I don't use threaded rod, but hollow graphite shafts like broken arrows, with small holes groud (Dremel) into the sides like 'Swiss cheese', like every 5/8" down a line on the length of the shaft, then rotate it a bit and stagger the other holes.
Unlike a solid rod, this allows epoxy inside and outside of the rod and the holes become mechanical 'locks', so that along with the chemical epoxy bond, you get both a mechanical and chemical bond.
FYI, the biggest issues with solid all-thread rods is if TOO TIGHT in the hole you prepared, when it squeezes out all of the epoxy ... that bcomes a DRY joint and it will subsequently fail again.