SikaTop 501seal is the most concentrated form of the surface applied master builders solutions crystalline Waterproofing System and contains the maximum amount of specialist catalysts. SikaTop 501 seal for patch repairs and as render on old concrete surface. (Areas of application) Water tanks, reservoirs. Building basements and foundations. Swimming pools and water parks. Sewage and treatment plants. Dams,canals,tunnels,harbours. Retaining walls and sea defense walls. Concrete pipes. Is 20kg powder