That is pretty cool. I have no engineering thoughts on this, so can't comment on how far you could go etc.I think it looks quite cool though, and the whole thing opens up lots of ideas in my mind.I can't help but wonder how much the nails play a part in this. Kind of like little rebars for reinforcement.I think you should make some cool legs for this and use it in your garden.
Cindy

Great experiment Laura! How did you test the weight you could put on it? I would test further just to see what will break it just like you suggested.

I love styrofoam and use it alot in my sculptures. There are all kinds of commercial use styrofoams out there. I have collected lots of pieces from construction sites. This is not blue board stuff. This is really hard, dense foam that is used alot to remodel strip centers. Also on new construction of strip centers. It comes in wonderful architectural designs. Once in place, it is sprayed with a concrete mix to look like detailed cast concrete or stucco. This stuff is hard enough to sit on without concrete! But, it cuts like butter. I cover it with lath, attached with floral pins, and then cover that with concrete mix. Doesnt take much mix so the finished sculpture is pretty lightweight. I havent made furniture, but a bench would be a great project. By adding the lath like I do, I think that even if the piece broke...it would not just break into two pieces. It would crack and pull but the lath would hold it all together enough so that the poor soul sitting there could get off before hitting the ground! - Carol

Carol, your information is so exciting! What do you mean by "used on new construction of strip centers"? I am thinking you mean shopping malls; is that correct? Could you give me a name for this kind of foam so I could search online for more info? I will drive around town tomorrow looking for likely construction sites! Thanks!
Laura

IMO this is an extremely dangerous bench design and should not be promoted.
There is nothing preventing a person sitting on it crashing to the ground when it breaks.

This is not a bench design - this is an experimental slab to test the strength of the materials. Please notice that my first photo is titled :
" styrofoam benchtop-a test, not a design"
Laura

Laura writes
This is not a bench design

I'm very happy to see you post this. As you read in the responses some are reccomending you put this in your yard as a bench. That would be very dangerous.
I have seen a few dangerous practices posted here and picked up by excited newbies as great ideas.
There was a tufa retaining wall being promoted here for months that was very capable of causing serious injury and even death and there was not a single critical word posted.

It is great to experiment but when we go public in a group full of newbies we have to be careful that they understand it's only an experiment and not a finished practical piece.

A bench collapse in a yard filled with concrete and stones could seriously hurt a child or and older person.

I kept filling tubs of water on top of the bench slab. At 50 gal I ran out of tubs. This is 417 pounds. The bench was perfectly solid, no change in the styrofoam/concrete/mesh slab. 30 minutes later I looked again and it was still perfect. I had to leave for 3 hours. When I returned I took a photo of the bench. (see photo below). Obviously, during the 3 hours the slab began to sag. Now it is an hour later and the sag seems no worse. I'm going to leave it like it is for awhile to see if the slab ever breaks, sags more, or whatever.
So far, it seems that the weight limit of the slab I made over 1 & 1/2 inch styrofoam is less than 417 pounds but not much less. Pretty impressive to me! Even if the sitter weighs 417 pounds, it won't be a fast fall to the ground!

Here is a link that might be useful: new photo of sagging bench here

Hi Laura
You stuccoed a piece of styrofoam and laid it down as a bench. With nothing in the structure to protect it from collapsing.
When it fails, the victim will go crashing to the ground between chunks of concrete and stucco.
A fractured elbow would be the least of their worries.
PLEASE contact Quikrete and discuss this with them. When I did just that the rep I spoke to almost fainted.:)
He came very close to telling me I was crazy and suggested I not use their products at all if I was going to use them in such a callous fashion.:)

While I find your test results quite amazing and have no idea why it is carrying that amount of weight...I have to agree with Tufaenough that it definitely needs a big "DO NOT ATTEMPT THIS AT HOME" sticker on it.

Neither the blue styro nor the QuikWall were designed to carry any tensional or torsional loading. And with no rebar or lath to at least tranfer or spread out some of the load, this project is a real head-scratcher. I doubt the guys on "Mythbusters" could have pulled this one off without wrecking something. Is a puzzlement. But, one worth testing further...with lots & lots of caution. 500 pounds of water falling over could do some damage. Keep us posted.

It is amazing.:) I suspect the support is coming from the fiberglass cloth under the styrofoam acting much like a hammock. But as the materials harden and cure that ability will be lost and the cloth will break or tear.

Tango - it is 50 gallons of water, not 500. I just took it all down because the sag hadn't gotten any worse in 6 hours and I decided to save the slab and add another layer of mesh and concrete and retest in a week. That wouldn't really prove anything about 3 layers though - it would just be a test of repairing a saggy 2 layer slab with an extra layer. So - instead - maybe tomorrow I will just stack all the tubs back up and refill them and add more til the slab actually gives way. I would be interested to see what happens when it actually fails instead of sags. (to me "failing" would be giving way enough so that the tubs of water on top fell to the ground. 417 pounds couldn't do it so maybe if I put 500 pounds on top it will fail?????)

