Development of a site specific injection grout for gypsum based plaster in the Ateni Sioni church in Georgia

Potskhishvili, Taso Gvantsa (2016) Development of a site specific injection grout for gypsum based plaster in the Ateni Sioni church in Georgia. Master thesis, Scuola universitaria professionale della Svizzera italiana.

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Abstract

This research focuses on the delamination problem of the highly significant 11th century wall paintings at the church of Ateni Sioni in Georgia (Fig. 1). Delamination is a widespread wall paintings deterioration phenomenon and is due to a lack of adhesion between plaster layers or between plaster and primary support. A variety of methods have been used to address this problem and one of them is injection grouting which has been developed in the last two decades. Most of the literature describing grouting for the stabilisation of delaminating wall paintings focuses on lime-based and/or earthen-based grouting. Gypsum has never been considered for grouting even if it has been used as the constituent of wall paintings since ancient times. There is a significant lack of conservation literature regarding gypsum-based plasters, and particularly injection grouting treatment methodologies and materials. During this research grout mixtures were developed specifically for this site through a methodology which started with the identification of the site specific requirements and involved extensive laboratory testing to assess the working properties (properties of a grout in its fluid state, i.e. during the intervention) and the performance characteristics (characteristics of a harden grout, i.e. after the intervention) defined for the site. General requirements for a grout include adequate adhesion properties, in the case of Ateni where semi-horizontal and/or horizontal surfaces suffer from severe delamination. In addition, due to the gypsum sensibility to water (in which it is slight soluble) it was important to reduce the water content of the grout. This was achieved by substituting part of the water with ethyl alcohol in the dispersion medium. Laboratory testing has provided two formulations which fully satisfy the requirements set to address the delamination in Ateni. Due to the time constrains in situ testing and evaluation of the grouts is not included in this research but the issues and constrains regarding in situ testing and possible implementation were established.

Item Type: Thesis (Master)
Supervisors: Piqué, Francesca and Jornet, Alberto and Pasian, Chiara
Subjects: Costruzioni
Divisions: Dipartimento ambiente costruzioni e design > Conservazione
URI: http://tesi.supsi.ch/id/eprint/1928

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