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Mode and extent of physical, chemical and biological deterioration processes on european marbles

Study of the phenomenon of the radical structural breakdown
of marble grain structures. This kind of destruction is
quantitively proved by ultrasonic measurements.

Marbles in the open air are greatly affected by environmental conditions. The loss of polishing, an increasing surface roughness, sugar-like sanding off and contour scaling are the main damage phenomena which can be observed on statues and building decorations. The most serious damage, however, is a complete disintegration of the marble structure which can cause the collapse of a whole statue. This risk, which is particular for marble, cannot be detected by visual inspection. It is generally accepted that physical, chemical and biological processes are interacting. From the biological point of view, pitting lichens can be responsible for rapid marble disintegration. The most important physical parameter seems to be the anisotropic thermal expansion of calcite crystal. Sulphur dioxide is obviously the most aggressive chemical agent as it influences the Zeta-Potential of the calcite surface and the contact forces between the calcite grains. Most conservation treatments on marble are carried out using acrylic resins or mixtures of them with silicon cmpounds. A few marbles have also been treated with ethyl silicate. In GERMANY, however, many marble statues or tombstones have been treated with the "PMMA Full Impregnation Method" ("IBACH Method"). The goals of the project are to study the mode and extent of deterioration processes and develop specific materials and methods of conservation. A special interest will be devoted to pilot object investigations in member countries to establish an inventory of state-of-the-art marble objects. Another main project part is to start the outdoor exposure programme. To this end, the following investigations are in progress or being planned: * Investigations on deterioration processes: Geological and mineralogical investigations by visual microscopy, scanning electron microscope (SEM) and energy dispersive X-ray analysis (EDX) Investigations on the influence of airborne fly ash particles on the sulphatation rate Determination of the Zeta-Potential and its changes during weathering Measurements of the marble strength with ultrasonic methods. * Test Methods: Laboratory exposure of marbles in weathering chambers under artificially polluted atmosphere Outdoor exposure of marbles at different sites in Europe with significantly different climates. * Conservation Investigations: Test application of tensides with and without modified silicon organic or acrylic chemicals Study of biological interactions with protective agents. The project has been running since 1991. The proceedings of annual meetings have been regularly published. Note on timescale: Start: 1990 Initial phase: 1990/1 Main project phase beginning 1991 Proposed duration min. 3 years. 1990: Final definition of the programme Selection of marble types and objects Workshop and report I. 1991: Outdoor exposition of samples Laboratory weathering tests on samples Analytical work on samples and objects Workshop and report II. 1992: Analytical work continuing Laboratory and outdoor exposure tests continuing Test application of conservation products Workshop and report III. 1993: Analytical work continuing Laboratory and outdoor exposure tests continuing Measurements on pilot objects Workshop and report IV. 1994: Analytical work continuing Laboratory and outdoor exposure tests continuing Measurements on pilot objects Workshop and report V. 1995: Analytical work continuing Laboratory and outdoor exposure tests continuing Measurements on pilot objects Workshop and report VI. 1996: Analytical work continuing Laboratory and outdoor exposure tests continuing Measurements on pilot objects Workshop and report VII. 1997: Analytical work continuing Laboratory and outdoor exposure tests continuing Measurements on pilot objects Workshop and report VIII. 1998: Analytical work continuing Laboratory and outdoor exposure tests continuing Measurements on pilot objects Workshop and report IV.
Acronym: 
EUROMARBLE
Project ID: 
496
Start date: 
01-01-1990
Project Duration: 
108months
Project costs: 
1 480 000.00€
Technological Area: 
Market Area: 

Raising the productivity and competitiveness of European businesses through technology. Boosting national economies on the international market, and strengthening the basis for sustainable prosperity and employment.