Ann: FBR Quarterly Report March 2017, page-141

have you ever seen how easily mortar crumbles and breaks, it can get as weak as anything. Go buy some two pack builders epoxy from Bunnings and glue some concrete together, you'll need a sledge hammer to get it apart.

I made a concrete block retaining wall in my yard last summer and glued the capping on with that builders epoxy that comes in 2 parts and mixes as you squeeze it out. I later had to replace one glued on concrete cap and had to belt it off with a sledge hammer and destroy the cap in the process then grind the epoxy off the block under it. I don't think there is much to worry about strength wise.