I found out the hard way that the older concrete gets, the stronger it gets.
Was trying to make a 30cm x 60cm hole in a DIY concrete wall that the last owner of my house had placed over the mains pipe that was leaking from two joints underneath it (I suspect he also DIYed the piping, given its rather unorthodox setup). I had to make room for a plumber to access it.
It was poured in the early 70s, looked pretty, well, homemade, so I figured, easy! Borrowed a concrete breaker, got to it.
3 weeks, very painful wrists from the vibration, and a hired concrete saw, later, I finished my hole.
But holy crap, I had vastly underestimated concrete.
It takes about 40 years for concrete to reach about max strength. I've also experienced the fun of it having lived in a concrete building from the 70s :)
Was trying to make a 30cm x 60cm hole in a DIY concrete wall that the last owner of my house had placed over the mains pipe that was leaking from two joints underneath it (I suspect he also DIYed the piping, given its rather unorthodox setup). I had to make room for a plumber to access it.
It was poured in the early 70s, looked pretty, well, homemade, so I figured, easy! Borrowed a concrete breaker, got to it.
3 weeks, very painful wrists from the vibration, and a hired concrete saw, later, I finished my hole.
But holy crap, I had vastly underestimated concrete.