cost obviously) but most people just aim to barely pass minimum building code.
"This lead to my buildings being cheaper / easier to build, which of course lead to our engineering fees looking like a larger portion of the job."
I propose you could start a consulting gig and maybe your own firm. Can't be that there aren't people who want their buildings to be cheaper for the same quality.
This article has many problems. Most importantly, building techniques such as "steel frame", "traditional bricks and mortar", "mud brick" and "rammed earth" are far less capable than reinforced concrete. The article implies that as these are more "durable" they are superior to reinforced concrete. This is a false equivalence of staggering magnitude. Reinforced concrete is the great enabler of modern high-rise construction and civil engineering; most projects simply would not be able to be built without reinforced concrete. Without reinforced concrete the world would be a very different place.
I take special issue with the article's use of pseudoscientic false analogies.
> This means that concrete structures, for all their stone-like superficial qualities, are actually made of the skeletons of sea creatures ground up with rock. It takes millions upon millions of years for these sea creatures to live, die and form into limestone. This timescale contrasts starkly with the life spans of contemporary buildings.
This is utter drivel.
There is a valid point in that for smaller scale constructions other techniques may be applicable which are otherwise ignored; also that there are alternatives to steel as the reinforcing material, both for prestressed structures and not.
I read an engineering guideline on concrete that I wish I could find. It compared the economics of building a steel vs reinforced concrete bridge. Steel came out better when you considered the lifetime and especially the recyclability, but concrete was cheaper to build initially. The steel bridge would last indefinitely, as long as you kept it painted, or even replaced rusted parts.
Reinforced concrete is costly to demolish, and nearly impossible to recycle. Crushed concrete can be used as a filler, but in order to be used for fresh concrete it must be free of contaminates, which is rarely the case, and no one wants to risk the integrity of a new structure of any importance.
The percentage of all concrete structures even built, that are still standing must be quite large. This will not be a great legacy to leave future generations.
We're not running out of limestone anytime soon, but otherwise this is a bit off-target. All of the alternative construction techniques you mention have advantages over reinforced concrete. Concrete also has its advantages, but TFA is not wrong about the disadvantages.
When I traveled to Philippines earlier this year I was struck by how they use masonry in situations that in USA would be reinforced concrete. Granted, the blocks are all CMUs, but the technique is masonry. I think it's because very few roads (at least in the places I traveled) would be suitable for standard 6-yard concrete trucks, whereas you can always throw a few dozen blocks on the back of a motorcycle. Of course labor costs are also a factor. However, concrete in block form is totally recyclable, while as TFA notes when poured it is not.
I'm a civil engineer. This is bullshit. Reinforced concrete uses much less concrete because, well, you have rebar to take care of tensile stresses and concrete does well with compression so it's much more efficient, which is basic. Also, and a very important point, reinforced concrete (in general) tends to fail in non-catastrophic ways making it safer to use and easier to spot conceptual errors in the project and building process. Reinforced concrete can also be recycled, the concrete becomes structural blocks (I even worked with these before) and the rebar is steel so thats easily recycleable too. In the end, it's cheap and affordable so you can build much more with reinforced concrete than with concrete reinforced with carbon fiber which would last forever but would cost a fortune (this can also be used to reinforce reinforced concrete...) making housing unaffordable to a large part of the world. Do you also really want to spend that much more to make a project to last 500 years without using reinforced concrete? You know that goes into the equation when engineers project strucures right? Oh well, clickbait.
The point is that longer-lasting structures should be cheaper, but because we don't factor in environmental harm and lifecycle cost into the price of things we end up with cheap buildings that exist to generate ROI ASAP.
As an aside, fiberglass (similar to carbon fiber) is used frequently (but still not much, relative to steel) in many applications. We use it extensively in underground applications.
The problem with fiberglass reinforcement is that it does not undergo ductile failure like steel does. Steel will yield and, in addition, has strain hardening behavior. Fiberglass just fractures and that's that. Extra precautions must be taken when using fiberglass in failure critical members.
