The internal structure of the Villamayor sandstone as it affects its use as a construction material

Abstract Villamayor sandstone has been widely used as a building material for buildings of interest to art history in Salamanca (Spain). The differences in the quality of this material, displaying different kinds of technological behaviour, are reflected by the deterioration of the buildings. We studied the mineralogy and internal structure of the stone in order to explain how far it affects its use as a construction material. X-ray diffraction, scanning differential calorimetry, scanning electron microscopy, mercury porosimetry, backscattered electron scanning image and laser diffraction for particle size analysis were the techniques used to characterize the quarried rock samples. The results obtained showed that these stones have two types of internal structure. Illite predominates over smectite in the cementing clay of one of these stones and the diameter of the pores is smaller than 10 μm. Smectite predominates in the other stone and the diameter of the pores is larger than 10 μm, while the cohesion between particles is less than in the former. Each of these types with their particular characteristics accounts for and is consistent with the variations observed in their behaviour as a building material. This understanding helps to forecast their potential weatherability.