Special purpose improving additive for tile adhesives and grouts. It increases their bonding power and adhesive strength, flexibility, waterproofing, resistance to abrasion and their service life. A necessary additive when working on substrates with intense expansions and contractions because it imparts flexibility to adhesives and grouts. Also recommended as primer, for absorbent substrates and aircrete, as well as for stabilizing brittle floor cementitious mortars and filling mortars.