Thermal Hysteresis1  Thermal Hysteresis Diagram  Marble Under Microscope
[1,2,3]

Hysteresis [his-tuh-ree-sis] is defined as the lag in response exhibited by a body reacting to changes in the forces affecting it.[a] Relating this idea to building failures, thermal hysteresis is the term used to describe the long-term response that certain types of marble display after years of thermal cycling. The stone is particularly susceptible when cut into thin slabs and used for building facades, leaving it exposed to large variations in temperature and humidity. While marble is a brittle material, it exhibits some plastic behavior over long periods of exposure.[b] Following several years of thermal expansion and contraction, panels will start to permanently bow outward, as seen in Figure 1 above. The exposed side expands at a significantly higher rate than the inside of the panel, which remains cooler and more moist. This ‘cupping’ or ‘pillowing’ increases the porosity of the panel and can reduce its flexural strength by as much as 70%, eventually leading to failure.[b] The effect is illustrated above in Figure 2 while Figure 3 shows the resulting fractures that occur at a microscopic level.

The use of marble as a cladding material for high rise buildings began in the 1960s, “when advances in stonecutting allowed thin slices to be produced.”[c] Seeing it as a “prestigious material,” architects began recommending it to wealthy clients, including Edward Durell Stone, the architect behind the Standard Oil headquarters in Chicago.[c] Later being renamed the Amoco Building and then the Aon Center, the building provides one of the best examples of thermal hysteresis. Clad with nearly 6,000 tons of Carrara marble imported from Italy, the facade lasted less than 15 years before requiring replacement. Suffering a similar fate, the “Chase Lincoln First Bank of Rochester, New York had to strip its 27-story headquarters of its Carrara marble skin in a job that took three years” to complete. “Its cachet notwithstanding, the marble was deemed worthless and dumped in a landfill.”[c]

“Studies seem to indicate that impurities, grain size, veining and other obvious orientation of the stone crystals increase a stone’s susceptibility to experience hysteretic behavior.”[b]  However, thermal hysteresis is tough to predict, necessitating frequent observations. In most cases, once hysteresis sets in, the panels have to be replaced, typically with a material other than marble so the problem does not repeat itself. In cases where a designer is determined to use marble cladding, engineered materials like StonePly – which uses a thin marble veneer fully adhered to an aluminum backing – may provide a successful solution.[d]  As a general rule though, using solid marble slabs on facades should be avoided as it poses serious safety risks and can cost millions of dollars to replace.

[3] Siegesmund, S; Ruedrich, J; Koch, A. “Marble Bowing: Comparative Studies of Three Different Public Building Facades.” Environmental Geology 56, no. 3 (December 2008): 473-494.

[b] Newlin, J; Jimenez, G. A; Hester, D; McIntosh Blank, L. “Thin Marble Facades: History, Evaluation, and Maintenance.” Structures Congress, 2010 ASCE: 1051-1062.

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