Physico‑chemical properties and alteration of Lixus historical monuments building rocks (Larache–Morocco)

This paper is a contribution to the conservation of the built heritage in Northwestern Morocco, especially the roman acheositeof Lixus in Larache. The aim is to identify the alteration forms of building rocks and to determine the agents in charge. The first part of the fieldwork consisted of rocks haracterization via a mapping procedure and a careful sampling. While the second part was inventorying the observed forms of alteration. In the laboratory, the samples were subject of a petrographic study and experiments to determine the building rock’s parameters such as; porosity, density and hardness. Furthermore, an accelerated ageing experiment due to salt crystallization, using a salt fog chamber, was relevant to run, because of the air salinity of the Mediterranean weather of North-Western Morocco. The results are that the characterization of the building
rocks reveals the use of four main lithologies: Quartz Sandstone (49%), Calcarenites (26%), Littered Sandstones (14%) and Biocalcarenites (12%). These rocks are affected by different forms of alteration like erosion, alveolization, salt efflorescence, cracks and intense biodegradation, caused by lichens (Crustaceans and Folicaea) and Cormophytes. These forms of degradation are more common on biocaclcarenites and calcarenites. Thus, the agents responsible for these athologies are external suchlike water and salt and internal like porosity, water absorption, hardness, density and mineralogical composition, in
particular CaCO3. These results provide a scientific support to select the restoration materiel at Lixus.