Ciment fondu

so where in the US can cement fondu be purchased, I have even called quickcrete company who put me through to one of the chemical engineers or whoever it is that designs their products, and they had no clue what cement fondu was. Is there a substitute for it?

This is quite a bit off topic here, but the NC Arboretum itself has classes in making "hypertufa" pots.  In East Tennessee you MAY be close enough to get to one of them.  Check out the Adult Education Catalog at:
http://www.ncarboretum.org/assets/File/PDFs/Education/final-Education-Catalog-Jan2013.pdf

If you can't do that, here's a video showing the procedure:

http://www.lowes.com/creative-ideas/woodworking-and-crafts/make-hypertufa-pots/project

This talks about making pots/planters.  Slabs are even easier.

You need to spell it right, ciment fondu. It's French. It has nothing whatever to do with hypertufa. I found one supplier in the US, http://www.kerneosinc.com/pdfs/new/CACMSDSUSA.pdf
They may have a retailer closer to you.
Otherwise, fake slabs are often made from Fiberglas. Contact any auto body or boat repair shop. You may be able to find the instructions online.
Iris

Try searching for rapid setting high alumina cement. That is the technical description of Ciment Fondu. It is very bad architecturally as it is prone to sudden failure and has therefore become unpopular in most uses. It is fine for making pots though. I have a couple that I made and have been weathering for more than ten years while I make the right tree!

http://www.homedepot.com/p/t/100091767?catalogId=10053&langId=-1&keyword=mortar&storeId=10051&N=5yc1v&R=100091767#.UfE5SWTF3Dk
Same exact specs as Eric uses here. Just need to put a final waterproof cement over this as the final step.