Ziel
TO INCREASE UNDERSTANDING OF THE ENVIRONMENTAL FACTORS AND OF THE MECHANISMS RESPONSIBLE FOR THE DETERIORATION OF HISTORIC BUILDINGS AND MONUMENTS, AND TO HELP PROVIDE A SCIENTIFIC BASIS FOR CONSERVATION AND RESTORATION.
The atmospheric degradation of selected building stones has been simulated in laboratory rigs, designed, built and operated successfully to simulate separately dry deposition and wet deposition attack at appropriate presentation rates of pollutants. The core stones studied were Massangis Jaune Roche and Portland limestones, White Mansfield dolomitic sandstone, Pentelic marble and Leinster granite, in individual and coupled arrangements. A range of electronoptical, petrographic and analytical techniques was employed to analyze changes in the stone and in the run off solutions, after exposure to gases and acids used separately and in combination.
Under dry deposition conditions, the order of attack for calcareous stones depends on the relative humidity and development of a thin moisture layer on the stone surface. However, at 84% relative humidity with water dripping to produce typical run off, the order of attack is: nitrogen dioxide, sulphur dioxide and ozone greater than nitrogen dioxide and sulphur dioxide greater than sulphur dioxide and ozone greater than nitrous oxide, sulphur dioxide and ozone greater than sulphur dioxide greater than nitrogen dioxide and ozone greater than nitrous oxide and sulphur dioxide greater than nitrous oxide and ozone greater than nitrogen dioxide greater than nitrous oxide. It has been possible to identify the relative importance of certain steps in the gaseous phase, in the moisture layer on the stone and in the stone pores. Nitrogen dioxide catalyses and nitrous oxide inhibits the oxidation of sulphur dioxide to sulphate. Ozone accelerates certain of the reactions in the gaseous phase and can accelerate the processes in the aqueous phase where the oxides of copper, iron and manganese are also operative as catalysts. The combination of these various processes ensures that the highest rates of reaction are much greater than those of individual gases.
Under wet deposition conditions at pH 3.5 the order of reactivity of calcareo us stones detected as calcium in the runoff is nitrate greater than simulated acid rain greater than sulphate greater than water but, of course, more sulphate is retained in the stone than the other anions. Under the conditions used, sulphate is found deeper and lining the pores more extensively under wet deposition than dry deposition conditions. Granite under dry and wet deposition conditions, undergoes degradation through mineral transformations and microcracking, which have been studied petrographically. Coupled stones show greater degradation of the lower stone, particularly when it is granite and the upper stone is limestone, due to a longer time of wetness at the interface and because of deposition of degradation products from the upper stone onto the lower stone.
1) LABORATORY SIMULATION-FACTORIAL EXPERIMENTS, ETC :
THE DECAY OF VARIOUS TYPES OF STONE SUBJECTED TO REALISTIC LEVELS OF POLLUTANTS E.G. SO2, NOX, HC1, PARTICULATES, ETC., ARE STUDIED IN SPECIALLY CONSTRUCTED ENVIRONMENTAL CHAMBERS. ACCELERATED TESTS ARE ALSO USED WHERE APPROPRIATE.
2) CONSEQUENCES OF MATERIAL INTERACTION AND ARCHITECTURAL GEOMETRIC CONFIGURATION :
THE ROLE OF GEOMETRIC CONFIGURATION, SURFACES-FEATURES, MICRO-CLIMATE, MATERIALS INTERFACE ETC., IN THE DETERIORATION OF VARIOUS TYPES OF HISTORIC BUILDING STONES WILL BE EXAMINED BY LABORATORY SIMULATION METHODS.
3) ADVANCED METHODS OF EXAMINATION :
A RANGE OF ADVANCED TECHNIQUES, THERMAL IMAGING, OPTICAL AND ELECTRON MICROSCOPY, MECHANISMS INVOLVED.
4) APPROACHES TO CONSERVATION - PROTECTION TREATMENTS AND CONSOLIDANTS :
A LIMITED EFFORT IS DEVOTED TO THE TESTING OF SELECTED NOVEL TREATMENT TYPES.
Wissenschaftliches Gebiet
- natural scienceschemical sciencesinorganic chemistrytransition metals
- natural scienceschemical sciencesinorganic chemistryalkaline earth metals
- natural sciencesphysical sciencesopticsmicroscopyelectron microscopy
- engineering and technologyenvironmental engineeringair pollution engineering
- natural scienceschemical sciencescatalysis
Programm/Programme
Thema/Themen
Data not availableAufforderung zur Vorschlagseinreichung
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CSC - Cost-sharing contractsKoordinator
M60 1QD MANCHESTER
Vereinigtes Königreich