The behaviour of consolidated Neapolitan yellow Tuff against salt weathering
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- 作者：Mauro F. La Russa ; Silvestro A. Ruffolo…
- 关键词：Neapolitan Tuff ; Salt weathering ; Stone consolidation ; Nanosilica
- 刊名：Bulletin of Engineering Geology and the Environment
- 出版年：2017
- 出版时间：February 2017
- 年：2017
- 卷：76
- 期：1
- 页码：115-124
- 全文大小：
- 刊物类别：Earth and Environmental Science
- 刊物主题：Geotechnical Engineering & Applied Earth Sciences; Geoengineering, Foundations, Hydraulics; Geoecology/Natural Processes; Nature Conservation;
- 出版者：Springer Berlin Heidelberg
- ISSN：1435-9537
- 卷排序：76
文摘
Salt crystallization is a strong weathering agent in porous building materials. The crystallization pressure exerted by salt crystals, growing in confined pores, is found to be one of the main causes for damage. This paper presents the results of laboratory experimentation carried out on the Neapolitan Tuff, a pyroclastic rock largely used in Campanian architecture. Several specimens, collected from a historical quarry near the city of Naples, were treated with two different consolidating products: a suspension of nanosilica in water (Syton X30®) and ethyl silicate (Estel 1000®) dispersed in organic solvent (TEOS). Untreated and treated samples were then artificially degraded using salt crystallization tests in order to assess the effectiveness of consolidation treatments. A systematic approach, including mercury intrusion porosimetry, peeling tests and point load test, was employed to evaluate the correlation between the salt crystallization and the micro-structural features of the tuff. In addition, in order to make a correlation between porous structure of materials and susceptivity to salt crystallization, the calculation of the crystallization pressures was performed. In all samples, at the early stage of crystallization, the presence of gypsum was revealed, coming from the precipitation of sulphate ions, introduced during the test, and sodium ions, coming from the zeolites within the stone. Results showed that both consolidants increase the resistance of tuff to salt crystallization, although they induce an increase in crystallization pressure. Ethyl silicate, however, shows a better behaviour in terms of superficial cohesion, even after several degradation cycles.