I have an ICF block I've been beating up on to learn what I can before I build my house. Kind of on a lark, I took a cut small piece of it off and glued it to the top of the block with carpenters Titebond yellow glue. Man, did that baby stick! When I broke it off every nubbin on one side broke off and remained inside the other side. The foam broke before the joint came apart. In fact I smeared some glue on the broken surfaces, stuck it back together, and it is one solidly held together piece.

Any thoughts about using Titebond to glue blocks together at the corners instead of foam adhesive? I have no idea yet which is cheaper, but I would expect the Titebond to be. It does take a few hours to set hard so that maybe could be an issue.

F2F adhesive is more practical and dries fast. One can of F2F will glue both sides of around 100' of ICF wall with the appropriate setting on the foam gun. Picture the foam can x 12 to visualize its quantity. The same test you did above with tite-bond would yield the same test with f2f, and tite-bond is slower and more expensive.