Best material to join Lecablocks and granite slabs?

[BORNER]

I am going to build a low retaining wall and plan to lay granite stone slabs on top. But what should be used for jointing material? I have heard that mortar might not adhere well to granite?

 

[Rickard.]

Stone adhesive seems like an obvious choice, but it's a bit messy/sticky around finished surfaces. (It's similar to expanding foam)

Outdoor mounting adhesive should be sufficient, and it's probably where I would start testing.

 

[BORNER]

Stone adhesive seems like the obvious choice, but it's a bit scary/messy around finished surfaces. (It's somewhat like expanding foam)

Thanks, @Rickard. However, not much of the joint will be visible since the soil masses will go up a few cm on the edge of the granite curb. Is the stone adhesive more durable than the assembly adhesive in this case?

 

[Rickard.]

I believe without having compared that the stone adhesive bonds much better to the lecablock and should therefore become stronger.