Bowing of marble slabs: can the phenomenon be arrested and prevented by inorganic treatments?

Sassoni, Enrico ; Andreotti, Serena ; Scherer, George W. ; Franzoni, Elisa ; Siegesmund, Siegfried (2018) Bowing of marble slabs: can the phenomenon be arrested and prevented by inorganic treatments? Environmental Earth Sciences, 77 (10). pp. 1-18. ISSN 1866-6299
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Abstract

Bowing of thin marble slabs is a phenomenon affecting both historic monuments and modern buildings. In spite of the ubiquity and destructiveness of this phenomenon, no fully satisfactory treatment is currently available to arrest and/or prevent bowing. In this study, a treatment based on formation of hydroxyapatite (HAP) was investigated as a possible route to arrest and possibly prevent bowing of Carrara marble slabs. Four different formulations of the HAP-treatment were tested and compared to ammonium oxalate and ethyl silicate (widely used in the practice of marble conservation). The treatments were applied onto pre-weathered and unweathered specimens to investigate their ability to arrest and prevent bowing, respectively. Marble behavior was studied in terms of residual strain and bowing after thermal cycles up to 90°C in dry and wet conditions. Marble cohesion was assessed before and after the thermal cycles by ultrasound. The HAP-treatments exhibited promising results, as the residual strain and the bowing after the cycles were always lower or equal to the untreated references, while marble cohesion was always higher. Surprisingly, ammonium oxalate caused marked worsening of marble thermal behavior. In the case of ethyl silicate, most of the initial benefit after consolidation was lost after the thermal cycles. In general, the results of the study point out the importance of evaluating marble thermal behavior to assess the suitability of any conservation treatment and suggest that treatments able to strengthen marble without causing excessive pore occlusion and stiffening are preferable to enhance durability to thermal cycles.

Abstract
Document type
Article
Creators
CreatorsAffiliationORCID
Sassoni, EnricoUniversity of Bologna, Italy0000-0003-0716-510X
Andreotti, SerenaUniversity of Bologna, Italy
Scherer, George W.Princeton University, USA
Franzoni, ElisaUniversity of Bologna
Siegesmund, SiegfriedUniversity of Goettingen
Keywords
Warping Marble Hydroxyapatite Calcium oxalate Thermal behavior Thermal weathering
Subjects
ISSN
1866-6299
DOI
Deposit date
25 May 2018 09:23
Last modified
22 May 2019 21:00
Project name
HAP4MARBLE - Multi-functionalization of hydroxyapatite for restoration and preventive conservation of marble artworks
Funding program
EC - H2020
URI

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