I bought a diamond cup grinding wheel for my 4.5" grinder to remove an acrylic stained concrete finish. The cup works great removing the acrylic stain, but it leaves the concrete highly polished and slippery. Is there a particular grinding wheel that will leave a no-slip, coarse concrete surface?
Short answer: no, at least if used as intended.
There are some cups and disks that are extremely coarse; they look like a few pebbles of abrasive stuck in random spots. But they just remove more material faster, and still leave a surface smoother than would be helpful for your purpose. The problem is the rotation and speed. The abrasive gets at the whole surface with just a little motion of the grinder.
You could do something different with a coarse cup. Hold the grinder in one spot and turn it on for just a second or so. It will grind a circle in that spot. Move the grinder to another spot and repeat. The idea is to cover the concrete with a pattern of circles. They don't need to be deep, maybe on the order of 1/16".
Another technique is to use a circular saw with a diamond cutting wheel. Adjust the blade guide so the cutting depth is very shallow (around 1/16"), and use a guide to make straight grooves at controlled locations. Grooves about 1" apart should be enough.
You could also try the opposite approach; add instead of remove. Bond a thin layer on top with a broomed finish (you would need material with high bonding strength designed for this purpose). There are also surface finishes that contain some coarse grit for traction. Or you can buy non-slip tape sold for this purpose. It is a rugged tape with a gritty surface and a serious adhesive. You put down strips about 9" apart.