M
MICK the Tiler
What can happen when laying over bitumen (Blackjack) is a chemical reaction can take place between the two part flexy addy and the hydrocarbons within the blackjack causing the bitumen to crystilize under the addy and once the crystals begin to form they expand and blow the tiles away from the floor. Isolating the blackjack with a primer might work provided you don't srcatch it whilst trowelling on the addy overboarding or mechanical removal would be the best option IME. another issue you may encounter is bleed through. The bitumen will bleed through the grout and the tile if it is porous like stone sending your expensive tiles a mucky brown colour.
If there is a adhesive manufacture out there that will gladly accept a warranty claim if there adhesive fails if it is used for installation over bitumen........................... I'd like to see that.
If there is a adhesive manufacture out there that will gladly accept a warranty claim if there adhesive fails if it is used for installation over bitumen........................... I'd like to see that.