Fall-off of Exterior Wall Tile and Mortar Coverings in Concrete Building and Its Preventive Measure

Abstract

In building, the external surface on concrete walls is covered generally with spraying materials or ceramic tiles and in between a cement mortar rendering. Since the 1964 Olympic Games held in Tokyo, due to mass production, the number of larger and taller buildings has increased. The fall-off type of failure, in which unbonded sections fall from substrate has also shown an increase. Northern Kyûshû was witness to just such an accident when in late autumn 1989, two people were killed and one injured. Immediately after that, the Japan Society for Finishings Technology organised a committee for preventive measures against these failures, of which the author is presently chairman. In this article, based on a report of the finding of this committee, the author explains the actual situation concerning preventive measures : History of materials and techniques; Diagnosis and repairing technics of exterior walls ; Guide to project and execution of fall-off proof building; Investigative studies of existing diagnosis of defects and repaired examples.