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The origin, development, purpose and properties of galleting: theory and practice

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posted on 2023-08-30, 14:51 authored by Colin Arnott
Galleting is the practice of inserting chips of stone into the mortar joints of masonry. Its long and enduring history is not explained by the belief that it is primarily decorative and a convincing purpose is sought. Information is not only in short supply but also inconsistent in the unsubstantiated views expressed. A detailed understanding of galleted masonry is necessary for its correct conservation. To better understand the subject a wide range of galleted mortar joints were photographed, questionnaires were sent to professionals and their views correlated and a separate convenience survey conducted. The geographical spread of galleting was plotted and the origins of galleting sought through secondary data sources. Finally, a series of new and innovative tests was devised to establish the influence of gallets on the strength and durability of lime mortar joints. A definition and taxonomy was devised to aid positive identification of galleting. Lime mortar joints are susceptible to early failure due to the slow progression of carbonation, exposure to weathering and the build-up of stresses. It was found that the incorporation of gallets into joints resolved this by significantly increasing compressive strength and reducing shrinkage. The gallets, being stronger than the mortar, accommodate the shear stresses and minimise the risk of failure. At the same time, they increase the durability of a wall and reduce damage due to weathering. Results show that galleting has been in use for many centuries, is more widespread than is generally recognised and almost certainly started out as a significant structural element in masonry construction. The true purpose of galleting and its relationship to the mortar in which it is bedded throws new light onto the use of non-hydraulic lime mortar in construction and conservation work. This will help conservationists and operatives to understand the complex nature of this traditional form of building.

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Anglia Ruskin University

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  • Accepted version

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  • eng

Thesis name

  • PhD

Thesis type

  • Doctoral

Legacy posted date

2017-09-04

Legacy creation date

2017-09-04

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Theses from Anglia Ruskin University

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