The benefit of a tough skin: bullet holes, weathering, and the preservation of heritage

Projectile damage to building stone is a widespread phenomenon. Sites damaged 100 years ago during First World War still see daily use, while in a more contemporary setting numerous reports show the damage to buildings in Babylon, Mosul and Palmyra. While research has been carried out on the long-te...

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Main Authors: Mol, L, Gomez-Heras, M, Brassey, C, Green, O, Blenkinsop, T
Format: Journal article
Published: Royal Society 2017
Subjects:
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author Mol, L
Gomez-Heras, M
Brassey, C
Green, O
Blenkinsop, T
author_facet Mol, L
Gomez-Heras, M
Brassey, C
Green, O
Blenkinsop, T
author_sort Mol, L
collection OXFORD
description Projectile damage to building stone is a widespread phenomenon. Sites damaged 100 years ago during First World War still see daily use, while in a more contemporary setting numerous reports show the damage to buildings in Babylon, Mosul and Palmyra. While research has been carried out on the long-term effects of conflict such as fire damage, little is known about the protracted damage sustained through the impact of bullets, shrapnel and other metal projectiles outside of the field of engineering focussed on ceramics and metals. To investigate alterations to mineral structure caused by projectile damage, impacts were created in medium grained, well compacted, meso-porous sandstone samples using .22 calibre lead bullets shot at a distance of 20m. Half these samples were treated with a surface consolidant (Wacker OH 100), to mimic natural cementation of the rock surface. These samples were then tested for changes to surface hardness and moisture movement during temperature cycles of 15 to 65°C. Petrographic thin section analysis was carried out to investigate the microscale deformation associated with high speed impact. The results surprisingly show that stress build-up behind pre-existing cementation of the surface, as found in heritage sites that have been exposed to moisture and temperature fluctuations for longer periods of time, can be alleviated with a bullet impact. However, fracture networks and alteration of the mineral matrices still form a weak point within the structure, even at a relatively low impact calibre. This initial study illustrates the need for geomorphologists, geologists, engineers and heritage specialists to work collectively to gain further insights into the long-term impact of higher calibre armed warfare on heritage deterioration.
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spelling oxford-uuid:1d31fdcc-904e-43cb-a9cd-da216583f5572022-03-26T11:09:39ZThe benefit of a tough skin: bullet holes, weathering, and the preservation of heritageJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:1d31fdcc-904e-43cb-a9cd-da216583f557Engineering geologyMaterials scienceGeologySymplectic Elements at OxfordRoyal Society2017Mol, LGomez-Heras, MBrassey, CGreen, OBlenkinsop, TProjectile damage to building stone is a widespread phenomenon. Sites damaged 100 years ago during First World War still see daily use, while in a more contemporary setting numerous reports show the damage to buildings in Babylon, Mosul and Palmyra. While research has been carried out on the long-term effects of conflict such as fire damage, little is known about the protracted damage sustained through the impact of bullets, shrapnel and other metal projectiles outside of the field of engineering focussed on ceramics and metals. To investigate alterations to mineral structure caused by projectile damage, impacts were created in medium grained, well compacted, meso-porous sandstone samples using .22 calibre lead bullets shot at a distance of 20m. Half these samples were treated with a surface consolidant (Wacker OH 100), to mimic natural cementation of the rock surface. These samples were then tested for changes to surface hardness and moisture movement during temperature cycles of 15 to 65°C. Petrographic thin section analysis was carried out to investigate the microscale deformation associated with high speed impact. The results surprisingly show that stress build-up behind pre-existing cementation of the surface, as found in heritage sites that have been exposed to moisture and temperature fluctuations for longer periods of time, can be alleviated with a bullet impact. However, fracture networks and alteration of the mineral matrices still form a weak point within the structure, even at a relatively low impact calibre. This initial study illustrates the need for geomorphologists, geologists, engineers and heritage specialists to work collectively to gain further insights into the long-term impact of higher calibre armed warfare on heritage deterioration.
spellingShingle Engineering geology
Materials science
Geology
Mol, L
Gomez-Heras, M
Brassey, C
Green, O
Blenkinsop, T
The benefit of a tough skin: bullet holes, weathering, and the preservation of heritage
title The benefit of a tough skin: bullet holes, weathering, and the preservation of heritage
title_full The benefit of a tough skin: bullet holes, weathering, and the preservation of heritage
title_fullStr The benefit of a tough skin: bullet holes, weathering, and the preservation of heritage
title_full_unstemmed The benefit of a tough skin: bullet holes, weathering, and the preservation of heritage
title_short The benefit of a tough skin: bullet holes, weathering, and the preservation of heritage
title_sort benefit of a tough skin bullet holes weathering and the preservation of heritage
topic Engineering geology
Materials science
Geology
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