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This paper deals with the causes of the damage found on many retaining walls built with blocks
of soft tuff, porous stones or bricks. The damage affects the external faceand is manifested
by the crumbling of the wall at a certain height from the ground, resulting in the expulsion of
parts of the wall and of the protective plaster coating.

The cause of the damage is capillarity which forces the moisture present in the underlying
ground to rise up to a certain height within the wall, which is made up of porous and permeable
material that contains voids.