[HN Gopher] On Geofoam
___________________________________________________________________
On Geofoam
Author : andyjohnson0
Score : 77 points
Date : 2021-07-29 13:24 UTC (9 hours ago)
(HTM) web link (theprepared.org)
(TXT) w3m dump (theprepared.org)
| modeless wrote:
| The landscapes built with this stuff are temporary. But the stuff
| itself is permanent. As the earth on top erodes away it will be
| exposed in ugly dead patches like open sores, and eroded itself
| until it's spread all over the surrounding area as particles
| mixed with the dirt. But hey, for a hundred years or so some
| landscape architect's vision of hills will be fulfilled, at a
| lower cost!
|
| What a waste.
| jart wrote:
| Why is it temporary? The paper the OP linked says "the overall
| results form the monitoring programme indicate that [geofoam]
| behaves as expected and that the selected design parameters
| provide stable and satisfactory structures for long time
| performance"[1]
|
| It looks more like a national security issue. If we're ever at
| war then the enemy can always tip over a jug of petroleum ether
| to turn our deeply embedded geofoam foundations into glue,
| which I imagine would cause everything built on top to crumble
| too. It would appear they're mostly building highways using
| this stuff (rather than skyscrapers) so that shouldn't be too
| much of a vulnerability but it probably isn't what Dwight
| Eisenhower had in mind when he built the interstates.
|
| [1] Aaboe R, Frydenlund TE (2011) 40 years of experience with
| the use of EPS geofoam blocks in road construction. Paper
| presented at the 4th international conference on geofoam blocks
| in construction applications, Lillestrom, Norway, 6-8 June 2011
| Arrath wrote:
| Well, I find it questionable to build roadway/infrastructure
| foundations out of something vulnerable to structural
| degradation from exposure tp petroleum products.
|
| One wreck involving a fuel tanker without sufficient
| containment and the entire subgrade starts to dissolve and
| buckle and sink?
| modeless wrote:
| All landscapes are temporary. The earth changes.
|
| What is a "long time"? Is it one human lifetime? The time
| period in which these blocks will be a blight is a whole lot
| longer than the time period where they make a nice landscape,
| it's just that the nice landscape part comes first. Should we
| do anything we want assuming that what happens after we're
| dead is irrelevant?
| jart wrote:
| I replied to your comment because I agree with you but I
| couldn't find any information online to support it. I cited
| research where they studied foam that's been in place for
| 40+ years and it's fine. I was hoping you had data that
| would support what we both want to hear.
| bsza wrote:
| > Geofoam blocks can contain some percentage of recycled plastic,
| and the blocks themselves are marketed as recyclable
|
| So instead of using some of the millions of tons of existing
| styrofoam waste as landfill they produce brand new styrofoam and
| put that in there instead? Did I get that right?
| ISL wrote:
| If one could create geofoam from sequestered carbon, I suspect
| almost everyone would be in favor.
| newbamboo wrote:
| It's funny to think of those who would oppose it. There are
| actually many, like the poster who is concerned about
| biodegradability. It can't sequester carbon if it also
| biodegrades. "Split wood, not atoms!"
| goodpoint wrote:
| > It can't sequester carbon if it also biodegrades
|
| This is misleading. Trees in a forest store carbon as long as
| the forest exists. Individual trees might degrade (or be
| trapped underground), but new ones are born.
| nerdponx wrote:
| So is Geofoam a contributor to microplastic pollution or not?
| falcolas wrote:
| Over time, there's no reason it _wouldn 't_. It's expanded
| polystyrene with an eco-friendly name, and anything that
| would degrade EPS would degrade these blocks. Groundwater
| is the big one I'd be concerned about. It being dug up and
| trashed by future earthworks projects would be the second
| big thing.
| kennywinker wrote:
| And yet all of the sequestered carbon we are tossing into the
| air in the form of burning fossil fuels was once biodegrading
| organic matter... it's almost like "biodegrade" and
| "sequester" can coexist.
| MisterTea wrote:
| > It can't sequester carbon if it also biodegrades.
|
| How does biodegrading release carbon?
| cmrdporcupine wrote:
| Natural biodegradation usually releases at least part of
| the carbon via CO2.
