Dave - sugar sand seems to be a native of Florida, maybe other places but we sure have a bunch of it. Its nothing special, just very fine sand and out of the driveway it has a little natural dirt mixed in. If you have to buy fine sand, perhaps mixing in some brown and black Tempera powder. (I use dry Tempera in all my plaster of Paris mix).
Let me know how your baking soda experiment works.
Regards,
Jon
Flouquil Aged Concrete paint and some shals for weathering will make it look jsut like concrete.