Both salt efflorescence and cement sludge can be encountered in renovations and new construction. Both problems affect both the aesthetics and durability of the façade, but have different causes and consequently an appropriate removal technique.
Cement slurry
Cement slurry occurs when masonry is grouted or plastered. Residues of cement or grout are left on the facade. Combined with rainy weather, the residue thins and creates an unwanted haze or discoloration, giving the facade a patchy appearance. Fortunately, a cement residue can be easily removed with the correct cleaning method.
RC Cement Clean 2 with its unique formula, without hydrochloric or phosphoric acid, is specially developed to remove cement veil on masonry work. The product penetrates the cement slurry and dissolves it completely.
Salt efflorescence
When substances present in the masonry during drying, after contact with excessive water (building moisture and rain), are deposited on the surface, a white/gray haze or efflorescence may form.
We can distinguish three types of efflorescence, salt efflorescence, lime efflorescence and gypsum efflorescence. Each type requires a different treatment for removing the efflorescence.
A first common type is salt efflorescence. It occurs primarily during excessive contact with water during masonry or grouting, but can also form from rising groundwater. Water-soluble constituents are transported to the surface through the pores of both the brick and grout. As the facade dries, the salts present start to crystallize. This creates a visible white haze, also called "early" white efflorescence.
To effectively treat salt efflorescence, first thoroughly remove the salt crystals present by wiping the surface with a hard brush. This removes the loose salt crystals and prepares the surface for treatment with RC Sulfastop ZB.
RC Sulfastop ZB is an advanced liquid solution specifically designed to address salt efflorescence. This solution forms a protective barrier against salts and prevents them from migrating to the surface, keeping the facade looking clean and cared for longer.
A more persistent type of efflorescence is lime efflorescence or lime leaching. This occurs mainly in fresh masonry combined with rain. The mortar joints are excessively stressed during rain, slowing down the carbonation (the absorption of CO² from the atmosphere that gives the mortar its strength) of the free lime in the grout.
Lime bloom forms mainly in the mortar joints and continues on the sight surface of the bricks or as a narrow stain under the butt joints. This white deposit can only be removed with special acidic cleaners such as our RC Facade P.
RC Facade P is a ready-to-use, thixotropic facade cleaner with a pH value of less than 1. This cleaning agent gently but extremely effectively dissolves surface soiling or lime efflorescence. Applicable only to brick, architectural concrete and other porous, acid-resistant substrates.
A final type of efflorescence forms only after some time, namely gypsum or calcite efflorescence. In trade jargon, this is also described as "gypsumization. In this process, the calcite efflorescence has further bound with the CO² in the air and forms an insoluble plaster layer. This persistent white veil only settles after several months or even years and systematically expands.
Digestion of masonry or bricks is difficult to remove, mechanical cleaning is often the only solution.
