Research and Comparative Analysis of Earth Mortars for Conservation and Restoration of Archaeological Structures. The Case of the Sant Jaume Site (Alcanar, Catalunya, Spain)

This report presents a physico-chemical characterisation of mortars used on the walls of Sant Jaume's fortified residence in the early Iron Age (c. 650-600 BC). The report includes a comparative study of various oil mortars to determine the most suitable for use in conservation-restoration campaigns at the site. The motivation is previous studies showing lime was not used as a binder and prompted experimentation with different oil mortars. The state of conservation of the architectural ensemble was evaluated by studying its deterioration factors. The physico-chemical analysis included a chemical-mineralogical characterisation, a particle size distribution, and an estimated dose of the original mortar. The initial replacement mortar were prepared for the comparative study. These specimens were grouped into two types of mortars: the first was formed by a mixture of sediment and olive oil, and the second by sediment and linseed oil. The specimens that performed better also contained linen threads or agave string. These have undergone laboratory tests to evaluate their physical-mechanical characteristics, surface hardness, and water behaviour through water drop absorption and porosity determination tests. The results allowed us to establish the possible limitations of the materials proposed for the conservation of the walls and make corrections to formulation, thus guaranteeing the optimal result in the intervention processes.