| goodpoint wrote:
| Environmental impact is complex and has multiple dimensions.
| Obsessing over carbon is dangerous.
| ggcdn wrote:
| We use this a lot to support landscaping in the sky (rooftop
| terraces and such on high rises) which is an architectural trend
| that really needs to go away. There is nothing green or
| sustainable about the extra concrete needed to support it.
|
| But the alternative to geofoam is usually clean fill, like sand,
| which weighs about 110 lb/cf. contractors ask to substitute it
| because it's cheaper, but it almost always results in thicker
| structure and more rebar to support it.
| BugsJustFindMe wrote:
| > _But the alternative to geofoam is usually clean fill, like
| sand, which weighs about 110 lb /cf._
|
| Why not aircrete?
| ggcdn wrote:
| Not sure, it's not been proposed on our projects before. Most
| likely, that means it's not cheaper than geofoam or fill.
| baybal2 wrote:
| Very likely it's just no contractors dealing with it.
|
| I read up on it when we did electronics for concrete
| mixers.
|
| The chemistry of foam concrete is a very inexact science,
| bordering on being "possible to get right through talent
| only"
|
| Very little literature on it, and proprietary foaming
| agents all come from Eastern Europe with zero info, or
| instructions beyond "mix this stuff with water 100:1, and
| pray"
| Arrath wrote:
| Yeah, that lines up with my experience with that crap.
| It's been a massive headache.
| Arrath wrote:
| I'm involved with a project using a form of aircrete right
| now, and we're having a right hell of a time with proper
| curing and temperatures (to be fair some of that is due to an
| outrageous spec), as well as mixer truck dwell times, and
| even input aggregate temperatures. E.G. we had to bring in a
| refrigerated semi-trailer to store the sand to ensure it was
| cool enough to make the mix during this heat wave.
|
| We are, in fact, trying to convince the owner to let us put
| in geofoam in place of the specified aircrete.
|
| It's much, much easier to bring in a trailer of geofoam
| blocks, place and size them then compared to pouring a lift
| of concrete and ensuring proper aeration, vibration,
| temperatures, etc.
| BugsJustFindMe wrote:
| If you're not making your own geofoam on site, it seems
| like the fair comparison should be bringing in a trailer of
| aircrete blocks made elsewhere in controlled conditions
| instead of being made to mix it yourself. Any idea why
| nobody makes them?
| Arrath wrote:
| A quick google turns up a handful of suppliers, so some
| outfits do make them. May not be available for all use
| cases, though.
|
| https://tarmac.com/products/blocks/aircrete-
| blocks/#all?pl1_...
| captainmuon wrote:
| Styrofoam dissolves in gasoline (in the anarchist's cookbook this
| was a recipie to make "napalm"). I wonder if this opens up a new
| venue for terrorism: drill a hole and pour in some solvent or
| catalyst, watch as the hill collapses...
| mometsi wrote:
| Sounds like some sort of reverse psychology trick by
| Halliburton.
|
| "Oh, I certainly hope no _terrorists_ come, and pump oil
| directly under our facilities! "
|
| "Yes, that would truly be a _devastating blow_! "
|
| "We can only hope that no hostile actors from oil-rich nations
| learn about our _critical vulnerability_ to this _clever_ ,
| _effective_ tactic! "
| JackFr wrote:
| The article seems to describe what I've always known as
| styrofoam, and yet the styrofoam I know that appliances come
| packed in does not have the compressive strength to support cars
| on a highway. What am I missing?
| markvdb wrote:
| There are different compressive strength levels available in
| expanded polystyrene. The stuff under our foundation for
| example has a compressive strength of 150 kPa. That's over 15
| t/m2 (>3000 pounds/sqft in medieval units).
| Arrath wrote:
| They're not running traffic directly on a road surface of
| styrofoam. A picture in the article shows a road embankment
| under construction, with a rebar mat on top of the geofoam
| blocks. This will have a concrete pad poured on it, which
| spreads the load of the road and traffic across the entire area
| of the embankment vs just point loading of the tires of the
| vehicles, so it can easily handle the weight.
| bawana wrote:
| I wonder what happens to the contaminant styrene monomer? I guess
| it's just another poison we're throwing into the water.