Why not just use straw, instead of carbon fiber, in concrete? Straw is comparable to steel. Chopped straw is used for stucco, but it can be used in reinforced concrete too.
It is hard to calculate amount of straw, which is necessary to reinforce concrete, because it strength varies, but it cheap, so just triple amount of straw.
This article makes an interesting comparison to ancient Roman concrete. While the Romans built a tremendous amount of infrastructure in concrete, survivorship bias means that the few bits that have hung around are seen as some sort of superior quality to Roman understanding of concrete.
However, if you go to Rome, most of the surviving bits are millions upon millions of stacked and mortared bricks, and most of what has survived are uninteresting walls. [1] For some reason, our collective memory of Roman ruins is that they're all aged concrete or stone. But when in Rome, you end up seeing lots of this [2], which when built probably had a layer of facade material on it.
And it makes sense, stacked, weather resistant, often covered in a prettier facade, baked bricks should last more or less forever until the elements wear them down.
The widespread reintroduction of concrete as a building material really didn't happen until around the turn of the 20th century. And reinforced concrete didn't find widespread use until a few decades after that. Not particularly confusing, the first generations of buildings built with these fairly new and only partially understood materials are the buildings that the author is mostly writing about.
The real culmination of exposed, reinforced-concrete-everywhere, finally happened in the 50s with the advent of the eye cancer called brutalism. Today a tremendous number of brutalist buildings today are absolutely falling apart, and I blame that on a lack of understanding of how reinforced concrete should be used and the availability of more modern materials and perhaps an overenthusiasm and misuse of materials where they shouldn't have been.
But still, if we fast forward a thousand years, there's bound to be a percentage of those structures still around and survivorship bias in the future will lead some to speculate that the engineers of the 20th century were geniuses unrivaled by any in the future.
Roman concrete holds up against the erosive properties of seawater better than the materials used today. Scientists discovered it's because they used volcanic ash to make their concrete.
More realisticly zero steel reinforced concrete structures will survive, but other types of buildings might. The house I grew up in for example is pushing 300 years old. That's still a long way to go, but the older it gets the more likely it is to be preserved. A 90% chance it survives any given 50 years = 2-3% chance it makes 1900.
Just an aside, the Colosseum, long held up as an example of superior Roman concrete construction, is mostly brick as well...which I found infinitely surprising when I finally had a chance to visit it. [1]
Here's a walk around the structure [2], it's virtually all brick.
The very first sentence of this article is a giant red flag, the comparison between the Pantheon in Rome and modern concrete is deeply misleading -- Roman concrete was a different material than modern Portland-cement/sand/gravel scheme, it had better resistance to cracking and could set under water. [1]
The rest of the article seems to be, if you think on different time-scales and use different cost-benefit criteria (e.g. include or exclude environmental effects), you get different answers about the suitability of various materials. This is indisputably true.
Modern concrete can set underwater, and, at least for concrete where you care about the results, you want to keep the surface wet until the concrete cures appropriately.
(IANAPE, but I took a grad level concrete course in school)
addition/edit: Quick primer. When concrete cures, it's a chemical process that converts free water into an electrostatic gel in the cement crystals. That interlocks the small and large aggregate to make a solid. If concrete dries rather than cures, then that gel doesn't form and you don't get the gel holding it together. If you heat up cured concrete enough, you'll drive out the water and make it a powder again.
If you cure something under water, it can technically continue to cure for a very long time. Normally you keep it moist for 24-48 hours, and standard testing is done at 28 days. That will get you something like 90% of the final strength, if it can continue to cure indefinitely. I've tested concrete that was semi-submerged for 40 years where the design strength was 4ksi, and it tested out at 14ksi.
I see a lot of engineers calling the article FUD and BS, what with it mentioning ancient Roman buildings and mud bricks.
I also see several commenters (myself included) wholeheartedly agreeing with the point it makes.
I think bluthru hit the nail on the head somewhere below (which will soon be above?)
> The point is that longer-lasting structures should be cheaper, but because we don't factor in environmental harm and lifecycle cost into the price of things we end up with cheap buildings that exist to generate ROI ASAP.
