The use and meanings of 'time of wetness' in understanding building stone decay
The use and meanings of 'time of wetness' in understanding building stone decay
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“潮湿时间”在理解建筑石材腐烂中的用途和意义
DOI：
10.1144/qjegh2012-048
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发表时间：
2013
影响因子：
1.4
通讯作者：
McCabe S
中科院分区：
文献类型：
--
作者：
McCabe S
水分是对石材腐烂性质的一种有据可查且至关重要的控制手段。 “潮湿时间”一词经常被用来描述石块潮湿的时间，以了解其对腐烂过程的影响。尽管这个术语在概念上已被证明是有用的，但不同的群体以不同的方式使用它来表示非常不同的事物。例如，石块表面的湿润时间（传统理解）可能与石块内部的湿润时间非常不同，由这些区域中湿润和干燥的不同动态控制。因此，表面润湿会定期发生（有时很快就会干燥，具体取决于一年中的时间），块内部润湿需要表面水分的积累渗透到深处（更可能在秋季和冬季），并且干燥速度要慢得多。这个相对较新但重要的观点是在气候变化的背景下提出的，对于理解在一段长时间的降水之后石头在深处可能保持潮湿的时间长度至关重要。干燥的性质和速度也与量化建筑石材表面和内部的湿润时间有关。这些与湿润时间相关的想法对腐烂过程具有影响，特别是长时间的深度湿润如何将天然建筑石材中盐风化的重点重新集中到化学作用上。讨论了有关化学变化的文献，表明在长期潮湿期间发生的化学变化本身可能很重要，会削弱石头（例如，水泥溶解或晶界弱化），并在块最终干燥时加剧盐结晶造成的物理损害。
Moisture is a well-documented, and crucial, control on the nature of stone decay. The term ‘time of wetness’ has frequently been adopted to describe how long a stone block is wet, with a view to understanding the impact of this on decay processes. Although this term has proved conceptually useful, it has been used in different ways, by different groups to mean very different things. For example, the time of wetness for a stone block surface (the traditional understanding) may be very different from that of a block interior, controlled by the different dynamics of wetting and drying in those zones. Thus, surface wetting will occur regularly (sometimes swiftly followed by drying, depending on the time of year), with block interior wetting requiring the accumulation of surface moisture to penetrate to depth (more likely in autumn and winter months), and drying out much more slowly. This relatively new but important perspective, framed in the context of climate change, is crucial to understanding the length of time stone may remain damp at depth following a period of prolonged precipitation. The nature and speed of drying is also relevant in quantifying time of wetness of both surfaces and the interior of building stones. These ideas related to time of wetness have implications for decay processes, specifically how a prolonged time of deep wetness may re-focus the emphasis of salt weathering in natural building stones toward chemical action. Literature on chemical change is discussed, suggesting that chemical change occurring during periods of prolonged wetness is likely to be significant in itself, with implications for weakening the stone (in terms of, for example, cement dissolution or grain boundary weakening) and exacerbating physical damage from salt crystallization when blocks finally dry out.