We're just starting to remodel our living room, which has a lot of little projects that we will be doing, as well as some that contractors will be doing. The first matter of business is removing and replacing the terracotta tile that is currently on our fireplace hearth. We're removing the tile with a masonry chisel and hammer, but the material underneath the tile is presenting an issue. I don't know if it's cement or what, but it's extremely hard, and basically impossible to remove with the masonry chisel. We need a flat surface to install the new hearth material (slate tiles), and I'm not sure how to achieve that. I attached two pics of what I'm referring to.
I need some suggestions/ideas on how to remove this underlayment material. Whatever we use, I'd like to try and not damage the wood trim around the hearth, as we weren't planning on replacing that in this project.