Styrofoam Concrete

There are many concrete projects, such as benches for sitting and walkway fill, that can be made using light-weight Styrofoam Concrete.  By substituting Styrofoam trash for store-bought gravel in the concrete mix, one saves on not only weight, but also on the cost of materials.  

To the best of my knowledge, Styrofoam is not a popular material for plastic recyclers.  Recycling it at home eliminates transportation costs for this bulky and low-value material. 

Many people don't own the property where they live, so maybe the incentive to build a castle for the owner over time is not there.  Instead of filling our dumps with this stuff, we could be building cities out of it, if we were motivated enough. 

I live on an island, and our dumps are filling up fast.  Taking waste and finding constructive uses for it is the best way to gracefully live with all the trash we generate. 

Styrofoam concrete probably has good thermal insulation, compared to rock concrete.  It might be a useful construction material in both hot and cold climates. 

Step 1 An early experiment

This is a porous block of Styrofoam and cement.   By filing blocks of Styrofoam with special tool I made using lots of roofing tacks, I was able to make a supply of pea size particles. 

Using a soupy cement and water mix, I got the particles wet with the minimum amount of the mix needed to keep them stuck together.  By using the minimum amount of cement, the air space between the particles is not completely filled and the block is porous.  The block is fairly light weight.  It's strength is not what solid concrete would be, but sometimes the light mix is just fine for the job. 

I don't know what kind of uses this combination might have, but its porosity is interesting.  Perhaps, it could be a filter for air or water. 

Comments

[tonygoffe]

Hi, tony in Jamaica... you could also attach wire mesh with staples and render that with cement... THAT would give you a steel componenet and more structural strength...You would want to use big syrofoam blocks, tho....

[hardlec]

Have you considered putting medium sized chunks of foam in your concrete mixer with some sharp gravel to see if that might reduce the size of the chunks and may make them a more uniform size? I used a similar technique doing lapidary work with a rock tumbler. I'm also very interested on using concrete as a skim coat on a foam armature. Good stuff

[mbelfatto]

A mulcher mower with bag would work great to break the styrofoam up smaller.

[Thinkenstein]

No, I haven't tried that tumbling technique. I imagine running the mixer like that would consume a lot of energy for the amount of foam modification it would accomplish. I think the claw shaft and comb grate is probably the most energy efficient way of breaking it up. I don't know what you mean by a "skim coat" on a foam armature? Is that for sculpture? What is the skim coat for?

[hardlec]

Sculpture, yes. Light weight is a real virtue even for lawn ornaments. Acetone, AKA fingernail polish remover, works really well dissolving Styrofoam and beaded foam. I've never considered using foam as a core I could dissolve out later.

[xarlock667]

IN metal casting we use styrofoam and concrete as an insulator in the outer layers of our refractory coat. The foam vaporizes leaving the concrete full of hollow insulating pockets. In our case the simple heat of the fire is enough to get rid of the foam itself, using something like acetone may dissolve the lime in the 'crete and degrade it's strength. Try heat exposure from a heat gun or something. The concrete itself WILL NOT burn for the first thousand+ degrees so just be careful to not burn the surrounding area.

[thaicares]

I have another way to make things out of packing peanuts and virtually just the packing peanuts although they are only the organic one's so this is a great way to get rid of the other packing peanuts REALLY COOL :)

[chaguin60]

THINKENSTEIN have you allready used papercrete?IVE heard that that papercrete in a tropical island like PUERTO RICO rains a lot it tends to breakdown real fast ,is it true?Anybody that has tried in that kind of weather let me know.

[Thinkenstein]

I have no experience with papercrete, nor have I heard of anybody using it here.

[themadtreky]

I love close to the beach in Florida, recently I've seen a few buildings going up that the walls are concrete over recycled Styrofoam blocks. I'm not sure exactly how they did it, but it was interesting to see the beginning of the construct and the end results are strong and look just like stucco.

[rapidprototyping]

for fibers in your concrete try hemp crete on wikipedia it willexplain the fibers thing . also the old fashioned peblo building was a series of fibers all the way to timber sized fibers

[jackoftheforest]

the materials that make up concrete do not break back down to their original state. Effectively you're encapsulating something that takes tens of thousands of years to decompose with something that will not decompose for hundreds of thousands of years. What about using Cob? Although as a fully decomposable building material, using Styrofoam would effectively pollute it.... I suppose if you don't mind never getting rid of your cement construct it's a great idea- but if you want to do anything to it- you've pretty much made THE un-recyclable material for the ages. Albiet a constructive use of styrofoam. I would be interested in the structure changes Styrofoam makes to the concrete, if it significantly lessens the integrity of the material. If not, using it for housing foundations would be a good idea- they stick around for a long time and are easily reused. Cheers!