Factoring in those kinds of costs runs contrary to mainstream economic doctrine, so the question really is whether you think that capitalism (in its current form) is doing more harm than good for our communities and/or for our species as a whole, especially including future generations.
An alternative to steel for concrete reinforcement is glass blown basalt [0], which struck my interest via its use in a project for free-floating, (geopolymer) concrete seasteading vessels [1].
The depressing counterpoint, I suppose, is that 99% of the time, you're not building the Pantheon, you're building something that was intended to be minimally-acceptable, utilitarian, and disposable from the get-go: a parking garage, a tilt-up big-box building, a freeway on-ramp, a strip mall. All of which may well be obsolete in a few decades just because the urban environment changes rapidly.
If you could figure out a systematic way to cut the cost and the lifetime of such lowbrow, mass-produced concrete structures in half, developers wouldn't hesitate, they'd jump on it immediately.
This article is full of FUD. What is the alternative? All these reinforced concrete problems are well understood and studied. if proper construction and design codes and maintenance guidelines are followed these structures can last a very long time.
In europe we have EuroCodes that account for this problems and to my knowledge concrete cancer is not related with steel corrosion but with a long term chemical reaction between some aggregates and cement. Remember that concrete is cement with sand and stones and the hardning chemical reactions are complex and can last for decades.
The only salient point this article mentions (but only briefly) is that concrete production generates a huge amount of CO2. Everything else is hogwash. In terms of strength, versatility, and cost, steel-reinforced concrete has proven to be the greatest building material humans have ever devised. It is by no means perfect, but nothing is. Concrete needs to be maintained just like anything else. With neglect it decays.
I'm a fan of brutalism, so I do like concrete buildings and find them interesting, but there's also a good case to be made about mud bricks, which the author aludes to. Yes, you'll have issues building 10-storey high buildings out of mud-bricks, but it's definitely possible to build structures (like barns) out of them that can easily last more than 100 years, without the builder having to have a civil engineering degree. I've seen one such structure with my one eyes, built by my grand-grand-father who was a peasant. The only thing you have to be careful about when building stuff out of earth is water infiltrations, otherwise you're good.
Buildings made out of earth are also better heat insulators compared to concrete. My grandma's house was always cool in the summer, while my appartment which is part of a building made out of concrete wouldn't be livable in the summer without AC.
Ongoing maintenance is an important energy and money sink for any society. I find it doubtful that concrete (at least, the modern versions and usage of it) will be sustainable beyond the fossil fuel era, simply because it will be too expensive to maintain.
EROEI for a given bit of infrastructure (ie how much energy is conserved or produced for a given energy expenditure in construction/maintenance) isn't as sexy, but it's just as much a thermodynamic constraint on sustainability as overusing the CO2 capacity of the oceans and atmosphere.
The real question is do we want buildings to survive 200 years? In 200 years building technology might have advanced far enough that everything is carbon fiber concrete or something far superior. People look at degradation of a structure as some kind of serious issue, but it can also be seen as a positive.
Surprised they didn't mention carbonatation and climate chance. tl;dr rising partial pressure of CO2 in the air leads to a spontaneous "reverse calcination" process, lowering the pH which leads to rebar failure. By 2050 most reinforced concrete buildings will be effected.
I haven't been a practicing engineer since 2007 but if my memory serves me well, to avoid problems of corrosion one often used method was to increase the cover [0](distance from concrete surface to top of steel reinforcement using spacers). I can't see it mentioned anywhere in the article, will probably have to re read it...
Where I live there's a huge number of apartment blocks, most of them built in 60s and onwards, and the apartments are the sole place to live and the prime asset for most people.
They'll definitely start crumbling in a few decades and not many people will be able to afford a new home as well as deprecation of their main asset. Have no idea how this might ever resolve, frankly.
[+] [-] 3pt14159|9 years ago|reply
The problem with structural engineering is incentives. It is one of the reasons that I left. Most structural engineering companies are filled with conservative, boring engineers that prefer to look up pre-designed segments and don't make full use of the steel design handbook or building codes.
