As the pictures show, this is a relatively harder old concrete floor. The floor is required to expose new surface by removing out the old sealing.
Our contractor had used medium bond diamond shoes, which turned out to be very slow removal, waste time and not able to reach ideal result.
We provided 16 grit extra soft bond diamond shoes with double bar which is very aggressive to touch the floor and can leave even scratch pattern.
After mounting our diamonds, the grinding produces much more dust, and the pace of the operator pushing the grinding machine was significantly faster than used to be. Customer was very satisfactory.
A small suggestion: when working on very hard concrete, don't set up the running speed of the grinder too high, 4-6 out of 9 would be better.