Laura,

What a cool experiment! Where do you get your EIFS mesh? Slap some legs on and call it a bench...just post a "no wide loads" sign on it :) I like hearing about new materials...maybe you can look into slapping a piece of wire lath in there instead of the foam.

Keep up the cool experiments.
Justin

I found the mesh at a local drywall supply business for contractors. A roll 150 feet long and 38 inches wide cost 85 $. I think people have found it for less online.
I hope others try it; I would love to hear more ideas what to do with the mesh.
Laura

Laura, congratulation on your free spirit and quick thinking. People, even "experts" use to believe many "facts", without proving it. Then somebody starts thinking "why", "how", "when" ....and new ideas born!

Andrea

Andrea, Justin.... thanks for the encouragement. I think trying to find those "how", "why" answers is the thrill of all this for me. I don't seem to run out of questions!
Laura

Wow, you better start cranking out the "benches" if you have 150 feet of that stuff. Your slab really looks like a flat hunk of rock!

Well, I better get back to the styrofoam and quickwall house I started building :)

I've seen the mesh on ebay on occasion. I think it's called fiberglass mesh or stucco mesh. Can't remember which.

Tufaenough -- lighten up. Geez, it was just a test. I don't think Laura knows or has many 417 lb. people visiting and if there's a danger of someone large sitting on such a bench, once she makes one, she can just put pots of flowers on it in advance and use it as a display. You noted that she had the entire load centered but she probably wanted to do that to test the load strength, as she stated. I also doubt that a child's weight would have any effect on the slab at all. I have wooden seating in my yard that probably would collapse with half the weight Laura piled on hers. Of course she could put a discrete "Load Limit xxx lbs. Sit at your own peril." sign on it as a warning.

"I can't imagine that material support a 100 pound person.
It's stucco not concrete."
The above line is a direct quote from a Quikrete representitive.
The implication of the bending bench means none of the strength is coming from the concrete material.
It's basically a hammock made from fiberglass cloth.
Once the materials cure the fiberglass will lose that ability.
As Tango said this is not something anyone should try to duplicate at home. It's extremely dangerous. A concrete bench colapsing is a far more serious even then a simple chair. The material is very unforgiving. This is why benches, even small ones weigh hundreds of pounds.

You guys just can't take it that women have more talent, wit, brain and guts than the whole bunch of you!! Chill out!

Laura-

Keep experimenting! Your bench idea sounds like something I'll be giving a try this winter (one can never have too much seating) with components that are separate and can be mixed and matched. It would be great to have seating with a stone "look" that could be moved around the place as different needs arose.

I applaud your moxie and patience in the experimentation department. You have to test your piece to failure in all of it's configurations (including leaving a piece out all winter, then checking it in the spring for deterioration/weakening.) For my own tastes, the supports wouldn't be on the ends of the bench, but scooched in a bit from the ends, so that the load-bearing aspect would be mitigated somewhat. I'll make "making a bench" my targeted winter project.

I look forward to seeing the progress you make. You go, girl!

MMW

I still think the design is great and that you should put some legs on it and use it in your garden......It would look great with some hypertufa pots and plants, or grots, or a tufa geko etc.sitting on it. I have a number of benchs in my yard that aren't necessariy in the best spot to sit on, but they look great there, or that I have little figures on and they are more of a decorative look. This piece could be used for any number of decorative uses. I think your experiment is great and very thought provoking. It seems that almost every one understood that this was an experiment and not more than that. Don't let any one's critisism slow you down from having fun and experimenting more. This forum has always been about sharing ideas and thoughts, it never used to have the critical tone it has developed. Keep playing in the mud girl !!
Cindy

Laura, That's quite an experiment you got going there. While I, myself, wouldn't use that as designed as a bench for people, it has some potential. I like the idea of a foam core to lighten up the weight.

As I was reading this thread and thinking about it, I had an idea to strengthen it greatly and still keep the weight down. If I were to use some 1 1/2" angle iron (not aluminum) to make it rigid without too much weight or cost. I'd use 3 pieces of angle iron. One each on the front and back edge and one in the middle. I'd cut the stryofoam in half lengthwise and put a piece of angle iron in the center too. I'll use construction adhesive to keep it all together. Then as you did, use some mesh on the top to help keep the 1st layer together. Then do the finish layer as anything that'll look good.

I think that'll work for me to help keep that span more rigid and safer. Great idea starter Laura, thanks again.

