This is an update to an earlier post I made, I finally got a chance to make a few batches using the formula and test it. The upshot of it is: DONT BOTHER, it doesnt work worth beans. It seems to take the worst properties of both materials and combine them. It combines the structural weakness of the styrofoam beads with the high thermal conductance of concrete. It also has terrible workability.
I guess thats why I couldnt find much on the internet. I made two batches of it using slightly different amounts of water and fly ash, the first batch was very "sticky" with almost no slump to it at all, I couldnt get it to flow into the forms and fill the voids correctly, when I used a orbital sander (without any sandpaper) to vibrate the forms the styrofoam segregated out of the mix at the top of the form. I had to pack it by hand into the form and even that didnt fill the voids left in it. The second batch I mixed up I increased the fly ash and the water to see if I could improve the workability, it helped a little, but the final strength of the cured mix took a nose dive. I couldnt really measure the R value but a little playing around with a electric griddle and a digital thermometer leads me to make a WAG of a R value of .5 per inch, strengthwise the first batch tested out at about 200 lbs/sq inch, the second at about 120 lbs/sq inch. I tested the strength using a weightlifting stand, iron weights and a couple of 2x4s, I kept adding iron weights to the test rig until the sample failed. The forms were made out of scrap plywood, spray painted with a gloss paint on the inside, I used Pam cooking spray as a form release agent. Sigh, it seemed like it would be such a great all-in-one building material too, the stuff would make a decent plaster, but thats it, I wouldnt ever build a wall out of it. When I looked at the numbers, it would have been a lot better to make a wall with a layer of styrofoam, then a layer of concrete, then another layer of styrofoam. I would have used the same amount of styrofoam and concrete, but the end result would have been a wall/sample that would have been a LOT stronger with a much better R value. Oh well

-- Dave (AK) (daveh@ecosse.net), June 21, 2000

Answers

I have no idea why it didnt take any of my paragraph formatting, sorry, the original way I wrote the post was a lot easier to read.

-- Dave (AK) (daveh@ecosse.net), June 21, 2000.

Dave, I missed your first post on the subject so I am not sure what you are trying to accomplish. Perhaps, if you have time you could fill me in. I may have a solution. Jerry

-- JerryR(la) (jwr98@hotmail.com), June 21, 2000.

Dave, yours is one of the blessed few posts where an idea was followed through on and the negative results posted. Your tests were thoughtful and revealing. Thanks for saving us the time and effort.

-- charles (clb@watervalley.net), June 22, 2000.

Dave made a couple of posts, at Inexpensive barn/garage using concrete with styrofoam aggregate and How to make insulating structural lightweight concrete using polystyrene beads .

Thanks for the report back, too, Dave.

-- Don Armstrong (darmst@yahoo.com.au), June 22, 2000.

Jerry: Its a follow up to a post I made about a month ago, you can look at it if you go down to the "Older Messages (by category)" and look at the construction archives, its 12th from the bottom titled "How to make insulating structural lightweight concrete using polystyrene beads"

To elaborate a little on what I think Im going to do now, its going to be somewhat labor intensive but thats okay, labor I've got, money I dont :-)

Basically what I've thought up is a combination of cast-in-place slip form and insulating concrete form techniques, Im going to take two 4x8 plywood sheets for my outer and inner forms, inside the forms there will be a 3 inch layer of extruded polystyrene board then a 6 inch airspace for the concrete, then another 3 inch layer of foam board and then finally a 2 inch airspace for more concrete, then the removable plywood outer form.
What that will give me is a panel like this:
FFFCCCCCCFFFCC (f=foam, c=concrete, each letter is an inch) I can tie the exterior concrete panel and the inner together using threaded nylon rods that go through the foam.
Another post (sorry, dont remember who just now) has also given me the idea to use a removable timber on one side inside the form to give a tongue and groove effect on a large scale to help tie each panel together, along with the rebar. Glued foam spacers would be used to keep the two foam panels apart during pouring.
Construction would go like: 1..put form/foam up 2..pour concrete, let set 3..clamp one side of form to previous panel and put foam in place 4..pour concrete.....etc. Corners would be a little tricky but do-able. I should even be able to make the outside concrete panel look nice by attaching strips of 1/2 inch square molding to the inside of plywood form to make patterns in the concrete, like giant stone blocks or whatever.
To make the upper floor I just put up a 2x4 stud wall, 24 in. on center, and rest the floor/ceiling on that, that way there are no thermal breaks through the foam insulation to the interior and I can hang drywall on the studs (for fire safety and looks).
I should be able to do just one panel at a time when I have the time and money, eventually I should have my barn done, without having to do it all at once (which I cant afford). I wish I had though of this when I was building my A frame house, it would have helped save a lot of money. (by the way, I dont recommend building an "A frame", lots of wasted interior space, I should have done a chalet style)

