I used these to break open a concrete porch. I didn't want to use a jackhammer next to the wall of my house. It worked amazingly, the concrete was between a foot and 16 inches thick. I drilled holes about 4 to 6 inches apart and the concrete broke with almost no effort. They work best with a 9/16 inch hole punch. I think it's worth noting that the concrete contained no rebar or steel reinforcement. I'm not sure how well it would work if it had an anchor.