What is efflorescence and how can it be cleaned from concrete surfaces?
Efflorescence is a whitish powder like deposit which often appears on concrete and clay products. This deposit is a residue of a soluble salt carried to the surface of the pavement or wall by evaporating moisture, which leaves a dry powder or calcified deposit upon drying. A phenomenon reported as early as the 1870’s, efflorescence in itself, does not affect the structural integrity of the substrate. Efflorescence usually rises after installation as a powdery substance but can also form harder patches of calcium carbonate during the manufacturing process. The later being more difficult to remove. Hard, definitive white lines or patches (some appear to have a slight bluish tinge) on paving stones must not be confused with efflorescence. These residues are “lime” and often can not be removed at all or at least without substantial damage to the substrate. These pavers should be changed for aesthetic purposes. The origin of these salts are found in the native soil, gravel or limestone pave
