Climate change and the greening of masonry: implications for built heritage and new build

摘要越来越多令人信服的证据表明，不列颠群岛各地的石材腐烂环境差异很大，这些气候和污染制度本身也在变化，例如，气候本身的变化，硫排放的减少，以及当地大气中NOx水平的上升。因此，迫切需要审查腐蚀过程不断变化的性质，调查推动这些变化的新的和不断发展的环境条件，并确定它们对砖石材料未来腐蚀的影响，以及对规格和补救策略的任何必要修改。在英国西北部，这种需求最为明显。事实上，建筑石块，特别是砂岩，已经对该地区发现的潮湿、往往富含盐分的环境产生了如此不利和如此迅速的反应(Smith等人。(2002年)，不可避免地会引起人们的担忧，即随着预计更温暖、更潮湿、可能更长的冬季，它们的潮湿时间增加可能会导致什么后果。简而言之，为了应对不断变化的气候和污染，我们很可能不得不从根本上重新思考我们对砖石结构腐烂和保护的理解。之所以选择石英砂岩来研究这些问题，是因为事实证明，它们对湿度和温度制度以及污染条件的细微变化很敏感，而且是高度敏感的指标。它们还提供了酸性、质地开放的条件，有利于藻类的定居。如果石制品在更长时间内保持湿润，并且不像以前那样频繁或彻底干燥，那么可以假设有许多物理和化学效应。这些问题包括：盐类(特别是高流动性盐类)的更深渗透和更多的生物定居，导致化学和物理上的活跃生物腐烂，以及难于修复的建筑物的难看污垢。因此，这项计划将建立在早期对砂岩腐化过程的研究基础上，以研究预测的气候变化对未来腐化的可能影响。要做到这一点，它将集中于湿度状况变化对石英砂岩的影响。这将把实验室模拟与环境监测和与选定砂岩建筑暴露条件有关的腐烂模式评估结合起来，与完整石块的采样和分析相联系。这项工作的核心是在北爱尔兰西部潮湿的环境中建造测试墙，并嵌入传感器系统，以监测与生物殖民有关的温度和湿度状况。这一点将通过对定植过程和可能影响石块腐烂的反馈的实验室研究，以及与长时间的砖石“深度湿润”有关的离子扩散的研究来验证。由于合作伙伴已经掌握了详细的知识，以及行业合作伙伴提供了进入正在翻新的建筑的机会，环境监测和采样将集中在整个北爱尔兰，并对苏格兰和英格兰西北部的砂岩结构进行有限的选择性采样。在对石材本身进行所有调查的基础上，是对国家和地区气候变化情景的统计缩减，与石材状况及其控制因素的测量有关。如果要将这种情景成功地转化为适应环境变化的有意义的战略，这种新的办法在更广泛的范围内至关重要。

SUMMARYThere is increasingly compelling evidence that stone decay environments vary significantly across the British Isles, and that these climatic and pollution regimes are themselves changing as, for example, climate itself changes, sulphur emissions are reduced and local levels of atmospheric NOX rise. Because of this there is an urgent need to review the changing nature of decay processes, investigate the new, and developing, environmental conditions that are driving these changes and to scope their impacts on the future decay of masonry materials and any required modifications to specification and remediation strategies. Nowhere is this need more apparent than in the northwest of the UK. The fact that building stones, especially sandstones, already react so adversely and so rapidly to the moist, often salt rich environments found in this region (Smith et al. 2002), must inevitably raise fears of what could happen as a consequence of any increase in their time of wetness associated with projected warmer, wetter and possibly longer winters. In short, in response to changing climate and pollution it is likely that we will have to radically rethink our understanding of masonry decay and conservation.Quartz sandstones have been chosen to investigate these issues because they have proven to be susceptible to, and highly sensitive indicators of, subtle changes in moisture and temperature regimes, as well as pollution conditions. They also provide acid, open-textured conditions that favour algal colonisation. If stonework were to remain wetter for longer and not dry out either as frequently or as thoroughly as before, there are a number of physical and chemical effects that could be hypothesised. These include: the deeper penetration of salts (especially those of high mobility) and increased biological colonisation leading to active biological decay, both chemical and physical, as well as unsightly soiling of buildings that is expensive to remedy.This project will therefore build on earlier research into sandstone decay processes to investigate the likely impacts of predicted climate change on future decay. To do this, it will concentrate on the effects of changes in moisture regime on quartz sandstones. This will combine laboratory simulations with environmental monitoring and the assessment of decay patterns related to conditions of exposure on selected sandstone buildings, linked to sampling and analysis of complete stone blocks. Central to this is the construction of test walls in a wet environment in the west of Northern Ireland with embedded sensor systems to monitor thermal and moisture regimes linked to biological colonisation. This will be validated against laboratory investigations of the colonisation process and the feedbacks that could affect stone decay, together with investigations of ion diffusion associated with prolonged 'deep wetness' of masonry. Because of the detailed knowledge already possessed by the partnership, and the access to buildings undergoing renovation provided by the industrial collaborator, environmental monitoring and sampling will concentrate across Northern Ireland, supported by limited selective sampling of sandstone structures in Scotland and northwest England.Underpinning all investigations into stone per se, is the statistical downscaling of national and regional climate change scenarios, linked to measurements of stone condition and the factors controlling it. This novel approach is essential at a much wider scale if such scenarios are to be successfully translated into meaningful strategies for adaptation to environmental change.