The goal of this research is to propose a new method of characterizing rammed-earth walls. Based on their historic building materials properties, five broad test groups were established for the characterization: chemical and mineralogical composition, physical properties, mechanical properties, particle size distribution, and dating. These determinations can, in turn, be grouped into two different types: instrumental techniques such as XRF, XRD, and SEM-EDX, as well as adaptations of standard methods (mainly UNE-EN standards) for application to these materials. As case studies where the proposed method is applied, we present our research on the rammed-earth walls in the ramparts of Seville and Malaga (Spain), clearly showing the method’s capacity for comparing and differentiating different rammed-earth walls.

In a previous study, a layer of limewash was detected over the gypsum plasterworks used to decorate different spaces of the Real Alcázar of Seville such as interior rooms, patios and outdoor galleries. In this paper its use is analysed, namely whether it improves the properties of the plasterworks and provides a protective effect, through accelerated weathering tests designed specifically to reproduce real environmental conditions. Plaster specimens with similar composition and physical characteristics to those of the original plasterworks were prepared. After the cure of the specimens, the application of a layer of limewash was made. Samples were subjected to weathering tests that consist of water absorption cycles (by capillarity and immersion) and drying. The results showed that the application of limewash did not improve the durability of the plaster significantly, although seemed to have a more protective effect against weathering by capillarity tests in the specimens prepared with a higher water/plaster ratio. In fact, after the immersion tests a great part of the limewash layer became detached, while in the plasterworks of the Real Alcázar this behaviour has not been observed. So, capillarity tests seem to be more adequate to reproduce the real weathering conditions of these ornamental elements.

This work presents a methodology for the assessment of ancient plasterworks based on traditional inspection techniques, such as organoleptic tests and chemical characterization, and also on digital tools, such as photogrammetric surveys, thermography images, and measurement of ambient conditions with thermohygrometers. This method allows not only defining the alterations detected and establishing the state of conservation but also digitalizing the plasterworks to preserve the heritage and replicate the model if necessary (i.e., replacement of a detachment piece), drawing a hypothesis of the original hidden design of the plasterwork, and conducting a chronological study about the polychromies used over time. In some cases, the assessment has shown that the liming and repolychrome interventions to which plasterworks have been subjected and the powdery state of some areas do not ensure the possibility of the complete polychromy restoration, only its preservation by taking conservation and maintenance measures.