Deterioration in XI-XIV century arab ramparts (Granada, Spain)

The causes and mechanisms of degradation in the ramparts of Granada, erecte d in the XIth to XIVth centuries, have been studied via XRD, XRF, ICP, SEM, optical microscopy, and Hg-intrusion porosimetry. We have analysed structures from different periods, including inner materia l and outer surfaces, ornamentation, and possible source quarries. The tech nique employed in these ramparts was packed-earth construction, which we ha ve divided into three different types depending on the proportions and laye ring or mixing of the binder with earth. The use of these distinct methods seems to be linked to diverse historical periods, also conditioned by the e conomic prosperity of the Kingdom of Granada at the time. The main weathering agent is water, in different states and compositions, i t ruins the poorly compacted rendering mortar by provoking the loss by diss olution of calcite, which constitutes the cementing agent, with consequent disgregation. The water also facilitates the circulation of salts and binde r-alkali reactions, thus leading to changes in volume. It is therefore esse ntial to protect such walls against the action of water in order to conserv e them. Other factors to be taken into consideration include destruction or alteration due to urban development, inappropriate restorations, earthquak es, and environmental pollution.