Maintaining and Protecting Architectural Precast Concrete
Applying a waterproofing sealer to architectural precast concrete is the best way to minimize staining, dirt penetration, efflorescence and mildew and make the concrete easier to clean. The Cast Stone Institute recommends the use of silane or siloxane sealers (or blends containing each) for weatherproofing architectural cast concrete because these products penetrate the surface to form a water-repellent resin within the voids of the concrete. They can also help reduce freeze-thaw damage. (See The Concrete Network Shop Smart Guide to Buying Concrete Sealers.) To continue protection, it may be necessary to reapply sealer every few years. However, if you want the concrete to age or weather naturally, a sealer is normally not necessary.
The same products and procedures recommended for cleaning concrete can generally be used to clean architectural accents. A variety of commercial cleaners are available, with most containing detergents combined with mild solutions of phosphoric and/or muriatic acids. Be sure to test any treatment on a small, inconspicuous area prior to cleaning the entire piece. When possible, avoid using aggressive cleaning methods that can erode or change the appearance of the finish, such as high-pressure power washing, sandblasting and metal fiber brushes.
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