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Old 10-08-16, 06:01 PM   #1
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Default EPS crete (DIY insulation infused concrete)

First off my camera is down, so no pics.
We first started reading about EPS crete about 5 years ago, it is fairly common in Europe, in NA not quite so much.
Here is how we do it.
We collect styrofoam insulation, there are several sources, hot tub cover makers, SIP's makers and roofing contractors tear offs etc.
I built a little machine, basically a plywood disk bolted to a pulley with drywall screws sticking through, you can google other designs, mine worked for me with what I had on hand. We feed the styrofoam against the sharp points of the screws which grinds the stuff into crumbs. Depending on your application thumbnail size and smaller seems to be good.
We mix it in a cement mixer at a ratio of 1 cement, 2 sand, and from 5 to 10 eps grindings by volume. There are reports of people using 50 parts of eps and latex glue or paint as a binder, we don't push that envelope.
We start the mix by adding sand, water, and cement, we add 1/2 a cap of basf 30 superplasticizer to help the cement paste to disburse. Some add a little detergent, we found it of no value. Then we add the styrofoam until the eps is grey with cement paste, no white showing. We want no liquid paste in the bottom of the mix, the plasticizer helps with this. If you have liquid, just add another bucket of eps. or a little cement powder and sand.
With the mix ratio we use there is lots of room for adjustment.
Ours usually pours out of the mixer, you may have to help it come out.
To place the epscrete tip it into the cavity or space where you want it, and tamp it down, I use a hoe, or screw a piece of plywood on the bottom of a 2X2. Pat it down well so that it does not want to separate, if you have excess water the styrofoam will float up, that is not ideal.
I believe California rates eps crete at r2 per inch.
It is a fantastic substance takes about 3 days to gain much strength, you can walk on it
I am guessing that we attain 100 PSI strengths easily.
We have made blocks and stacked them driving rebar down to hold them, using them as insulated forms for foundation walls, we have used it as filler
between berm and foundation walls, as tiles which we can walk on, though they get crumbly with traffic. and have used it to ensure no air pockets under our flat roof plywood skin.
Wont burn, insect proof, some structural strength, some insulation, about as eco friendly as you. can get using cement, and quite inexpensive.
I will try and answer questions as they arise, & it will take a bit of trial and error to get it working the way you want.

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