Testing of Sydney dimension sandstone for use in the conservation of heritage buildings |
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| Authors: | B J Franklin J F Young R Powell |
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| Institution: | 1. 141 Oaks Ave, Dee Why, NSW 2099, Australiabrendafranklin@bigpond.com;3. Geotechnical &4. Environmental, New South Wales Department of Finance &5. Services, Level 13, McKell Building, 2–24 Rawson Place, Sydney, NSW 2000, Australia;6. Powell &7. Associates Pty Ltd, Architects, Landscape Architects, Stone Consultants, 9a Blackheath Street, Leura, NSW 2780, Australia |
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| Abstract: | This paper deals with the scientific assessment of the physical properties of sandstone used in the conservation of Sydney's historic heritage sandstone buildings. The local Hawkesbury Sandstone has been widely used for all manner of constructions since the early days of the first settlement. In the nineteenth century, dimension sandstone quarries existed all over the Sydney region, and the demand for the stone was great. During this time, a true ‘freestone’ known as ‘yellow block’ sandstone, in which bedding planes were absent, was quarried extensively. This sandstone is also known as a ‘self-colouring’ sandstone, where the rock, although grey when quarried, turns a yellow–brown after a few months exposure to the atmosphere. It can be easily carved and was eminently suitable for the ornate Victorian architecture of the time. There are very few quarries within the Sydney region today capable of producing ‘yellow block’ sandstone. Whenever possible, sandstone from suitable building excavations, particularly on the Pyrmont Peninsula, is used for this work. Conservation work is extremely expensive and the building elements that most need replacement, the overhanging and decorative elements, are usually those that cost the most. It is essential that the most durable replacement stone be selected. Thus, a strict regime of scientific testing is used for any major conservation project, in order to determine the physical properties of possible replacement stone. This is the province of the geologist and involves visual observation in the quarry or excavation, which is a simple, cost-effective means of weeding out poor quality stones, followed by laboratory engineering tests to establish the physical parameters of a sandstone and finally, petrographic analysis. The results of such tests, combined with careful sampling, ensure the best possible quality of replacement material. |
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| Keywords: | Dimension sandstone Sydney ‘yellow block’ sandstone conservation of heritage buildings durability laboratory engineering testing petrographic analysis |
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