I've never used it, but I would give it a try.
I found several on Amazon, they all say it's as strong or stronger than concrete and definitely easier to use.
Here's oneHere's oneHere's oneIf you use one "post" about it.
I would probably try the Sika or the 2K, but no experience with either, just sharing thoughts.
Figuring out how to do something you have never done is what makes a good challenge.