| madeofpalk wrote:
| > The other outcome of this streamlined construction process is a
| reduction in labor. This reduction in labor costs is a boon for
| investors and project managers, but a loss for the workers that
| would otherwise be employed for more varied labor over a longer
| period of time.
|
| I struggle to understand this. Do people who hold this point of
| view wish we got rid of cars and instead manually carried
| materials everywhere? Should we ditch earthmoving equipment in
| favor of shovels? After all, that would employ more people for
| longer.
| nerdponx wrote:
| I got a kick out of that one too.
|
| This is an instance of the "broken window fallacy". To
| understand the nature of this fallacy, I highly recommend
| _Economics in One Lesson_ by Henry Hazlitt [0]. It 's short and
| easy to read.
|
| However, Hazlitt's lesson is not the complete story. The
| question that Hazlitt does _not_ answer is, what is "the long
| run", and how exactly do the gains from productivity get
| distributed to "everyone"? This is likely where a lot of
| leftists would object to Hazlitt, arguing that it's better to
| protect current jobs than to let capitalists (or whoever) suck
| up all the gains for themselves and never redistribute them.
| You can argue about the semantics of whether it's possible to
| "hoard" wealth, but ultimately there _is_ some merit to that
| argument. But the fallacy remains the fallacy, even if wealth
| redistribution is an unsolved problem.
|
| [0]:
| http://leeconomics.com/Literature/Henry%20Hazlitt%20Economic...
| grumblenum wrote:
| I was really curious about bearing capacity of this material, and
| I found this spec sheet:
| https://my.civil.utah.edu/~bartlett/Geofoam/EPS%20Geofoam%20...
| The compressive strength is actually pretty good if you use the
| high-end stuff. I would be skeptical of the cost-benefit versus
| other common fills.
|
| I almost spit out my coffee when I saw the section on levees and
| the anchors "(if necessary)" annotation. I would be very
| reluctant to market an extremely low-density product as a barrier
| for flood protection applications. It really makes me wonder
| about the rest of the statements in the brochure.
| Someone wrote:
| That 'if necessary' probably proves to be true most of the
| time, but I think the use case they mention (levees built on
| compressible alluvial soils) can easily make it the better
| choice.
|
| For levees, there's also the even lighter
| https://en.wikipedia.org/wiki/Inflatable_rubber_dam (but those
| do have to be grounded)
| goodpoint wrote:
| "Geofoam is not biodegradable"
|
| Potential toxicity of polystyrene microplastic particles
| https://www.nature.com/articles/s41598-020-64464-9
|
| "Polystyrene is ubiquitous within sea-surface samples collected
| from across the globe" https://pubs.acs.org/doi/10.1021/es504525u
|
| Am I missing something?
| drewcoo wrote:
| If it were biodegradable, geofoam hills would turn into
| geofoam-vacant sinkholes.
| harry-wood wrote:
| The bit about petroleum solvents, makes me wonder about
| sinkholes. "causes it to dissolve and break down into a non-
| load-bearing sludge", so if some joker tips a bottle of that
| in the park then a sludgy hole in the ground will start
| forming?
| goodpoint wrote:
| Many substances are selectively biodegradable i.e. remain
| shelf-stable forever as long as they are not exposed to
| oxygen or sunlight or whatnot.
|
| Also, concrete degrades by itself. In decades it crumbles,
| pulverizes and goes back into being soil.
|
| But, importantly, it does not become toxic particulate like
| plastic.
|
| [edit: corrected phrasing, thanks zdragnar]
|
| Same for other sustainable materials like compacted soil,
| gravel, sand...
| zdragnar wrote:
| Isn't that simply weathering?
|
| Biodegradable would seem to imply to me that bacteria and
| fungi feast on it and convert it to what we consider soil.
| devonkim wrote:
| The production of concrete is responsible for a ton of
| pollution in the world and while there's significantly
| lower environmental impact concrete available, few projects
| use them because of its higher costs for primarily
| environmental benefits. The distribution of the lifecycle
| of the environmental impact matters and if things are
| pretty bad now I'd strongly consider anything with
| backloaded environmental costs over ones that have
| environmental costs incurred up-front.
