Is Hydrocal Gypsum Cement safe in marine aquariums?

[El Rifer]

Hi, I am considering taking on a diy projects for live rock for 180gal reef, and I ran into this Hydrocal Gypsum White Cement fairly cheap online and was wondering if it would be safe to use other than Portland Cement. Anyone here familiar with that brand of cement?
I would appreciate any advice anyone would have on best material to use for this. Artificial live rock manufacturers use a ceramic based cement but I can't for the life of me find or figure out what exactly they use. Ceramic would be the best way to go, what with the porosity of it and how easily it soaked up water. But I've looked everywhere for a ceramic based cement and honestly I have no clue as to what I'm really looking for. There just isn't enough information on products to know especially if it would work for the purpose I need it for, unless you contact the manufacturers. I don't know if I even want to bother, who knows how many I'd have to contact, and how long it would even take before finding the right one, if I ever do find one.
Anyways any help would be appreciated. Thanks and happy reefing.

 

[lapin]

I believe it is regular cement with gypsum added. The gypsum slows the curing (drying) process.
I have heard of making rock out of ceramic material with organic fibers added to the mix. When it is fired the material burns and leaves the rock more porus.