I started thinking epoxy but in the end I used the Watco water based concrete sealer. The one with the grey tint. This followed a previous thread on here and I blatmailed someone who had previously used it. i had 500sq feet to do so used 2 tins. Floor was 10 year old dusty concrete. I just gave it a brush and a vacuum over to get the worst dust off them poured from the tin and pushed it around with a broom. First coat really soaked into the concrete. Second coat flowed nicely over the top. Dries to leave a surface that feels like it is plastic coated. Eight months on, no lifting, I have jacked up cars on it, left cars parked on it for lengths of time, all good. Would recommend.