These are Wilwood Polymatrix semi metallic pads.
Is it normal that they wear like this on the edges?
I use them for the drive to the track and on the track only.

 

yes

 

yarp

 

Fair enough, thanks guys.

 

It would help to know what pads those are.

"Polymatrix" is simply a generic marketing name to a full line of pad options. The compound is marked on the back of the pad such as 15A-xxxx or 15Q-xxxx. The letter designation reflects the exact compound in use. Knowing this may help you get a more in depth answer. Pad crumbling is not uncommon however it may well be a sign of overheating that is breaking down the binding agents in the pad.