Consolidation of sugaring marble by hydroxyapatite: some recent developments on producing and treating decayed samples

Sassoni, Enrico ; Graziani, Gabriela ; Franzoni, Elisa ; Scherer, George W. (2016) Consolidation of sugaring marble by hydroxyapatite: some recent developments on producing and treating decayed samples. DOI 10.6092/unibo/amsacta/5710. In: Science and Art: A Future for Stone: Proceedings of the 13th International Congress on the Deterioration and Conservation of Stone. A cura di: Hughes, J. ; Howind, T.. Paisley, Scotland: University of the West of Scotland, pp. 947-954. ISBN 978-1-903978-58-0.
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Abstract

Consolidation of sugaring marble (i.e., marble affected by granular disaggregation) still lacks fully effective solutions. Consequently, the use of an innovative phosphate-based treatment, aimed at bonding calcite grains by formation of hydroxyapatite at grain boundaries, has recently been proposed. In this paper, firstly a novel method for producing artificially decayed marble samples, by contact with a heating plate, is proposed. Then, some results are presented about the effectiveness and the compatibility of two different formulations of the phosphate treatment, differing in terms of concentration of the phosphate precursor (3.0 M or 0.1 M aqueous solutions of diammonium hydrogen phosphate, DAP), possible ethanol addition to the DAP solution and number of DAP solution applications (1 or 2). The results of the study point out that the new weathering method allows to obtain specimens with a gradient in microstructural and mechanical properties with thickness, just like naturally weathered samples. Both phosphate treatments were able to significantly improve marble cohesion, without causing significant changes in thermal behaviour and aesthetic appearance after treatment. The addition of small quantities of ethanol to the DAP solution seems to be a very promising method for favouring HAP formation and improving the treatment performance.

Abstract
Document type
Book Section
Creators
CreatorsAffiliationORCID
Sassoni, EnricoUniversity of Bologna, Italyorcid.org/0000-0003-0716-510X
Graziani, GabrielaUniversity of Bologna, Italy
Franzoni, ElisaUniversity of Bologna, Italy
Scherer, George W.Princeton University, USA
Keywords
Grain loss; Thermal ageing; Thermal diffusivity; Calcium phosphates; Ethanol
Subjects
ISBN
978-1-903978-58-0
DOI
Deposit date
18 Oct 2017 07:53
Last modified
18 Oct 2017 07:53
Project name
HAP4MARBLE - Multi-functionalization of hydroxyapatite for restoration and preventive conservation of marble artworks
Funding program
EC - H2020
URI

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