You should say that sealed concrete is not only a concrete which does not let in water, you should remember that on surface of leaky concretes or on surfaces that let in appear different kinds of essences in the form of hard removed carbonate essences , mould essences appear too. It is caused by atmospheric falls as well as capillary hydration of moisture from soil. These problems take special importance during the production of dyed concretes and decorative concretes such as paving stones or different kind of concrete decoration - leading to disqualification of article. Moreover, concrete that easily lets in , in winter conditions, can be fast destructed threatening durability of every building.