The Importance of Preserving Small Heritage Sites: the Case of La Tuiza Sanctuary (Zamora, Spain)

For centuries, granite has been one of the most widely used natural stones for building heritage, especially in the north of the Iberian Peninsula. The sanctuary of La Tuiza in Lubian (Zamora, northwest of Spain), built with Calabor granite, dates from the eighteenth century and was declared an Asset of Cultural Interest in 1995. The heritage importance of this site lies in its location, on the Sanabria route (Silver Route) of the Way of St James (Camino de Santiago), attracting visitors from all over the world. This work presents the complete characterisation of the building stone of both the monument and the original quarry and the qualitative description of the main pathologies that have been detected. The capillary water absorption coefficient is twice the value in the sanctuary compared to the quarry; the open porosity, water absorption at atmospheric pressure and sound speed propagation are slightly higher, and the compressive strength value is lower in the stones of the building. These differences reveal the incipient decay processes. In terms of pathologies, biological colonisation is scattered throughout the building, affecting the north face more intensely, and on the exterior, scaling is observed on the west face. Inside the sanctuary, deterioration is related to humidity due to capillary water infiltration, which causes conspicuous stains, efflorescence and biological colonisation in the western sidewalls. The authors recommend that measures be taken to prevent further deterioration and to protect this small site in order to maintain the cultural heritage linked to the local community.