Underground salt weathering of heritage stone: lithological and environmental constraints on the formation of sulfate efflorescences and crusts
Underground salt weathering of heritage stone: lithological and environmental constraints on the formation of sulfate efflorescences and crusts
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DOI：
10.1016/j.culher.2021.02.011
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发表时间：
2021-06-11
影响因子：
3.1
通讯作者：
Oguchi, Chiaki T.
中科院分区：
文献类型：
--
作者：
Germinario, Luigi;Oguchi, Chiaki T.
盐风化是影响石材保护的最具破坏性的过程之一，也是遗产科学中广泛争论的话题。以往研究的主要对象是建筑遗产，而其他类型的资产往往被忽视，如地下文化遗产。本文介绍了一个调查的岩石腐蚀在地下环境中集中在盐风化，其模式，成分特征，并在时间和空间上的变化，旨在找到其驱动力的岩石性质和环境设置。通过岩石基质的岩相学、地球化学和岩石物理特征、小气候监测以及地下水和雨水的化学分析，综合了对盐风化和结壳的实地勘探和矿物学分析。研究的主题是日本吉见百古安娜的地下考古历史遗址，这是一个6 - 7世纪世纪的古坟和二战时期的画廊的综合体。该遗址受到强烈的盐风化作用的影响，包括风化和由混合可溶性硫酸盐组成的结壳，主要是水合的：石膏、明矾、明矾（Na）、卤石、泻根石、杂卤石、酸模石、芒硝和芒硝。它们主要来自造岩矿物和成分（黄铁矿、玻璃、长石等）的溶解。从中新世火山凝灰岩中挖掘出来的凝灰岩显示出一定的岩性多样性（例如，玻璃量和化学-矿物学组成），其控制盐组成的空间可变性。另一个主要影响因素是地下小气候，它也影响盐风化的时间变化和季节性。最里面的地下区域具有极高的相对湿度（100%），基本上不含盐，而在现场入口附近，空气温度和湿度的较大波动为盐在干燥的冬季结晶和夏季潮解创造了条件。根据每种盐相的溶解度，结晶/溶解和水合/脱水的循环可以在季节性和短期内发生，对石头造成严重的应力和损坏。(c)2021 Elsevier Masson SAS。All rights reserved.
Salt weathering is one of the most damaging processes affecting stone conservation and represents an extensively debated topic in heritage science. The main subject of previous research is the built heritage, whereas other types of assets are often neglected, such as underground cultural heritage. This paper introduces an investigation of stone decay in the subterranean environment focused on salt weathering, its patterns, compositional features, and variability in time and space, aiming at finding its driving forces in the rock properties and environmental setting. Field explorations and the mineralogical analysis of salt efflorescences and crusts were integrated by the petrographic, geochemical, and petrophysical characterization of the rock substrates, a microclimate monitoring, and the chemical analysis of groundwater and rainwater. The subject of study is the underground archaeological-historical site of Yoshimi Hyaku Ana in Japan, a complex of Kofun tombs of the 6th-7th century and galleries of the WWII era. The site is affected by intense salt weathering, involving efflorescences and crusts composed of mixed soluble sulfates, mostly hydrated: gypsum, alunogen, alum-(Na), halotrichite, epsomite, polyhalite, tamarugite, thenardite, and mirabilite. They derive principally from the dissolution of rock-forming minerals and components (pyrite, glass, feldspars, etc.) from the Miocene volcanic tuffs into which the site is excavated. The tuffs show a certain lithological diversity (e.g., glass amount and chemico-mineralogical composition) that controls the space variability of salt composition. Another major influencing factor is the underground microclimate, which also affects the time variability and seasonality of salt weathering. The innermost underground areas have an extremely high relative humidity ( 100%) and are essentially salt-free, whereas, nearby the site entrances, the wider fluctuations of air temperature and humidity create conditions for salt crystallization in the dry winter season and deliquescence in summer. Depending on the solubility of each salt phase, cycles of crystallization/dissolution and hydration/dehydration can occur both seasonally and in the short-term, causing severe stresses to the stone and damage.(c) 2021 Elsevier Masson SAS. All rights reserved.