30 Grit Ceramic Cup Wheel on Overlay Surface
The floor is overlay concrete, very hard.
The picture shows the floor scratches by using 30 Grit Ceramic Cup Wheel.
Ceramic cup wheel is usually used when you want to 'transit' from metal grinding (though the finest metal, it still leaves deeper marks) to resin pad polishing.
The 'transition' can readily help you speed up the processing time and save time and labor work