On 15/03/2019 15:49, Tim+ wrote:
I once broke up a similar area with just a sledge hammer. If you can lever
up a bit with a pick axe to create a tiny space underneath, its not that
hard to break up, and very satisfying.;-)

+1
I used a mixture of SDS plus with chisel and levering up and smacking
with a large sledge hammer took me about 2 or 3 days for a similar size.