I have a concrete patio that I'd like to use as the foundation for a CMU wall. I'd like the CMUs to be tied into the patio slab with rebar. I get that the gist is to drill a hole in the slab, put rebar in the hole, and then fill it in with concrete to anchor the rebar into the hole. What size rebar should I use, and how big a hole do I need to drill? If I use 1/2" rebar, can the hole be 5/8"? 3/4"? Does it have to be 1"? etc.
I have been working with and around concrete for 20 years now. One thing is you cannot put cmu block or any other stucture on just a thin concrete pad. You must have a load bearing surface (footer) , and the specs will vary depending on soil type, frost line, and load. Second, if you wanted to dowel in to concrete you must use epoxy to anchor them. If using #4 rebar, i would go slightly larger on the bit (5/8") to allow enough epoxy for bonding and an easier initial fit.