The above is just my copy of an already used construction technique, done on the cheap!

Any thoughts?
Thanks in advance... Dave

-- Dave (AK) (daveh@ecosse.net), June 22, 2000.

Dave, I found the previous post and so I do think I understand your intent. You ideas are good but I am not sure the technology lends itself to the do-it-yourselfer's, yet. So, if I understand your intent, it is to be able to do much of your own or all your own construction, in stages, as money allows, structurally self-supporting, and built in insulation factors in the whole project.

Ok, first I realize being in Louisiana I have access to things you may not. With that in mind, have you considered a post/beam and ferro-cement combination, while using inside and outside layer of ferro-cement and borax treated sawmill sawdust as a filler. Great insulator, and ferro-cement is so easy and quick to use. The post/beam portion would provide the load bearing strength for your second floor. With proper planning, I believe you could do a bottom layer, leaving maybe two inches of your chicken wire exposed, then when funds permitted, attach your second layer above, type top and bottom together and continue as you can.

BTW, you can also do your roof using ferro-cement, super strong using four/five wire layers.

-- JerryR(La.) (jwr98@hotmail.com), June 22, 2000.

Jerry: I've considered post and beam construction and using ferro- cement quite a bit, as a matter of fact I made the well shed using post and beam construction on top of a horizontally insulated slab on grade foundation. (the insulation is buried 6 inches below grade and extends out from the slab 4 feet to prevent frost heaves, I hope that makes sense)
I've had reservations about using post and beam though for a few reasons:
1. Im afraid the posts will give too much of a thermal break through the insulation.
2. Im not sure how well it stands up the earthquake shear stresses that buildings have to deal with up here.
3. Obtaining the large size posts that it requires is somewhat difficult and expensive, I can chainsaw mill from my trees on my land but the wood is very green, not good canditates for structural lumber
4. Im hesitant to use wood because eventually it will rot, no matter what you do (unless you live in a desert). My goal in building is to have it still there 500 years from now. When I was stationed in Germany I was really impressed with the 600 to 700 year old houses made of stone and mortar and were still being lived in.
5. And finally, post and beam looks like too much bloody work for one man, usually all there is available is me and my wife, and shes a tiny woman of 4 foot 9 and just over 100 lbs. She just doesnt have the strength for heavy lifting (has got the endurance of a mule tho!)

One of the things that really impressed me when pouring the footings and the cast-in-place septic tank is just how easy and versatile concrete is to work with, cast-in-place concrete wall panels just look like the easiest and most inexpensive way of accomplishing what I want to do.
Concrete is some really neat stuff, I've even got plans for a wood/coal burner using concrete, a 30 gallon and a 55 gallon drum - its even got pipes embedded in the concrete to circulate a glycol loop to a thermal storage tank. Im going to use it to heat the barn/workshop during the winter.

As far as the ferro-cement, I've been really thinking about that too... I think though a plywood/corrugated aluminum roof is a lot easier to put up, if not nearly as long-lasting, I probably will eventually go to a ferro-cement roof for the barn.

Thanks for listening to me ramble!

Dave

-- Dave (AK) (daveh@ecosse.net), June 22, 2000.