Preliminary observations on the impact of complex stress histories on sandstone response to salt weathering: laboratory simulations of process combinations
Preliminary observations on the impact of complex stress histories on sandstone response to salt weathering: laboratory simulations of process combinations
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DOI：
10.1007/s00254-006-0531-7
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发表时间：
2007-03
期刊：
影响因子：
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通讯作者：
S. Mccabe;B. Smith;P. Warke
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文献类型：
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作者：
S. Mccabe;B. Smith;P. Warke
历史悠久的砂岩结构承载着一种遗产，或者说是一种“记忆”，即石头自置于立面以来所经历的过去的压力。这种遗传，条件目前的表现，可能是由长期暴露于低幅度的背景环境因素（例如，盐风化，温度和水分循环）的组合，叠加在这些，不太频繁，但潜在的高幅度的事件或“例外”的因素（例如，石灰渲染，严重霜冻事件，火灾）。复杂的历史对历史砂岩的衰变途径的影响还不清楚，但本文试图通过使用实验室的“过程组合”的研究，以提高这种理解。石英砂岩块（Peakmoor，来自英格兰西北部）被分为经历不同历史（石灰渲染和去除，火灾和冻融循环的孤立和组合）的子集，这些子集反映了爱尔兰东北部Bonamargy Friary的真实的中世纪砂岩纪念碑的事件时间轴（McCabe等人，2006 b）。这些子集，然后进行盐风化周期使用10%的NaCl和MgSO4的盐溶液，代表“每天”的应力环境，例如，砂岩结构在沿海，或污染的城市，位置。通过收集、干燥和称重在每个循环开始时将块浸入盐溶液中时释放的碎片来监测块对盐风化的响应。结果说明了岩石衰变系统的复杂性，表明应力历史中看似微小的变化可以产生不同的响应盐风化周期。应用于现实世界的历史砂岩结构，这一概念可能有助于解释砂岩响应于单个立面上的背景环境因素的空间和时间变化，并鼓励保护人员在选择和实施保护策略时考虑应力遗传的作用。
Historic sandstone structures carry an inheritance, or a ‘memory’, of past stresses that the stone has undergone since its placement in a façade. This inheritance, which conditions present day performance, may be made up of long-term exposure to a combination of low magnitude background environmental factors (for example, salt weathering, temperature and moisture cycling) and, superimposed upon these, less frequent but potentially high magnitude events or ‘exceptional’ factors (for example, lime rendering, severe frost events, fire). The impact of complex histories on the decay pathways of historic sandstone is not clearly understood, but this paper seeks to improve that understanding through the use of a laboratory ‘process combination’ study. Blocks of quartz sandstone (Peakmoor, from NW England) were divided into subsets that experienced different histories (lime rendering and removal, fire and freeze–thaw cycles in isolation and combination) that reflected the event timeline of a real medieval sandstone monument in NE Ireland, Bonamargy Friary (McCabe et al. 2006b). These subsets were then subject to salt weathering cycles using a 10% salt solution of NaCl and MgSO4that represents the ‘every-day’ stress environment of, for example, sandstone structures in coastal, or polluted urban, location. Block response to salt weathering was monitored by collecting, drying and weighing the debris that was released as blocks were immersed in the salt solution at the beginning of each cycle. The results illustrate the complexity of the stone decay system, showing that seemingly small variations in stress history can produce divergent response to salt weathering cycles. Applied to real-world historic sandstone structures, this concept may help to explain the spatial and temporal variability of sandstone response to background environmental factors on a single façade, and encourage conservators to include the role of stress inheritance when selecting and implementing conservation strategies.