%0 Journal Article
%A López-Arce Martínez, Paula
%A Varas Muriel, María Josefa
%A Fernández Revuelta, B.
%A Álvarez de Buergo, Mónica
%A Fort González, Rafael
%A Pérez-Soba Aguilar, Cecilia María
%T Artificial weathering of Spanish granites subjected to salt crystallization tests:Surface roughness quantification
%D 2010
%@ 0341-8162
%U https://hdl.handle.net/20.500.14352/42407
%X For hundreds of years, two types of granite (Zarzalejo and Alpedrete) from the Madrid region, Spain, havebeen extensively used as building stones. Fresh specimens of both stone types have been sampled from theirrespective quarries and subjected to sodium sulphate salt crystallization test (SCT). The resulting physicaland chemical weathering patterns have been characterized by polarized light optical and environmentalscanning electron microscopy. Water absorption under vacuum conditions and mercury intrusionporosimetry techniques were used to determine the pre- and post-SCT porosity and pore size distribution.The following non-destructive techniques were performed to assess stone durability and decay: ultrasoundvelocity (US) and surface roughness determination (SR) of intra- and inter-granular quartz, feldspar andbiotite minerals at the centre as well as at the corners and edges of specimen surfaces. Before the SCT, USvalues were lower and SR values higher in Zarzalejo (ZAR) than Alpedrete (ALP) granite. After SCT, the USvalues declined while SR rose in both types of granites, with greater average differences in ZAR than ALP forboth parameters. Feldspar and biotite and their inter-granular contacts were found to be the weakest andtherefore the most decay-prone areas of the stone.The initial SR parameters were generally higher and rose more steeply after SCT at the corners and aroundthe edges of the specimens.While behaviour was found to be similar in the two types of granite, variations were greater in ZAR, the lessdurable and more decay-prone of the two. Surface roughness measurement of mineral grains in granitestones is a very useful, in situ, non-destructive technique for quantifying salt crystallization-mediatedphysical and chemical weathering. The resulting quantification of decay and of related durability providesinsight into the future behaviour of this type of stone, commonly used in historic buildings.
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