Best flap discs for very hard concrete?

[Miramonti]

I need to smooth down some acrylic flagstone concrete, which I understand is a pretty tough 5,000 pounds strength per sqft. Which flap discs would be best to use with an angle grinder? (composition?)

 

[herm0016]

probably a diamond grinding wheel. I used one on real flagstone and concrete a few weeks ago and it worked well.

 

[Miramonti]

probably a diamond grinding wheel. I used one on real flagstone and concrete a few weeks ago and it worked well.

I used a diamond grinding wheel, but it goes through it almost like it's butter, both the acrylic layer and the initial concrete base layer. I need a little more finesse for finer smoothing of rough spots and burrs, and so it doesn't leave round wheel marks.

I found this list of three different compositions, but are described for metals.

Ceramic Alumina – the latest innovation in abrasives, this grain micro fractures to allow a continuous supply of the sharpest cutting edges. This provides the fastest cut as well as the best utilization of the entire grain for the longest life, especially on stainless or high alloy materials.

Zirconia Alumina – an excellent blend of zirconia and aluminum oxide grain which provides a very good cut rate to cost ratio. This is a very good choice on carbon/mild steel applications.

Aluminum Oxide – the original metalworking abrasive, this product is recommended for smaller jobs where a consistent, low cost product is needed.