[Pader]

Wow, What is it with you people? Before even thinking about what you are saying you jump right in with all of this politically correct rubbish. (Now that is one kind of trash that should never be recycled but unfortunately it does, again and again). However, you seem to want your cake and be able to eat it too. Is it not the aim of all responsible people to recycle rather than send to a land-fill? That aside, you are totally wrong on several other accounts too. Organic fill would not be readily prepared and would be fibrous and useless as an aggregate unless it was something like wood shavings but that would be next to impossible to get any kind of smooth finish. As to the material being unrecyclable, wrong again. If the author chose to get rid of the material, it is easily crushed and used again as an aggregate as now the styrofoam is encapsulated in the cement slurry rather than light pieces which are the real pollutants as they will be easily blown about the landscape. The real howler is your psuedo knowledge of construction. Light weight screeds have been used as floor screeds for a long time (such as Boral-Lytag which uses 'blown' particles of lightweight material as an aggregate) as they are a very good insulators, but something as light weight as this material could never be used as a foundation as it would crushed under the building weight but suitably moulded into blocks (a wooden box will do), this material could be used for internal, non-load bearing walls and it's texture would easily over-coat with a decorative finish.

[Thinkenstein]

Old nylon-cement rubble and styrofoam-concrete rubble can all be used in road fills. -- To modify old structures with these materials is easy. The nylon-cement cuts easily with a cold chisel and a knife to cut the nylon. I have never broken up an old styrofoam-concrete structure, but I imagine all the old pieces could be mixed into a new batch of styrofoam-concrete and built with somewhere. -- The idea of the Termite Nest City, might be built using these materials. In such a city, very little of old structures would ever be demolished, since city growth is always upwards and outwards. Rubble would not be an issue.

[mstar]

Many of the piers along the coast of Southern California are made of gigantic styrofoam blocks encased in rebar cages and then covered with a thick layer of cement. I also seem to remember seeing something about freeform houses being made of a styrofoam substance shot onto a chickenwire frame and then coated with cement. Apparently the styrofoam does not affect the stuctural integrity of the cement. Environmentally, styrofoam may be a pain but chewing up trees to make plywood (which is probably as toxic as styrofoam) is not much better. I doubt that I would mix styrofoam chunks with cement because gravel is cheap and easy to come by. Besides that I favor smooth surfaces and styrofoam tends to float towards the top (even in cement).

[Thinkenstein]

For me, it solves a little bit of the general recycling problem we all share by taking care of what comes to me. -- Gravel is cheap, and heavy to transport. Styrofoam trash is free. If we all sucked up what was local to us and built out of it, it could be a very sculptural material to build an interesting city out of. -- Well, I know it has some uses. I don't know its limits.

[mstar]

I've actually got no problem with your use of styrofoam. I save a lot of the stuff myself and may try using it in a similar mannner for a couple of future projects like planter boxes and other garden things. Environmental considerations aside, styrofoam is everywhere, trash bins and landfills are full of it, it degrades slowly and there is no real way to get rid of it safely. Using it as fill material for sculptural cement is a novel idea but I would reduce the size of pieces to increase the overall strength of the material. The manufacturers of styrofoam packing parts and other items commonly run their "mistakes" through mechanical chippers connected to large collection bins or baghouses. That ground up styrofoam is then combined with unexpanded styrene balls in huge molds to produce styrofoam blocks that can be cut into slabs. The steam injected into the mold expands the new material and bonds the ground up materials into a single solid piece. Essentially you are doing the same thing but using cement as a binder. The larger the pieces are that you use the less structural integrity your finished product has, and if chunks of styrofoam are close to the surface there is the possibility that the cement will wear away and expose the styrofoam beneath. To avoid this, to ensure a better finish, and to improve the workability of the slurry I would run the styrofoam through some sort of chipper or leaf shreader to make smaller pieces. You could still use large blocks and chunks to build up the basic form, but then go with a finer ground mixture for the top coat. The finer ground slurry mixture would allow you to produce works with better detail capabilities and surface texture not possible with packing peanuts and large pieces. I imagine that you could mix a lot of of ground material with your cement before you reduced the quality of the surface or the sturctural intergrity of the finished work, but you would have to do some experimenting to find a good mix. I would not be afraid to use a three to one ratio to start with, but the smaller the styrofoam pieces, the better it will bind together and that equates to better detail and surface texture. Styrofoam may be an environmental disaster but there is a lot of it around, it is still being produced and that is not likely to stop any time soon. Finding alternatives to filling landfills with the stuff is a worthy pursuit and I think your idea is a pretty good starting place in that direction.

