I guess no one here has a good answer for your question. You do know that for the best strength, concrete must be *slo-o-o-wly* cured? Otherwise, I suspect you may be looking for one of the polyurethane finishes since they are good for countertops. You will probably get the best answer by asking the concrete manufacturer and/or polyurethane manufacturers.

Also, Go on the 'net and google - DIY concrete countertops -lots and lots of info out there including some forum types.