I am planning to spread a thin layer or mortar over a tarmac driveway then cover it with gravel. The mortar is intended to secure the bottom layer of the gravel to the tarmac surface. I was thinking of using Sika Bond SBR+ to improve the adhesion between the mortar and the tarmac. Would this be suitable? If so, what would be the best way to apply it - add it to the the sand & cement during mixing, or paint it onto the driveway before spreading on the mortar?
Many thanks for any advice.