RustSeal on Concrete

Last Fall I did a test patch of your product on my garage floor. I put it down right where I drive over it. Also, we live on a dirt road so the cars track in mud all Winter. All Winter, I have been grinding the road dirt into the paint. Well, its Spring and time to see how KBS did. Well, it looks like its brand new. When I broke off the caked on mud it still had a shine. So, I want to do the entire floor and the wooden shelves (2X4's and plywood). One issue, the wife says she managed to slip on the painted area more than once when it was wet/icy/muddy. What would you recommend to use as a grit in the top coat?