(Also see Substrates, Rough Concrete, Smooth Concrete and Exterior Concrete Substrates)
Concrete is made from a mixture of cement and aggregates. It is primarily used to construct substrates on floors. Because concrete is made from a mixture of cement and aggregates, it is very compatible with cement mortars for tile.
All concrete substrates should be clean, dry and free of dust, dirt, oil, grease, paint, tar, wax, soap, concrete curing compounds, concrete color stains, concrete sealers, clear coats, loosely bonded toppings, any primers that are not MAPEI-brand, old adhesive residues (unless otherwise recommended by MAPEI), and any other substance that may prevent, reduce or affect adhesion or performance.