I'd go for a cement based addy like
BAL Single Part Flexible
A flexible, non-slip, water-resistant and frost-resistant wall and floor tile adhesive, especially suitable for fixing tiles, including fully vitirfied and porcelain tiles to low porosity backgrounds/bases. Suitable for use on concrete/brick/block walling, cement:sand rendering, plaster, plasterboard, cement sheets, tile backer boards, concrete bases, cement:sand screeds, plywood overlay, ceramic/quarry tile/terrazzo/hard natural stone, vinyl tiles/sheet bases, mastic asphalt. Conforms to BS EN 12004, Type C, Class 2T.