Marble façades structural decay due to bowing – A comprehensive review

Abstract

Natural stone has been used in façades for centuries. Initially, stone elements were rather thick when used as construction elements, and the durability was appropriate. Scientific research on the properties of marble began in the late 19th century. In the following years, the thickness of natural facade stones decreased from over 1000 mm (as in construction elements) to 20-50 mm (in cladding applications) because of new cutting technologies and equipment developed by the industry. Even though most marble claddings perform satisfactorily, durability problems have begun to appear at an increasing rate after some 50 years of using thin cladding. Well-known buildings such as the Amoco Building in Chicago, SCOR tower in Paris, and the Finlandia Hall in Helsinki have had their marble cladding replaced after less than 30 years at the cost of many millions of Euros. The deterioration gives a considerable change in the appearance of the panels. They bow, warp or break. Most cases of bowing involve Italian marble from the Carrara area, simply because it is the most widespread and used marble type. It is, however, vital to emphasize that most building facades with Carrara marble perform well, and marbles from other areas also exhibit durability problems. The bowing of marble is not only restricted to buildings and gravestones of marble are also known to bow. Nowadays, most of the well-known cases are from Europe or North America, most likely because of the much more widespread use of thin marble claddings in these regions. In Europe, there are building facades with bowed marble slabs in both the cooler climates of Finland and Denmark and the warmer climates of Portugal and Spain. Bowed slabs can also be found in Austria, Belgium, France, Germany, Greece, Italy, the Netherlands, Norway, Sweden, Switzerland, and the UK. Despite more than 100 years of research, the marble bowing problem has not been solved. Numerous works are entirely focused on the possible factors responsible for the deterioration of marble, and they clearly show that temperature variations and moisture are key factors in the degradation processes. The interaction of temperature and moisture must be a crucial external factor for the bowing and strength loss of certain marble types. Still, an updated and comprehensive review of marble façades structural decay due to bowing is not available. In this sense, there is a need to consolidate the understanding of marble bowing.