Installation guide volume 24

MAINTENANCE

EFFLORESCENCE PAVERS, WALLSTONES AND STEPS, SLABS AND CURBS

Efflorescence is a natural phenomenon caused by the formation of an off-white calcite on the surface of concrete products made with cement. One in the inherent components of cement is construction lime. During the concrete manufacturing process that consists of mixing cement, water, sand, coarse aggregate and chemical auxiliaries, a series of chemical reactions occur and result in the formation of a solid material: concrete. Construction lime is released during these reactions and migrates through a micro porous network towards the surface of the concrete when it is wet. This lime, once in contact with the carbonic gas present in the air, is transformed into calcite. This phenomenon is efflorescence.

The efflorescence will disappear on its own after two or three years of exposure to weather stress but it is possible to eliminate it more rapidly by cleaning the concrete product with the appropriate detergents.

However, the proper detergents must be used by properly following the manufacturers’ instructions. It is not recommended to use deter gents containing hydrochloric acid. These acids would not only dissolve the efflorescence but also attack the cement paste and irrever sibly modify the appearance of the concrete products by discoloring or changing the surface finish. We recommend the use of gluconic or phosphoric acids that will allow proper dissolution of the efflorescence while minimizing the risk of alteration within the concrete appearance. Again, it is imperative to follow all recommendations stipulated by the manufacturers as to the use of these products.

Do not hesitate to contact our technical service department for any further information.

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