| andyjohnson0 wrote:
| Its inert, so its not biodegradable, but it also doesn't break
| down the way that styrofoam* does. And it can be re-used. I'm
| not convinced that any of this makes it A Good Thing tbh, but
| it is possibly less bad than some of the alternatives.
|
| * which is an absolute menace in my opinion
|
| Edit: s/expanded polystyrene/styrofoam
| istjohn wrote:
| Geofoam _is_ expanded polystyrene.
| falcolas wrote:
| Um, this _is_ expanded polystyrene, just with a fancy
| "polite" name. Per TFA:
|
| Despite its uncanny appearance, geofoam is incredibly
| prosaic. Essentially, it's polystyrene. Expanded polystyrene
| (EPS) geofoam -- the most common type -- is made from small
| polystyrene resin beads that contain microscopic cells filled
| with a blowing agent, which expand when exposed to steam
| under controlled pressure and are molded and fused into a
| brick shape.
| tpm wrote:
| "Biodegradable essentially means that an item can be broken
| down into increasingly smaller pieces by bacteria, fungi or
| microbes to be reabsorbed by the surrounding environment,
| ideally without causing any pollution."
|
| So it degrades, but causes pollution, therefore it is not
| biodegradable. That is my understanding.
| wizzwizz4 wrote:
| > _flame retardant chemicals used to treat geofoam were shown
| to be accumulating in the ground, which led to their [i.e., the
| flame retardants'] discontinuation in Europe but not the US_
|
| It _appears_ that people are paying attention to the ecological
| impact. (In some places, at least.)
| throw0101a wrote:
| > _Am I missing something?_
|
| If the foam blocks are buried, it's less likely they'll make it
| into the water cycle. (That's not to say they won't cause other
| problems.)
|
| Also, all the samples collected are not biodegraded, but rather
| the actual molecule of plastics that's simply gotten smaller
| and smaller. See "microplastics":
|
| * https://oceanservice.noaa.gov/facts/microplastics.html
|
| * https://en.wikipedia.org/wiki/Microplastics
| 7952 wrote:
| Biodegrade means that living organisms have decomposed the
| substance. But it can still degrade in other ways.
| londons_explore wrote:
| So what happens when one of these beetles makes it into the foam?
|
| https://www.the-scientist.com/news-opinion/beetle-larvae-can...
| gabereiser wrote:
| This is pretty rad. Growing up I used to be into model trains and
| one thing that always blew me away was model train landscaping.
| You know, those amazing basement setups that recreate the Rockies
| or insanely detailed recreations of westchester subway yard. One
| of the main ingredients for building a model train layout is
| foam. Simply put, you lay foam down and then carve into it the
| landscape you wish, paint it, and then cover it with fake
| greenery. With the right setup it cured hard as rock and provides
| a foundation for the layout to sit upon. Reading this article it
| seems Sweden is making 1:1 layouts for engineering projects.
| This, to me, seems like a really great application. What I want
| to know is, how does it hold up to time, elements, curing, etc in
| the long run. Fascinating stuff though.
| blunte wrote:
| Question for you. When you want to change the landscaping, or
| say the land is sold and is going to be repurposed... what
| exactly do you do with all those blocks?
|
| And have you ever had packing material that over time had more
| and more corners rubbed/ripped off, leaving little foam balls
| stuck to every nearby surface? Now imagine that orders of
| magnitude larger scale. I hope you _really_ like little foam
| stuck to everything.
| blunte wrote:
| If there ever was an example of "f-ck you, future generations",
| it would be this.
|
| These blocks will eventually need to be disposed of, or they will
| become rubble which will "naturally" decay - and by decay I mean
| gradually have bits eroded off and scattered into the wind/water.
|
| Once they cease to be solid blocks, they become virtually
| impossible to clean/dispose.
| joshuaheard wrote:
| I bought a house with a sunken living and wanted to raise the
| floor. We used blocks of this stuff to fill up the sunken living
| room, so we only had to use 6" of concrete on top. I was
| surprised when I found out, but my builder says it is common.
|
| I don't know if I would use this stuff outdoors, though. We had a
| bean bag chair full of polystyrene balls leak outside, and I was
| finding the stuff in my yard for years.