Laura,

I wonder where we'd be without experimentation? Maybe still making things with rock tools! Nice work!

Deb, of the incredibly dangerous and possibly lethal knee-high hypertufa block wall

What a smile this puts on my face ..........I can hear the roaring - soon in numbers too big to ignore! I love it when folks, regardless of gender, are mindfully experimental. This is so kewl - what fun!

I need to make a "cover" for my new well head. A couple years ago, I fashioned a hypertufa boulder .....however, even that would be too heavy for what I have in mind ....... so this provides some fodder. First, though, to get the mesh cloth.

Lest anyone get too concerned, no one will be sitting on the well head cover - OK? If a concrete representative wants to pay me a home visit though, I would welcome any free samples he/she might bring.

Kudos to those who are brave enough to think outside of the box!!!!!! Orville and Wilbur may have never taken such foolish risks if they listened to the naysayers - right?

I love the idea of a display area - if one was to use the slab as shown - and/or shoring up underneath w/ more of the concrete supports - but I understood from the very beginning that this was an experiment!!!!! THANKS!

grins

Vicki

MuddyMesaWoman. You said,

" I'll be giving a try this winter (one can never have too much seating) with components that are separate and can be mixed and matched. It would be great to have seating with a stone "look" that could be moved around the place as different needs arose."

What a great idea-starter. Mix and match components of lightweight, moveable stone sound super. I sure hope you start a thread on this topic when you have details to share!
Laura

Ditto to all the positive comments about your EXPERIMENT.Of course you won't use it for sitting until you've proven its strength in that regard.That would be foolhardy!
I like the reinforcement suggestions.Some weight gain,but far greater would be the strength of the piece.
Keep up the EXPERIMENTING.That's how we learn.
Cheers from here

Laure, looks like FINALLY everybody understands what you wrote at the beginning, that it is not a bench, it is an experiment. It was clear and loud!

Today I decided to break the benchtop just to see how it would break. I flipped it over so the sag from yesterday was on the top. I put 180 pounds on it - no sag. 350 pounds.... no sag. I gave up all pretense of being scientific and let my 180 pound friend jump up and down on it trying to get the slab to either break or sag to the ground (7 inches). He finally had to leap out of a lawn chair onto the thing to make it really fail. (He seemed to be having a great time and suffered no injuries! )
The concrete cracked in some places and the styrofoam split a little. I had to pull off a little of the mesh to see the crack. I have added a very poor photo to the album. I just took it with flash in the absolute dark. I couldn't see what I was doing. Ignore the white broom handle (how did that get there?)... ignore the distracting fact that the thing is sitting on a sidewalk about the same color as it is.... ignore the rest of the problems. You might be able to get a glimpse of the blue crack. I don't know what I learned from this but it is interesting enough to me to start over and make a new one with either thicker concrete, or a third layer of mesh just to see if that makes it able to perform better in the weight limit test. I will put the quickwall layer on the outside this time since it is waterproof.
For anyone who wonders.... here is how I put the mesh on the styrofoam:
If the styro was 17 by 44, I cut 2 pieces of mesh 17 by 44. I cut lots of strips of mesh 8 by 8. The 17 by 44 piece went on top with concrete and the 8 by 8 pieces lapped 3 inches onto the top piece, over the edge, and around to the back side. When that dried 12 hours I flipped the whole thing and applied the other 17 by 44 inch piece to the back. I waited a day or so and repeated this process to make the second coat of mesh/concrete. I pushed roofing nails into it to keep the mesh concrete layers from falling off the styro when I turned it.

Here is a link that might be useful: see photo here

HAHAHAHAHA! Well that settles it...if it doesn't pass the 180lb man jump test...it aint concrete :) I would have really liked to see that. Did I miss it, or did you mention how long you let it cure before you started abusing it?

Way to go!
Justin

Pssst...
If the Quikrete representative is going to faint over it, they won't sell more Quikrete to you!!

Andrea

ROFLMAO Thanks for the experiment. I can just see your neighbors calling you and saying, "Uh, Laura, your stone benches just blew into my yard again!" Only concern I had during your experiment was those darn roofing nails. What if the bench broke and your buddy got a nail in the foot. Then at the hospital, the Dr. asks, "Now could you please tell me AGAIN, HOW did you get that nail in your foot????" Thanks for the bit of entertainment, and the inspiration! It was getting a little dry here at the HT forum!! BB

Justin, your question about how long I let the slab cure before I started my "testing" is an interesting point. These thin layers of concrete look "set" within a few hours. I had to flip the piece after it dried on one side before I could do another side so that was 4 work sessions. I got the whole thing made in 3 days I think. After that I waited maybe 3 days before I gently sat on it and thought "hey, this may work". I let it "cure" a few more days. I remember thinking I'd waited long enough when it was 7 days from the last work session (wet concrete). So...... I guess it cured about 7 days. I wonder if it would have done much better if I had left it alone for 30 days before the jumping started?????????