[natman3400]

Think of it this way, your taking its toxicity out to some extent.

[Javin007]

That bench seat is fantastic! I'd LOVE to have something like that in my yard... Now I just need a yard.

[tdorsey123]

Thinkenstein, I really enjoyed your write up and it has made me think about some of my own projects. Have you checked out any of the papercrete discussions on the web? it is made using shredded paper with sand and portland. It has a hardness similar to concrete, but it is much lighter and has a very high "R" value for insulation. I just thought that you might be interested.

[Thinkenstein]

Thanks. I know a little about papercrete. It would be interesting experiment with it .

[thequara]

The "Trash Rocks" is an interesting concept. I'm all for recycling and such, since we haven't had any significant plagues or anything lately to control the ever growing polulation... Grim thought, I know, but I can't help but think, isn't his just "hiding" non-recycleable trash until somebody else decides to get rid of this concrete and finds it full of trash? Don't get me wrong, great creativity and intent, just wish people would focus on trying to influence manufacturers to stop creating so much packaging and products that cause so much waste.

[Thinkenstein]

Yes, encapsulating the trash doesn't make it go away. Best would be to not have the trash to eliminate in the first place. Given the trash, the Trash Rocks are a cosmetic solution, but they can also be useful. Just trying to make the best of it.

[Websprinter]

I have experimented with making things from plastic milk and water bottles. The easiest thing to make is chicken feeders and waterers by cutting a smooth hole between the top and the handle big enough for the chickens to comfortably put their heads in to eat or drink. I cut the hole from the back plate through the entire front so that up to 4 chickens can eat or drink a the the same time. I also cut the whole top off for water dishes for pets. The top can be a funnel or scoop. I had fun making christmas ornaments by cutting carasel shaped ponies out and decorating them with different shapes for their mane, tale, saddle etc then baking them, removing them before they stuck, cool and paint. Last experiments I did was to bake bread size bricks for future projects. I couldn't remove the darned things from my bread pans and ended up with door stops. What I learned from this was mostly the temperature you use determines the texture of the plastic. Quickly heating to 380 degrees gives you a pliable liquid that hardens like steel! I'll play with it more when I have the time.

[hiddenartist]

How did your tinkering with plastic bricks turn out?
Did you find a reasonable and not too technical way of converting milk bottles etc to plastic bricks? If so I would love to see a step by step instructable on that.
Thanks!

[Thinkenstein]

Do you think you could make a plastic mesh out of recycled plastic; something that could be plastered with cement? Nylon fishnet is my preferred material, but I lost my source for free used stuff, and new fishnet is expensive. -- I was thinking of something that could be extruded under pressure through nozzles to make a mesh pattern, perhaps on a rotating teflon-coated drum, and peeled off as it cools and hardens. It would be nice to use up shopping bags, etc. in something constructive. -- Maybe a pressure cooker could be adapted somehow?

[spark master]

If you have a local green grocery near by the bag they ship onions and carrots is sometimes mesh and not organic. it would work as lathe, and if th eperson packing out like you they can cut it just right. I have used that stuff in garden projects. sparkie

[Thinkenstein]

Thanks for the idea, Sparkie. It seems to me that I tried onion sacks years ago. The center band, where the printing is, was solid and cement didn't stick to it. The remaining small pieces of mesh aren't very useful for stretching out and covering large areas. Plus they have to be overlapped, using up more surface area. -- Melting down the plastic and extruding it into a mesh pattern on a revolving non-stick drum would make mesh of endless length, with width limited only by the width of the drum. Plus, we could recycle more of our trash plastic that way. -- It's hard to beat fishnet. New fishnet is expensive, and used fishnet is in limited supply. I've lost my source for it.

[spark master]

What you describe is what inamtes do to make a plastic shiv to kill someone, they take hard plastics melt/form them with matches and produce weapons. Nifty except for all the blood. ciao

[mstar]

That would make prison inmates true environmentalists. Not only are they recycling toxic materials that would ultimately end up in a landfill, but they are doing it in a manner that produces high concentrations of isolated toxic fumes which they breath and thereby reduce their own lifespan; and the finished product of this labor is used to further reduce the felonious population. The ingenuity and inventiveness of prison inmates has always been amazing and it is a shame that such obvious talent only surfaces when they are confined under deplorable conditions, otherwise I am having a hard time finding anything negative about this.

