I am about to break out concrete in the basement for a complete bathroom tie in


I have a area where the slope towards the floor drain is severe. If I were to break out that area it would be about 6ft x 8ft. My question is can I a pour a self levelling concrete on top of the existing concrete to take away some of the slope?

Put a level on the high spot and them raise the level until its level, measure down from the far end of the level to the floor. How thick will your patch be?

Maybe partially, with the proper concrete bonding material similar to some of these:
http://www.edisoncoatings.com/html/Epoxy_Bonding_Agent_for_Concre/epoxy_bonding_agent_for_concre.htm

Do as ballenger suggested, then check into the bonding agents and ensure that you have at minimum, the thickness recommended by the bonding agent manufacturer. You will most likely have to remove some of the concrete surface from the point where you have the specified min. thickness to the tie-in point, to achieve that min. thickness. If you remove none of the existing concrete, where the new concrete is less than 2 " +/- thick (unless you use a very special and expensive mix), just foot traffic will break concrete simply tapered to zero. The bonding agent should also be a type that can be used in wet/flooded environment. (Edit: changed link due problem when opened)