Removing Concrete

My aluminum flagpole broke near the base.  It is in the middle of a flower bed, anchored by concrete. In order to replace the flagpole, I have to remove the old concrete, so that I can set the new flagpole and pour new concrete. 

I don't want to have to chisel the old concrete. Is there a product that will dissolve the old concrete without endangering the surrounding flowers?

Thank you for your assistance.
Interesting problem.

The answer is no.  There is nothing that will dissolve concrete without harming other things.

The only thing that dissolves concrete is acid - and that is a very dangerous substance to use.

Theoretically, you could use it very slowly and carefully so that it only worked on the concrete.  Once it reacts with the concrete it becomes harmless.  If you check my website, there is a photo of a pocket knife stuck in concrete that was softened by acids. But acid requires safety clothing, goggles, etc.  Scary.

I have never heard of anyone using it this way, but you might be able to drill a hole and fill it with acid and let it work... but I strongly recommend against it.  Acid can be a very nasty substance.

One way people have been demolishing large concrete blocks without explosives is to drill holes, fill them with materials that expand, and seal the holes.  Since concrete has low strength in tension, the internal expansion causes it to break into pieces.  I am not sure what you can do at home to duplicate that.

The only readily available material like that is Gypsum.  You probably need to drill a hole that is at least 3/4 to 1 inch diameter, fill it with fluid gypsum mix, and hope it has enough expansion potential to do the job.

I have never done that so I cannot give you any exact quantities or chances of success.

Good luck.  Let me know if any of that works.