Another fact that interests me is that, in the test where I piled on 417 pounds of water and the slab didn't change - then waited 30 min and no change - then left for 3 hours and came home to a slight sag..... Before I left, I tried to shift the top water tub a little and that started the water in all the tubs sort of jostling around and leaking out a little. Water was running down onto the slab in just one place at the rate of a couple of cups at first then a little drip, drip, drip. When I came home 3 hours later the water seemed to have soaked into one section of the slab and discolored the concrete. My thought was - "hey, it's concrete - water didn't hurt it". However, now that I think about your question about curing and I think about the fact that the wet area is exactly where the sag started and was the place the slab finally failed............. I wonder even more about how the test results would have changed if I had let the slab cure 30 days.
Laura

Time for some sympathy for tufaenough - was it Fonzie who said "sit on it",'scuse :), Vilify the message maybe, not the messenger you guys.

I have found both the technical and the social aspects of this experiment to be absolutely fascinating and I'm genuinely looking forward to following the next round of tests. It's things like this that make life enjoyable and at the same time, lend support to the argument that maybe humankind really is interesting enough to warrant abduction and study by extraterrstrials after all. Cheers to all.

Laura, I am interested in one more test. How strong is the styrofoam board without the concrete?

Andrea

Tango-can we be sure that YOU weren't just returned?
Cheers from here!!

Rick --- that was a long time ago. Besides...Project VISIT is no more.

Andrea, I just went outside to test the styrofoam by itself. I used a piece of the blue stuff the same thickness and the same length as my benchtop but only half as wide so I know it wasn't exactly a "fair" comparison. However, I don't think it made any important difference because it sagged when I put the empty 5 gal bucket on it and broke with a loud snap when the bucket got 2 and 1/2 gal of water in it. That would be about 20 pounds. Pretty far off from the 417 pounds the benchtop held.
Laura

Thanks Laura! Your experiment and the result is really remarkable.

Andrea

Laura, thanks for the info on curing. I'm not sure what would happen if you let it cure longer. I'd be willing to guess that moving it around on day one or two might have been more significant than only letting it cure for a week. It is interesting that it failed where the water was. If you're going to repeat this, I'd suggest doing several little ones, with each variation on a separate piece. Then you can compare your different variables to something. Of course, it's easy for me to suggest something for you to do :)

I sure hope I don't have to put my projects through so much torture before I'm willing to put it in my yard. Then again, I can see myself being grilled in court, "you mean you didn't try the 180 lb man jump test?"

Looks like a good material to try with my next big project.

Laura, you might like to buy 'cool room panel', a commonly available building material for making cool rooms consisting of polystyrene foam sandwitched between two thin sheets of powdercoated steel. It is amazing strong because the steel provides the tensile strength and foam provides the stiffness. If you took this, cut it to the right shape and rendered over it you'd be able to make a strong bench in no time.

The other danger is that these are 'truss' structures, which tend to have catastrophic failure rather than breaking gently. This is true of practically anything you make using cement though, so I wouldn't worry too much.

Here is a link that might be useful: coolroom panels

I love the great input people have on this forum! It all really serves to push a person's imagination and creativity.
Nathan, thank you for this new information! I will go check it out.
Laura

Laura

I think this method would be great for table tops too. Strong and light weight. Of course if you serve "heavy" meals, all bets are off.

Loved following the link on the coolroom panels - from that wonderful land down under to a USA site that is within spitting distance !!!
I will look forward to further commentary here on the subject - hoping some other tinkering will happen .......this is such fun!!!!!!

Vicki

I don't really understand the foam part of this. Is the foam used as stength or is it also used as a mold. and where do you get that styrofoam.

Hey Laura. Don't let the naysayers discourage you. You can imagine what they said to folks building ships out of steel........ - Mike

Clairdo2

As I understand it, Laura uses foam found at building supply places, the kind used for insulation. It comes in large sheets, maybe 4'X 8' and possibly in various thicknesses. It may seem sort of pricy at first but I think one could get a number of projects out of one sheet.

Laura uses it to reduce the overall weight of her bench top and still give a substantial "look". If you live in an area with a lot of commercial construction going on, you might find scraps in a dumpster. I, unfortunately, live in the boonies so don't have that option.

Thanks Fleur! I forgot to answer Clairdo2. Sorry, Clairdo.

I am hoping someone has more information or some experience using the coolroom panels that Nathan Hurst wrote about. If that product can be cut easily with common tools and isn't too expensive, it sure sounds interesting.
Laura