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nibs 10-08-16 06:01 PM

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.

philb 10-10-16 11:09 PM

Hi Nibs,
EPSCrete is good stuff. I am currently building a shipping container house and insulating on the outside with basically the same recipe you are using. I do add flyash, fiber and "poly" to the mix. Poly is EVA (ethylene vinyl acetate). It's the plastic layer on smartphones and solar panels, just to name a few.

Fly ash makes a harder tougher end product. It also improves non-flammability.
Poly gets the eps beads to adhere better to themselves and "glues" to wood or steel substrates. Latex, Tite Bond Two and Elmer's wood glue are in the ballpark to what poly will do. I mix all additives with the portland in powdered form up to several weeks in advance. On pour day, I add sand, water, eps beads and the 5 gallon bucket of Portland powder mix. It's much easier and more accurate that way.

One ounce of polypropylene fiber goes into 6 cubic feet of product on all my mixes eps or concrete. It keeps it from cracking and improves the shock loads.

The house eps walls are one foot thick. The roof's slope is 1/2" per foot so it varies in thickness from 2 feet to one foot. Why so thick? I get a 24 foot Uhaul crammed full of clean eps every month. Also, in tornado and hurricane prone areas, epsCrete will absorb energy from flying objects.

A half inch layer of stucco covers the epscrete walls and half inch of ferrocement covers the roof.

I estimated the R value very conservatively at 2 also. There is a linear relationship between the amount of portland/sand and eps. You can graph it and get close.

I have a few bad videos on YouTube that illustrates it's non-flammability. The worst golf ball sized sample would burn with a propane torch flame directly on the sample and self extinguish once the torch was removed. The best would simply glow red. Oxygen and acetylene would probably reduce it to cinders.

Epscrete will absorb water and retain it throughout a hot summer so water reducers are important if it is poured in thick layers like one foot thick walls.

I still need to do more psi, break, crush and mutilate tests.

If there's an interest in epscrete, I'll dig up photos from G+. also has several large posts on this topic.

nibs 10-11-16 02:02 PM

I have used fly ash in quite a lot of my work, it works really well, ups the strength or replaces some of the cement.
Put a brick of EPS crete into the firebox of my hot tub heater, after a couple of days the styrofoam was gone and had left an interesting cement sponge looking brick, still fairly strong tho'.
One of the neat things about epscrete is that it is light, so forming can be much less work and money.

AC_Hacker 10-16-16 09:50 AM


Originally Posted by philb (Post 52025)
Hi Nibs,
EPSCrete is good stuff. I am currently building a shipping container house and insulating on the outside with basically the same recipe you are using. I do add flyash, fiber and "poly" to the mix. Poly is EVA (ethylene vinyl acetate). It's the plastic layer on smartphones and solar panels, just to name a few.

How about photos of your project?


philb 10-21-16 09:56 AM

1 Attachment(s)
Sorry, I didn't see your request.

Heres a photo of the roof.
The area to the left of the wheelbarrow shows the 6 inch tall strap iron and braces that strengthen in the roof. Over that, I pour a load of eps onto the shipping container's roof. After several 6 inch pours and drying times, I cover the eps with a 3/4 inch layer of polymer modified mortar. I consider the mortar to be waterproof but still add a layer of latex paint that soaks into and bonds with the mortar.
I'm pouring every available day in an attempt to complete the roof before the snow starts flying. Only have 20 out of 55 yards to go!

philb 10-21-16 10:23 AM

1 Attachment(s)
The mixing operation.
Polymer modified portland and sand are added to the mixer from 5 gallon buckets and mixed with eps from the large white bag hanging above the mixer.
The lift is made from Superstrut steel from a local big box store. The structure is only lifting about 120 pounds. Last spring I forgot to lower the bag out of the air at the end of the day. A storm came in with sustained winds of 42 mph with gusts of 60. That bag was less than 1/4 full. I just knew I'd find everything on the ground. The next morning I found the bag and structure intact and unmoved. I did test the deflection, weight and did a bit of math before final construction. Gotta learn to trust my math and testing more.

nibs 10-23-16 04:10 PM

I always try to do my epscrete either in a sheltered location, or on a windless day,
I find it pretty hard to stop the stuff blowing around.
Some people wet the eps in the bag with a little liquid detergent to help wetting.

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