We are replacing a bench in a shower and want to use concrete blocks. Is there any weight limit that might avoid damage to a shower pan?

We are replacing a bench in a shower and want to use concrete blocks. Is there any weight limit that might avoid damage to a shower pan?

There would be a problem if you had a plastic or fiberglass shower base but the fact that you're replacing the bench tells me that you have a tile shower.
I can see no problem in using cement blocks since this will not affect the shower pan. Good luck, Tom