For example, in Canada if you have a non-load bearing brick outer face (most brick buildings in Canada) you're allowed to reduce the wind load by 10%. I was the only person I knew that knew this because I actually read the steel, concrete, and wood design handbooks front to back while I made notes. Furthermore almost nobody has read the building code "just because" they might hop to a section here or there when they need it, but they're generally not going to just sit down and read the thing.
So when I would design buildings I would be able to take advantage of a lot more things than most people. This lead to my buildings being cheaper / easier to build, which of course lead to our engineering fees looking like a larger portion of the job.
The problem with reinforced concrete is the same. Engineers have no financial incentive to make alterations to their designs to make the buildings last longer. It is almost trivial to make sure steel wont rust (or to double or triple a buildings life) but it makes construction costs go up 0.01% and makes engineerings fees go up 0.1% so nobody does it. Regulators are to blame too. There are amazing concretes (Ultra High Performance Concretes) we should be using in our buildings that completely lack even needing steel because they are so ductile and strong (MPa 200 for the one I was familiar with, Ductal by Lafarge), but it's impossible to use in construction in Canada because the code is so rigid.
[+] [-] colanderman|9 years ago|reply
I dare say the same is true of software engineering. I, nominally a backend engineer, know (and apply) more about HTTP than most front-end devs and architects I've met, simply because I sat down one day and read the HTTP spec. (It's not a difficult read!)
[+] [-] kevin_nisbet|9 years ago|reply
I'd just like to mention one counter argument, which the rigidity of the code in some cases will help to protect against developers from using cheaper materials, or new materials that on paper seem better, but in reality may not be better.
An example I've heard of but am having trouble searching for the exact name, is in condo buildings here in Canada they started using a new piping material, to do the water deliver inside the units. The problem was, while I think in theory the material was better, it has the property that when it fails it fails catastrophically, due to either a manufacturing or installation defect. So instead of just having a small pinhole leak, the piping will split when compromised, and you have many thousands of dollars in damages to multiple units. Buildings with this material can no longer be insured in Canada.
So I don't know that I would really trust giving developers a wide latitude in selecting materials, even if they sound great on paper.
I don't know what the solution is, because I agree we need to be more flexible, and have a way to introduce new and better technologies, but we also have to be diligent, in ensuring that the new technologies and processes work the way we expect them to, and have the desired effects.
[+] [-] WalterBright|9 years ago|reply
The only problem I see is a marketing issue - being able to get the message out to your customers of the advantages of going with your firm.
[+] [-] ArkyBeagle|9 years ago|reply
So there you go. Mismeasurement is 99% of all business problems. I've been laid off before because I didn't generate the (apparently) required level of software defects and missed a gate or two by a day or two doing it. I was actually told I didn't look busy enough.
[+] [-] cm3|9 years ago|reply
[+] [-] paulsutter|9 years ago|reply
I wonder what's the MVP?
[+] [-] BurningFrog|9 years ago|reply
After a few decades, the once great regulations are often way out of date.
[+] [-] dghughes|9 years ago|reply
You can build better there's no reason you can't (cost obviously) but most people just aim to barely pass minimum building code.
[+] [-] guard-of-terra|9 years ago|reply
I propose you could start a consulting gig and maybe your own firm. Can't be that there aren't people who want their buildings to be cheaper for the same quality.
[+] [-] spraak|9 years ago|reply
[+] [-] dkbrk|9 years ago|reply
I take special issue with the article's use of pseudoscientic false analogies.
> This means that concrete structures, for all their stone-like superficial qualities, are actually made of the skeletons of sea creatures ground up with rock. It takes millions upon millions of years for these sea creatures to live, die and form into limestone. This timescale contrasts starkly with the life spans of contemporary buildings.
This is utter drivel.
There is a valid point in that for smaller scale constructions other techniques may be applicable which are otherwise ignored; also that there are alternatives to steel as the reinforcing material, both for prestressed structures and not.
