Testing of Sydney dimension sandstone for use in the conservation of heritage buildings

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.

本文是关于对用于维修悉尼历史遗产砂岩建筑物的砂岩所进行的物理性质的科学评估。自从英国人首次定居以来，当地霍克斯伯里砂岩一直广泛用于所有方式的建筑。在十九世纪，砂岩采石场遍布悉尼地区，对石材的需求量巨大。在此期间，一种被称为“黄色巨块”砂岩的真“易劈石”被广泛开采。这种砂岩中不存在层面，而且被称为“自着色‘砂岩。它开采时呈灰色，曝光到大气中几个月后变为黄棕色。它易被雕刻，特别适用于那个时代华丽的维多利亚式建筑。现在，悉尼地区极少数采石场能够生产“黄色巨块“砂岩。只要有可能，从合适的建筑挖掘中得到的砂岩，特别是在皮尔蒙特半岛上，都用于这项工作。维修工作是极其昂贵的，最需要更换的建筑部件，悬垂的和装饰的部件，通常花费最多。至关重要的是，必须选择最耐用的替代石材。因此，严格的科学检测被用于任何重大维修项目，以确定可能替换石材的物理性能。这是地质学家的领域，涉及在采石场或挖掘地的肉眼观察来简单有效地淘汰质量差的石头；接着是实验室的工程测试，以建立砂岩的物理参数；最后，是岩相分析。这样测试的结果，并结合仔细采样，能确保替换材料的最佳质量。

Keywords:

• Dimension sandstone
• Sydney ‘yellow block’ sandstone
• conservation of heritage buildings
• durability
• laboratory engineering testing
• petrographic analysis