Recipe for lightweight concrete?

I am looking for a recipe for concrete that is light weight and fine enough to be cast into detail, i.e. no bubble or big gaps.

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rickharris6 years ago
Assuming you don't need the normal strength of concrete try filling it with Vermiculite There are so many variables here it makes your question hard to answer
hardlec (author)  rickharris6 years ago
I am replacing pink or blue insulation foam sheets, the most common material usually used for this purpose.
I am looking to make many copies by casting, and to make something more recyclable.
crasch1 year ago

I know you're probably not looking any longer, but for anyone else who may find this ible, look into EPScrete. It's made by mixing ground styrofoam with concrete. It can be made light enough to float on water. For fine detail, use the finest grade sand you can find, and add a plasticizer (Kongcrete) and fly-ash for workability. You can increase the detail by spraying a face coat with straight concrete, then filling the rest of the volume with EPSCrete. Consider adding basalt or fiberglass fibers for added strength and flexibility, and maybe laminate in fiberglass/basalt scrim for additional strength.

terryaaa2 years ago
gabdab5 years ago
Google search for lightweight concrete diy .
They basically made a 'foam' machine (foam like in shaving foam) that gets mixed with concrete 50% I guess .
Thaikarl5 years ago
what you want is... PaperCrete! google it, and you'll find a lot of information. there is a papercrete yahoo group also. it's basically recycled paper, water and cement. can be very light, yet strong, and with the right technique, you can make nice molded surfaces without voids.
Burf6 years ago
Try white portland cement and marble dust.
Start with a two parts marble to one part cement. Add water to the mix slowly until you reach the desired consistency for your casting.
Marble dust as the aggregate, not too sure about 'lightweight' though. There's going to be a trade-off between the fineness of the aggregate and the weight.
Marble dust is available in various screened sizes from almost a fine powder up to small chips but judging by his requirements for detail casts and no bubbles, I'd guess he can't use air entrainment or light weight aggregate such as vermiculite.
hardlec (author)  Burf6 years ago
Cement and sand or stone dust is VERY heavy. It is even heavier than coarse aggregate. Think "Floats" as a criteria.
Burf hardlec6 years ago
Concrete can float, steel can float. You need to be a little more precise in what it is you need and the answers can too be more precise.
hardlec (author)  Burf6 years ago
24 inch square tile, about 2 inches thick.
The "top" surface will be decorated with flock, trees, and railroad layout type stuff.
I want to lay tiles together with a barely noticeable seam.
The bottom must lay stable on a table top, and be "level"
I am not savvy as to making a hollow tile, but an egg crate pattern on the bottom might be possible.

PS: I know how to ignite water, and put out a match with diesel fuel. I usually don't apply anecdotal exceptions to a general rule unless it is necessary: it makes communication more complex, not more precise.

orksecurity6 years ago
I presume you've already considered materials other than concrete...?
hardlec (author)  orksecurity6 years ago
I am also looking at paper machie, which lacks strength and ability to cast.
orksecurity6 years ago
Lightweight _might_ be achievable by mixing in glass bubbles -- that's what's used for the lightweight spackle, if I remember correctly. But as I remember it, that's nasty stuff to work with...