Before anyone asks . Unsealed rebar will rust , expand , flake , and crack concrete . You put it in concrete you expect to crack , so the crack can ' t expand more than a hairline because the rebar is there . you seal the crack ya know ? If concrete didn ' t crack we wouldn ' t put rebar in it . No fucken way it PREVENTS cracks . Duct tape . No . No way . no fucken way . Slab of concrete you want . and you want it to bond all nice and neat and never crack . Only red green show would tell you to slice your concrete in half with duct tape . for fucks sake the industry is in the middle of bitching that it ' s hard to get good clean round stone because chip stone lines up to form cracks and no way you want to just form a slice with duct tape to tell it to crack lol . come on OP , I love how you ' re trying , and I love you wanna share , but can we NOT get ahead of ourselves ? where did you get the idea slicing the slab in half with duct tape wouldn ' t matter ?