[+] [-] euroclydon|9 years ago|reply
Reinforced concrete is costly to demolish, and nearly impossible to recycle. Crushed concrete can be used as a filler, but in order to be used for fresh concrete it must be free of contaminates, which is rarely the case, and no one wants to risk the integrity of a new structure of any importance.
The percentage of all concrete structures even built, that are still standing must be quite large. This will not be a great legacy to leave future generations.
[+] [-] jessaustin|9 years ago|reply
When I traveled to Philippines earlier this year I was struck by how they use masonry in situations that in USA would be reinforced concrete. Granted, the blocks are all CMUs, but the technique is masonry. I think it's because very few roads (at least in the places I traveled) would be suitable for standard 6-yard concrete trucks, whereas you can always throw a few dozen blocks on the back of a motorcycle. Of course labor costs are also a factor. However, concrete in block form is totally recyclable, while as TFA notes when poured it is not.
[+] [-] schiffern|9 years ago|reply
It's utter drivel to point out that nonrenewable resources are being squandered at a shocking rate on structures that can't even last a century?
[+] [-] fpaboim|9 years ago|reply
[+] [-] bluthru|9 years ago|reply
[+] [-] abduhl|9 years ago|reply
The problem with fiberglass reinforcement is that it does not undergo ductile failure like steel does. Steel will yield and, in addition, has strain hardening behavior. Fiberglass just fractures and that's that. Extra precautions must be taken when using fiberglass in failure critical members.
[+] [-] lisivka|9 years ago|reply
[+] [-] guard-of-terra|9 years ago|reply
I'm just so happy that people had different perspective back then.
It's sad that we don't understand - unsustainable growth, scaffolding and prototyping phase is long overdue.
[+] [-] bane|9 years ago|reply
However, if you go to Rome, most of the surviving bits are millions upon millions of stacked and mortared bricks, and most of what has survived are uninteresting walls. [1] For some reason, our collective memory of Roman ruins is that they're all aged concrete or stone. But when in Rome, you end up seeing lots of this [2], which when built probably had a layer of facade material on it.
And it makes sense, stacked, weather resistant, often covered in a prettier facade, baked bricks should last more or less forever until the elements wear them down.
The widespread reintroduction of concrete as a building material really didn't happen until around the turn of the 20th century. And reinforced concrete didn't find widespread use until a few decades after that. Not particularly confusing, the first generations of buildings built with these fairly new and only partially understood materials are the buildings that the author is mostly writing about.
The real culmination of exposed, reinforced-concrete-everywhere, finally happened in the 50s with the advent of the eye cancer called brutalism. Today a tremendous number of brutalist buildings today are absolutely falling apart, and I blame that on a lack of understanding of how reinforced concrete should be used and the availability of more modern materials and perhaps an overenthusiasm and misuse of materials where they shouldn't have been.
But still, if we fast forward a thousand years, there's bound to be a percentage of those structures still around and survivorship bias in the future will lead some to speculate that the engineers of the 20th century were geniuses unrivaled by any in the future.
1 - http://previews.123rf.com/images/13th/13th0902/13th090200009...
2 - http://farm6.staticflickr.com/5185/5762585618_10a11f5a38_z.j...
[+] [-] godzillabrennus|9 years ago|reply
http://newscenter.lbl.gov/2013/06/04/roman-concrete/
[+] [-] Retric|9 years ago|reply
[+] [-] bane|9 years ago|reply
Here's a walk around the structure [2], it's virtually all brick.
[1] [2] https://www.youtube.com/watch?v=uWkct044pFU
[+] [-] reidacdc|9 years ago|reply
The rest of the article seems to be, if you think on different time-scales and use different cost-benefit criteria (e.g. include or exclude environmental effects), you get different answers about the suitability of various materials. This is indisputably true.
[1] https://en.wikipedia.org/wiki/Roman_concrete
[+] [-] wiredfool|9 years ago|reply
(IANAPE, but I took a grad level concrete course in school)
addition/edit: Quick primer. When concrete cures, it's a chemical process that converts free water into an electrostatic gel in the cement crystals. That interlocks the small and large aggregate to make a solid. If concrete dries rather than cures, then that gel doesn't form and you don't get the gel holding it together. If you heat up cured concrete enough, you'll drive out the water and make it a powder again.
