YTONG system aerated concrete tiles and blocks are not joined with traditional masonry mortar, but are glued with a thin-layer adhesive mortar.. Before its application, the surface of the wall should be sanded and dusted. Then the adhesive mortar is spread with a special trowel (scoop) with a width equal to the thickness of the wall. The trowel has a serrated bottom edge, thanks to which the mortar is applied in an even layer with the desired thickness of several millimeters.