Frag discs?

[cpreefguy]

I want to make some concrete frag discs, but I dont know what kind of concrete to use...
GARF had some useful info, but they said to use Portland #3 cement. I went to HD and they had no idea what I was talking about...
Im not sure if Lowes would carry it or not. Ive also heard of cutting the concrete with crushed up oyster shells in order to add texture and lower the pH, I dont know where to get those either. If anybody has any info, or a good recipe for these, Id appreciate it! :)

[Jeff]

just use some regular portland cement and use some crushed coral, i got about half a bag of cement (50lb. bag) you can have if you come to the next meeting.

[loans_n_fishes]

Don't forget to let it cure in freshwater for 6-8 weeks.

[subber]

As far as oyster shells, I bought crushed oyster shells in a large bag 25lb?
to add to my chicken feed when I raised some so that they would get enough calcium in their diet to lay good eggs. If you can find a feed store, they may have what you need.