I’ve tried sh, acid,simple green. Don’t really know what caused it but I think black mulch from a flower bed .
Try F-9 BARC
I can use that for rust stains also ? I was planning on getting some for rust spots I can’t get up.
I dont believe those to be stains.
Looks like those spots were formed when the concrete was mixed and dried.
They are typical if conditions weren’t right when mixing and pouring the concrete.
If thats a job just walk away.
That’s true. If it’s not staining then it will have to be polished out with a diamond concrete pad.
@gbattle probably has some good insight…He’s the concrete guru.
From the picture, it looks like fairly new concrete. It has fresh sod on the right side and hasn’t been back filled on the left side. I can tell that it wasn’t finished by a professional because It’s about four feet wide and it should have control joints every four feet or so and it doesn’t. My opinion is that the cream has been removed from being pressure washed too soon.
It’s not new ,but cream prolly was remove by pressure. Left side is flower bed which use to have that black stained mulch. I thought that was where the stain came from . It’s my house and my wife used a pressure washer on it years ago.