| baybal2 wrote:
| You can equally well use foamed concrete for geoengineering.
|
| The biggest plus it doesn't turn into a chemical weapon if there
| is fire, and it can be poured right on site.
| Amin699 wrote:
| At Maggie Daley Park, one of the project's defining challenges
| was to find a material that could sit above an underground
| parking garage, which could only support a limited weight. In
| addition, the park's design brief called for "a complex landscape
| that offers experiential range" with varied character, scale, and
| seasonal attributes. To build any kind of varied topography and
| support the planned winter "ice ribbon" and play spaces, it was
| necessary to use a fill material that was lighter than soil.
| Geofoam, at approximately 1/100 the density of dirt, was the
| obvious solution.
| destitude wrote:
| They could be using glass foam which would be vastly friendlier
| to the environment.
| robbedpeter wrote:
| Geofoam is styrofoam. The "article"is an advertisement. I guess
| with all the consumables like cups and plates being wound down
| because of environmental concerns, styrofoam producers are
| scrambling to rebrand and pivot into other markets.
| MisterTea wrote:
| > Geofoam producers and boosters claim that geofoam actually
| reduces the environmental impact of a project by allowing for
| shorter construction times, reducing the need for energy-
| intensive earth moving machinery, and reducing the carbon
| footprint of the overall project.
|
| I guess they forgot about all the machinery and oil consumed by
| the manufacturing process. Granted, the oil is not being burned
| but polystyrene is not really environmentally friendly itself
| either: https://en.wikipedia.org/wiki/Polystyrene
|
| I see the economic and engineering qualities, especially when
| building whimsical parks and so on (which is a frivolous use
| case). But I can't help but feel this is a perverse way to build
| natural landscapes such as parks. Imagine what happens when a
| burrowing animal finds its way onto one of these things? What
| happens when you have to dig under the foam in the event you need
| to do so? What about tree roots? What about micro-plastics? et
| cetera.
|
| This line sums it up nicely:
|
| > It can come as a shock to realize that giant bricks of
| polystyrene are stuffed below the turf, like silicone implants
| under the skin of a city.
|
| Perfect for the Instagram generation: a fake city with fake tits.
| Cthulhu_ wrote:
| I expect the foam to collapse after just a few years, causing
| the whole hill to just deflate.
| throw0101a wrote:
| There are houses built with foam blocks as the form for
| holding concrete (ICF) built in the 1970s that are still
| standing.
|
| Make sure the foam used has the proper PSI rating, and make
| sure you have proper drainage to reduce hydrostatic pressure,
| and there's no reason these things can't last 'forever'. It's
| not like the foam is biodegradable after all.
| klyrs wrote:
| Not biodegradable, no, but it does have this pesky
| vulnerability to gasoline and other solvents, which turn it
| into napalm. Thanks to the extremely low density, a little
| bit of liquid can dissolve a whole bunch of foam. So long
| as it's well-sealed, there's no problem, but I'm a little
| nervous when I see it being used to construct highway
| onramps and the like.
| PLenz wrote:
| Nothing new under the sun. Take a look at Central Park in New
| York. Almost everything you is is constructed. They dug the
| ponds and built up the hills. They didn't have geofoam but if
| they did they would have used it. Look a Tunnel View in
| Yosemite. It's there because NPS manages the trees below the
| view to frame it. Hell, the very idea that there is urban space
| and nature space is something we humans invented.
| nerdponx wrote:
| For what it's worth, I don't think there's anything wrong
| with creating (or re-creating) natural spaces. There's no
| reason to become a nihilist over it.
| rosetremiere wrote:
| I think you're not replying to the main (or at least, most
| important imo) point of the parent: it's that this man-made
| landscape has now plastic embedded in it, with all the
| potential risks it entails
| aeoleonn wrote:
| I think it's disgusting that polystyrene is legal at all. It
| contains toxic chemicals, and in any other context outside of
| construction it is considered trash-- pollution. And in
| construction it becomes trash once torn down. It is outlawed in
| Europe as a single use plastic. And it should be in the US and
| rest of the world in any application due to its risk of becoming
| a toxic, persistent environmental hazard.
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(page generated 2021-07-29 23:01 UTC)