『Abstract
Conway Castle is an immense historical structure, dating back
to 1289 AC. It was built on highly dipping thickbeds of indurated
shale (argillite) and sandstone. It is surrounded by Conway Bay,
railway lines, and tall dense forests indicating high relative
humidity and rainfall in this coastal area. The castle suffers
from weathering noted as honeycomb, black crust, exfoliation,
and discoloration with white salt efflorescence at some parts;
these are diagnostic features for salt weathering as confirmed
by the laboratory investigations using scanning electron microscopy,
X-ray diffraction (XRD), point XRD, and hydrochemical analysis.
The salt is found to be from three sources, namely, water spray
from Conway Bay that is part of the Irish Sea, chemical alteration
of the mortar's carbonate content into sulfate salts by acid rain,
and wet deposition of air pollutants on the surface of the stone.
The cracks noted in the southwestern tower of this castle are
a result of landslides in this area that resulted from three factors:
(a) high dip angle of the indurated sandstone and shale thickbeds
(about 60-65゜to the south) under this castle, (b) undercutting
of these beds in the dip direction by the surface water of Conway
Bay, and (c) seismic waves generated by the trains passing close
to this castle. All these factors result in land sliding even
at a low rate; however, the net result is cracks in the tower
close to these factors.
Keywords: Dipping strata; Cracking; Honeycomb; Acid rain; Stalactite;
Wet deposition; Black case hardening』
Introduction
Field observations and sampling
Methodology
Results
Petrographic results
Petrophysical results
Hydrochemical results
Geotechnical properties of shale beds
Structural measurements
Discussion
Conclusion
Acknowledgements
References