Recovering the architectural heritage of the Nueva Tabarca island (Spain) by studying the durability of original and repair mortars

Abstract

Nueva Tabarca is a small island located in the Mediterranean Sea, close to the city of Alicante (SE of Spain). Although the island is mainly known for its marine reserve, its fortified village is an exceptional example of Baroque architectural heritage, mainly built with stone and lime mortars. However, in spite of the singularity of its monuments, the majority of walls and buildings of the old town of Tabarca are in an alarming state of conservation. Airborne salt, Aeolian erosion and anthropic activity are the main causes of decay. Although several restoration works were carried out during the 70’s and in the first decade of the present century, all of them have shown to be ineffective, due to the low durability of the repair materials used. To investigate the causes of such an intense decay of both original and repair mortars, a complete characterisation of these materials has been carried out, by means of both field and laboratory studies that included: diagnosis of the conservation state of buildings, mineralogical and textural analyses of mortars, and determination of mortar strength. Our investigations have demonstrated that the decay patterns found in the repaired buildings cannot be related only to the weathering conditions of the island, but also to the choice of inappropriate repair materials. Laboratory results have shown, indeed, that the original mortars are more resistant to decay processes compared to the repair mortars used, mainly because of their lower porosity and higher mechanical strength.