I use it in a mix with sand and coco for all of my burrowing scorps. 20% clay, 5% coco, 15% fine grain reptile sand, and 60% larger grain play sand. Moisten this mixture and pack it down. Let it dry out and your substrate will hold a burrow quite well. You can sculpt valleys and hill into your tank.
I'm currently using it for my Hadrurus and Androctonus. The Hadrurus really love this stuff. They have made very extensive burrows in it(and every night they dig out some more). I use a mix of the clay with sand(not really sure of the ratio, but approx. 25% clay, 75% sand). I wet it down, put a flat rock in the corner, and let it dry out completely on top(and at least half way down). Then I add the scorpion.
Think I'll try it as well. Prob have to order it online as none of the local stores seem to have in stock. Good info as I am always afraid of the coco/sand falling in on them. Guess I worry too much <grin>.
haha bill I was concerned about the same thing! Right now I have my 4 andros on sand and they're just been scraping. How big are your bicolors? I have three australis that can't be more than 3i. Are they pretty slow growers?