The application of geostatistical analysis to the prediction and modelling of the decay dynamics of masonry materials
Lead Research Organisation:
Queen's University Belfast
Department Name: Sch of Geography
Abstract
Accurate prediction of the behaviour of masonry materials is crucial for building stone conservation and future building strategies. A long established body of research has provided increased understanding of the factors that trigger stone decay and an awareness of the unpredictability of decay dynamics. It is precisely this unpredictability of stone decay processes that can present significant problems when planning conservation and future stone building strategies. Previous research by the Weathering Research Group (WRG) at Queen's University Belfast, funded through EPSRC projects has centered on surface modification of building stones and feedback mechanisms in the decay of sandstones. This has provided a conceptual model of building stone decay This research aims to quantitatively test the conceptual model through 2D spatial analysis and 3D geostatistical modelling. Data recorded at a series of stages through weathering simulations, designed with the experience of established weathering studies, will be used to investigate trigger factors such as porosity, permeability, mineralogy and the mechanisms that perpetuate stone decay. Weathering simulations will be used to investigate the effect of salt surface concentration, salt penetration and accumulation at depth, to monitor and quantify relationships between variables, to ultimately predict and model the dynamics of stone decay. The field of rock weathering has yet to take full advantage of the field of geostatistics in terms of spatial prediction and simulation. In the light of this the proposed research project is aimed at providing a quantitative basis and predictive potency for the conceptual model of rapid sandstone retreat developed within the WRG and from established weathering studies. Geostatistical techniques will be used, in combination with geological and rock weathering interpretation, to facilitate the prediction and modelling of the dynamics of stone decay.
Organisations
Publications
Buj O
(2011)
Spatial characterization of salt accumulation in early stage limestone weathering using probe permeametry
in Earth Surface Processes and Landforms
Gerrow CW
(2014)
Poulticing sandstone: implications for subsequent weathering response
in SWBSS2014
Jennifer McKinley (Author)
(2010)
Geostatistical analysis of multiple correlated variables from salt weathering simulations
Jennifer McKinley (Author)
(2009)
Spatial distribution of salt penetration in weathered sandstone
Johnston B
(2019)
Comparative investigation of the spatial distribution of past weathering impacts on sandstone masonry
in Geomorphology
McCabe S
(2011)
Dynamical instability in surface permeability characteristics of building sandstones in response to salt accumulation over time
in Geomorphology
McKinley J
(2011)
How Porosity and Permeability Vary Spatially With Grain Size, Sorting, Cement Volume, and Mineral Dissolution In Fluvial Triassic Sandstones: The Value of Geostatistics and Local Regression
in Journal of Sedimentary Research
Warke P
(2011)
Scale issues in geomorphology
in Geomorphology
| Description | This research applied spatial analysis techniques, comprising geostatistics and Geographical Information Systems (GIS), in combination with geological and rock weathering interpretation, to visualize, simulate and model the dynamics of stone decay. This provided a quantitative basis for quantifying and visualising the effects on building stones of weathering in temperate maritime climates. The findings demonstrated the importance of the spatial distribution of salts in the weathering process of stone decay. The movement of salt was found to be dependent on the composition and mobility of the salt solution; both sulphate and chloride salts accumulate in the near surface zone. Analysis of sulphate and chloride measurements show highest correlation between salts and with permeability at 6 -8cm depth in the block. This suggests that the combination of salts at this depth is effective in changing and increasing the intrinsic properties (permeability and porosity) of the stone and may result in accelerated stone decay at this depth. Chloride salts were found to concentrate at much deeper levels in the stone. These findings have significant implications for stone conservation strategies. |
| Exploitation Route | Accurate prediction of the behaviour of masonry materials is crucial for building stone conservation and future building strategies. Natural stone materials such as sandstones are not immune from the processes of weathering in the built environment and experience stone decay through disruption by granular disintegration, contour scaling and multiple flaking. The research addresses the spatial variability of rock properties as a potential contributing factor to the inconsistent nature of weathering response. This has implications for moisture movement and salt input, output and storage. It is precisely this unpredictability of stone decay processes that can present significant problems when planning conservation and future stone building strategies. The research generated a substantial database which provides information on the weathering of natural building stone from a 3D perspective. Analysis of this information provides greater understanding of the weathering process of natural sandstone buildings and allows us to model the dynamics of stone decay and predict the behaviour of masonry materials for building stone conservation and future building strategies. |
| Sectors | Construction,Environment,Culture, Heritage, Museums and Collections |
| URL | http://www.qub.ac.uk/schools/gap/Research/EnvironmentalChangeEC/ResearchandFocusGroups/Geomaterials/Geostatistics/ |
| Description | This research has shown the importance of the spatial distribution of salts in the weathering process of stone decay. The movement of salt was found to be dependent on the composition and mobility of the salt solution; both sulphate and chloride salts accumulate in the near surface zone. This suggests the combination of salts at this depth is effective in changing and increasing the intrinsic properties (permeability and porosity) of the stone and may result in accelerated stone decay at this depth. These results have been used to inform stone conservation strategies and have been validated against in situ weathered stone masonry provided from an ongoing building restoration programme. |
| First Year Of Impact | 2009 |
| Sector | Construction,Education,Environment,Culture, Heritage, Museums and Collections |
| Impact Types | Cultural,Economic |