The church of Saint Martin (Trujillo, Spain): Study of the stone degradation

The Church of Saint Martin is located in Trujillo (Caceres, Spain) and it was built in the 15th century. The sub-soil is of granitic type. The climate of this area is Mediterranean type and the air pollution is scarce and of little relevance in terms of stone degradation. The predominant stone in the monument is of granitic type originated from local quarries. After a careful sampling of the building, a mineralogical-petrographical analysis was performed applying the following analytical techniques: X-Ray Diffraction and Polarized Optical Microscopy. Through visual inspection it was determined that the general conservation state of the building was quite good; however grain disgregation was detected in areas affected by raising damp and therefore some sculptural decoration was ruined. Abundant saline efflorescence also existed. Furthermore, a great variety of mortars that has been used during previous restoration works was also detected. The composition of these mortars is based on lime and crushed stone, Portland cement and arid-containing plaster that could be the source of the high level of efflorescence. This study has allowed proposing some actions to protect the monument.