Ancient and modern mortars: knowing the past to plan the future abstract

Mortars have a fundamental role in Cultural Heritage due to their use as masonry mortars plasters, substrate of mural paintings and mosaics, etc. The study and the characterization of mortars have therefore a relevant role in terms of identification, documentation, conservation and restoration; moreover the study is particularly significant for the consolidation of buildings structures, such as in the case of damages due to earthquakes. A well done characterization (chemical, mineralogical, petrographycal and physical) allows to achieve those informations useful to answer to the above mentioned problems. The nature of the binder and of the aggregate, for instance, allows to understand the possible utilisation of local materials and the level of know-how in terms of burning, slaking, composition and application. Concerning the final properties, it must be considered that the type of binder and the characteristics of the aggregate (nature, composition, shape, grain size distribution, ratio with binder) have a large influence in the durability of the mortar itself. From a mechanical point of view it is important to understand the role played by the mortars in the masonries in terms of elastic modulus and compressive strengths of the whole structures. At least any new intervention requires a compatibility between modern and ancient mortars not only for ethical issues, but also for the conservation practice (chemical, mechanical and physical aspects) especially when the substrates to be restored, are particularly precious or injection mortars are to be used for the consolidation of the structures. In conclusion the study of the ancient mortars may provide important and significant chances not only to understand the “Material Culture”, but also to give decisive informations to plan the future architectonic and structural interventions.