Microcracking of granite feldspar during thermal artificial processes
Granite is one of the most widely used building stone and is a main component in many heritage buildings for its austere appearance and its availability as a stone of the Earth´s crust. When exposed at the Earth’s surface, thermal changes are responsible for its decay, especially in granites exposed...
| Autores: | , , |
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| Formato: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2015 |
| País: | España |
| Recursos: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/126230 |
| Acesso em linha: | http://hdl.handle.net/10261/126230 |
| Access Level: | acceso abierto |
| Palavra-chave: | Physical disintegration Feldspars Thermal shock Freeze-thaw Building stones Decay Weathering |
| Resumo: | Granite is one of the most widely used building stone and is a main component in many heritage buildings for its austere appearance and its availability as a stone of the Earth´s crust. When exposed at the Earth’s surface, thermal changes are responsible for its decay, especially in granites exposed to weathering. Feldspars, an important component of granite mineralogy, are among the most likely crystalline phases susceptible to microcracking, which, in turn, causes the disintegration of crystals lattices. Microcracks generated in granite feldspars during thermal processes such as freeze-thaw and thermal shock cycles, carried out in the laboratory, were studied to understand the decay process of granite buildings. The aim of this study is to determine microcrack propagation (both as inter- and intra-crystalline microcracks types) within feldspars (potassium feldspars and plagioclases) of two building granites located near the city of Madrid (Spain). Potassium feldspars and plagioclases developed different mechanisms of microcracking, probably, due to their microstructures and/or driven, preferentially, by crystallographic anisotropies such as twinning and zoning of the precursor mineral, and neoformation of secondary mineral phases at the expense of a primary mineral phase. By combining petrographic analysis of the studied granite stones, with physical laboratory tests (thermal shock and freeze-thaw tests), we outlined the evolution of microcracking in order to identify the potential problems that disintegration may cause to stone monuments and buildings. |
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