[spark master]

I know it is nutty, but what can I say. Do a search for Xtal radios and look for pow radios. Simple recievers can be made, that will catch and decypher plain AM with little more then wire and the right rocks. You can even build a speaker or make one using a piezo Xtal loud enough to hear w/o a head phone. (of course where do you hide the thing, cuz you make a big cone to amplify the sound), but if you gt a single ear bud you are good to go. ciao sparkie

[bobdog]

Regarding vermiculite blends, be EXTREMELY careful handling this material, especially if it is recycled (and therefore of unknown source). A major vermiculite source sold heavily asbestos-contaminated product for decades and it was NOT labeled. Newer vermiculite may have less contamination or at least be labeled. I no longer use it at all. Regarding the styrene-in-gasoline mix, I've heard of it used as a boat patch so it is indeed waterproof, bit I wouldn't recommend large areas or constant use, gasoline is also a carcinogen and you never know when some smoker is going to wander over to see what you are doing and light up...and I've had this happen to me while replacing a fuel pump, people really are that stupid. I'd go with the styro over the perlite. As an aside, a perlite mix with 1 part portland cement (only portland, not qwikrete), 2 parts perlite, 2parts crushed used firebrick and 4 parts flake sawdust (like sawmill or chainsaw sawdust, not very fine) screened to 1/2 inch or less makes a decent low fire castable refractory

[mjw56]

If you are going to use pear-lite or vermiculite as the aggregate in your concrete you need to use a concrete sealer on it first so it does not screw up the cement to water ratio. structurally i don't know how strong it is as our schools concrete canoe was made in this process and broke in half during un-molding. but it was also only 3/4" thick.

[Migs]

My company manufactures Styrofoam and concrete. There are additives you can add to the mix that promote the beads to mix more evenly. (I don't remember the names, and the names vary by country and market) As you all can imagine, until the concrete "wets" the beads, they are floating on top of the mix. (Problematic) One of the keys to a good mix is the mixer, which should be a slow pear type mixer that revolves the mix on itself (think bread dough). High speed mixers promote high shear, and this would destroy the Styrofoam beads. On a small scale this material works, but industrially speaking, there are better alternatives, including foams that are mixed with the concrete that leave large air bubbles in the mix.

[Thinkenstein]

Thanks for the info. Mixing it with a shovel on the patio is the way I usually do it, but on a windy day that gets a little out of control since the Styrofoam weighs so little. I was making a hand-cranked mixer inside a plastic 55 gallon drum once, with mixing paddles attached to the crank shaft. I figured for light-weight concrete it might work, but I never got around to trying it.

[Migs]

You might try plaster as well. If I recall, one could mix white glue with water, then pre-wet the eps (expanded poly styrene = Styrofoam) before adding it to the concrete mix. It all comes down to economics. We take in eps and add it to new block manufacture so we don't have any waste what so ever. You can also mix the eps with a solvent like Toluene and make glue. Or mix eps with styrene monomer to dissolve it and make other things. You can mix styrofoam with potting soil so it retains the moisture better. Styrofoam is a plastic that has many uses and creatively can be used for many things.

[Thinkenstein]

Potting soil using Styrofoam particles in it is one thing that I could never understand. Other than on its surface, I don't think that plastic particles in the soil can retain much water. The little white particles always seemed cosmetic to me, just to make the potting soil look more special to the customer than it really was. -- What with the Pacific gyre garbage patch and plastic entering the food chain anyway, it seems odd to dump plastic into our gardens, on top of everything else. -- I have heard of disolving Styrofoam with gasoline and using it as a roof sealer. Do you know how that holds up under UV radiation? It sounds like a poor man's sealer, with health risks using it, though.

[xarlock667]

DO NOT EVER DO THIS!!! That is not a recipe for roof sealant, that is a mixture for damned NAPALM!!! Do not coat your roof with napalm!!! I don't know who told you to do that but they CLEARLY did NOT like you!

[MacGyver1138]

That might work, though I have done similar experiements and the result is a very flammable, and very difficult to extinguish material. It also isn't very malleable, but more putty-like. It hardens almost like platic when it dries. It is still very flammable, though.

[redplanet]

The stuff in potting soil that looks like styrofoam is called perlite. It is an expanded mineral and used mainly for water retention purposes.