Good evening engineers , actually I m really confused I poured 10 cm pcc layer and now I want to isolate the layer by rubberised bitumen emulison poly coat to protect the bottom of the rcc reinforcement coz we all know that rcc is isolated from all elevations except bottom where pcc is under the rcc but some expirenced engineer say that waterproofing the pcc weakens the friction between the rcc and the pcc

What is the best solution to do and what is the best bitumen for water proofing the foundation ???