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REMOVAL OF STAINS FROM CONCRETE MASONRY
TEK 8-2A

With the continued use and expanding applications of architectural concrete masonry, segmental retaining wall units, and concrete pavers, exposed concrete masonry is becoming common across the country. Although maintenance of a well designed and constructed masonry wall is minimal, inadvertent staining from oil, grease, or other foreign substances can destroy the appearance of an otherwise attractive unpainted masonry structure. This publication provides information on effective methods for removing some of the most common stains.

CONTROL AND REMOVAL OF EFFLORESCENCE
TEK 8-3A

Efflorescence is a deposit of soluble salts and bases, usually white in color, that sometimes appear on the surfaces of masonry or concrete construction. Although it may be an aesthetic concern, efflorescence will not affect structural performance. Often efflorescence is apparent just after the structure is completed. If the efflorescence is essentially uniform throughout the exterior facade, it indicates normal water loss from the materials and the building. Some identify this occurrence as “early age” efflorescence or “new building bloom”. If unattended, the salts will eventually be removed by rain water.  If the deposit is heavy and essentially shows as white streaks immediately below mortar joints or covering localized areas of the masonry, it indicates that water has entered or is entering the wall at a higher elevation. These salts are called leachates, referred to “lime spots”, “lime runs” and “lime deposits”; and are sometimes identified as “late age” or recurrent efflorescence. Late age or recurrent efflorescence usually consists of more permanent surface accumulations and indicates a need for corrective measures. This TEK discusses the various mechanisms which cause efflorescence and presents recommendations for its control and removal.

CLEANING CONCRETE MASONRY
TEK 8-4A

Concrete masonry buildings offer exceptional beauty, coupled with attributes such as structural strength, durability, fire resistance, acoustic performance and low maintenance. Proper cleaning after construction and throughout the life of the building will help preserve concrete masonry's beauty. Although the maintenance needs of a well-designed and constructed masonry wall are minimal, contaminants can detract from an otherwise attractive structure. Cleaning of mortar smears, construction dirt and possibly efflorescence from the construction phase is usually required. Subsequent cleaning may be required over the life of the building to address dirt and soot from the atmosphere or staining from specific sources. Appropriate cleaning can remove contaminants and help produce a more uniform appearance. This TEK discusses several general cleaning methods, applicable to whole-wall cleaning. For information on removing stains or localized contaminants, refer to Removal of Stains From Concrete Masonry, TEK 8-2A (ref. 7).