The deterioration of Apuan white marble in contemporary architectural context

Abstract

Assessment of the state of conservation of the marble slabs of the Oslo Opera House and investigation of the causes of their discoloration;.• Ongoing phenomenon of calcite grains detachment, with inter- and intra-granular corrosion, due to the atmospheric conditions to which the marble slabs are exposed;.• Presence of siloxanes and oxidized by-products of a mixture of treatments identified by micro-FTIR spectroscopy;.• No migration phenomena from the cementitious bedding mortars used for cladding towards the surface. © 2018 Elsevier Masson SAS The conservation of contemporary buildings is particularly challenging as only few information about their degradation and guidelines for their maintenance are available and at the same time, despite their architectural importance, the attention and caring procedures are nοt adequate to safeguard standards. The Oslo Opera House is a high-standing contemporary architecture (opening 2008) characterized by a large ornamental pavement mainly made of Apuan marble slabs. After a few years, large parts of the marble surface suffered from a marked yellow discoloration and dirt accumulation. In this context, the current research was carried out aiming at assessing the state of conservation of the marble slabs and investigating the causes of their discoloration, to suggest possible remediation and adequate maintenance procedures. Due to the extreme microclimatic conditions, a severe inter- and intra-granular decohesion of the calcite grains can be observed by microscopic analyses, while a surface corrosion phenomenon of the crystals is in progress. The chemical analyses of surface stone material from the slabs allow the detection of deteriorated organic by-products, as a result of the degradation of previous protective treatments, excluding the correlation of iron ions concentration with the discoloration. The state of conservation gathered so far was the starting point for the development of a tailor-made cleaning methodology of the marble cladding and a complete revision of the protective treatments and ordinary maintenance protocol.