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ltd123_gw

44 inch span styrofoam benchtop- under 15 lbs holds over 200 lbs

ltd123
18 years ago

Will a piece of blue styrofoam 1 &1/2 inches thick make a 44 inch wide benchtop by adding nothing but fiberglass EIFS mesh and concrete with fiber?

YES. I can't believe it but this seems to be working. The longest piece of styrofoam I had was 44 inches by 17 inches so I used that. I used Quickwall (just because I had it around) for the first layer of mesh and concrete. I used regular gray portland with fiber and sand for the second layer (with a second layer of mesh). The benchtop is still less than 2 & 1/2 inches thick so you can see I added more concrete than usual (as compared to my spheres over beachballs) for each layer.

I think this is a major amazement. I will experiment more with this. Just how long a span would work? For the engineer-minded..... I have a few questions?

1. would thicker styrofoam as the core make this stronger or is the styro such a small component of the final strength that it wouldn't matter?

2. I don't want to but I feel like I should keep piling weight on this experiment til I ruin it just to see what happens. Does that sound logical?

3. This is just a slab sitting on 2 concrete blocks right now. I wonder how minimal the supports underneath could be without changing the results....

I supported it with 3 inch wide bricks at first and it seemed as strong as with the blocks. I moved the blocks out so only a couple inches of each one supported the benchtop and saw no difference.

Any and all of your thoughts will be interesting to me. I sure wish someone else would get excited about this and go try some too!!

Laura

oops - just remembered an important element if you try this. To keep it all attached to the styrofoam (it wants to fall off after it dries and you flip the bench to do the other side)... you have to use galvanized roofing nails every few inches.... so - the "ingredients" also include 50 to 100 short roofing nails.

Here is a link that might be useful: ugly photos here

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