If you cure something under water, it can technically continue to cure for a very long time. Normally you keep it moist for 24-48 hours, and standard testing is done at 28 days. That will get you something like 90% of the final strength, if it can continue to cure indefinitely. I've tested concrete that was semi-submerged for 40 years where the design strength was 4ksi, and it tested out at 14ksi.
[+] [-] etatoby|9 years ago|reply
I also see several commenters (myself included) wholeheartedly agreeing with the point it makes.
I think bluthru hit the nail on the head somewhere below (which will soon be above?)
> The point is that longer-lasting structures should be cheaper, but because we don't factor in environmental harm and lifecycle cost into the price of things we end up with cheap buildings that exist to generate ROI ASAP.
Factoring in those kinds of costs runs contrary to mainstream economic doctrine, so the question really is whether you think that capitalism (in its current form) is doing more harm than good for our communities and/or for our species as a whole, especially including future generations.
Do you?
[+] [-] jpt4|9 years ago|reply
[0] http://basalt-rebar.com/
[1] https://www.reddit.com/r/Floathouse/
[+] [-] Eric_WVGG|9 years ago|reply
http://www.pnas.org/content/111/52/18484.abstract
For laypersons http://www.dailymail.co.uk/sciencetech/article-2877547/Why-C...
[+] [-] Lagged2Death|9 years ago|reply
If you could figure out a systematic way to cut the cost and the lifetime of such lowbrow, mass-produced concrete structures in half, developers wouldn't hesitate, they'd jump on it immediately.
We revere longevity only in retrospect.
[+] [-] nusq|9 years ago|reply
In europe we have EuroCodes that account for this problems and to my knowledge concrete cancer is not related with steel corrosion but with a long term chemical reaction between some aggregates and cement. Remember that concrete is cement with sand and stones and the hardning chemical reactions are complex and can last for decades.
[+] [-] schiffern|9 years ago|reply
It's called carbonatation, it reduces the concrete's pH which leads to rebar failure, and it's only going to get worse with climate change.
https://en.wikipedia.org/wiki/Carbonatation
[+] [-] greydius|9 years ago|reply
[+] [-] paganel|9 years ago|reply
Buildings made out of earth are also better heat insulators compared to concrete. My grandma's house was always cool in the summer, while my appartment which is part of a building made out of concrete wouldn't be livable in the summer without AC.
[+] [-] schiffern|9 years ago|reply
Ongoing maintenance is an important energy and money sink for any society. I find it doubtful that concrete (at least, the modern versions and usage of it) will be sustainable beyond the fossil fuel era, simply because it will be too expensive to maintain.
EROEI for a given bit of infrastructure (ie how much energy is conserved or produced for a given energy expenditure in construction/maintenance) isn't as sexy, but it's just as much a thermodynamic constraint on sustainability as overusing the CO2 capacity of the oceans and atmosphere.
[+] [-] jorblumesea|9 years ago|reply
[+] [-] schiffern|9 years ago|reply
https://www.bostonglobe.com/ideas/2014/10/11/for-concrete-cl...
https://en.wikipedia.org/wiki/Carbonatation
http://ec.europa.eu/environment/integration/research/newsale...
[+] [-] RP_Joe|9 years ago|reply
[+] [-] lisivka|9 years ago|reply
[+] [-] foxhop|9 years ago|reply
Rammed earth has great thermal mass which has huge benifits if controlled.
[+] [-] ChrisNorstrom|9 years ago|reply
[+] [-] wilsonfiifi|9 years ago|reply
[0] http://www.buildinghow.com/en-us/Products/Books/Volume-A/The...
[+] [-] jhallenworld|9 years ago|reply
[+] [-] combatentropy|9 years ago|reply
[+] [-] guard-of-terra|9 years ago|reply
They'll definitely start crumbling in a few decades and not many people will be able to afford a new home as well as deprecation of their main asset. Have no idea how this might ever resolve, frankly.