In this paper, the advances in the use of optical and electronic microscope for study of the minero-petrographic and microchemical features of lime binders of ancient mortars are discussed for various case studies. Mortars belonging to several historic periods and with different functions in building structures and archaeological sites were selected in order to verify the complementarity of optical and electronic microscope analyses applied to these artificial materials. The data obtained with the application of optical and microscope analyses were able to provide detailed and more precise information on the composition, structure, and texture of lime binders, highlighting the features of air hardening calcitic lime binder, air hardening magnesian lime binder, natural hydraulic lime binder, and air hardening binders with materials providing hydraulic characteristics added. Furthermore, a complete analysis and classification of the lime lumps was determined.

The earthen architecture widely spread in many countries of Europe, America, Asia, Africa, testifies to a particular material and immaterial culture. Nevertheless, it is a fragile heritage, which needs continuous maintenance. To encourage the preservation of such evidence of building techniques, an experimental campaign aimed at the development and evaluation of the performances of protective earthen plasters was undertaken. The durability of the plasters was improved through the addition of different additives, some of them traditional (such as lime and gypsum) and others innovative (geopolymers, enzymes), and resulting from industrial wastes (cement kiln dust). These additives have been selected considering low production costs and a reduced environmental impact, to improve the sustainability of the interventions. The performances of the earthen plasters in terms of efficacy (resistance to water erosion, water absorption, drilling, thermo-hygrometric cycles) and compatibility (changes in color and water vapor permeability) have been evaluated. Good performances were obtained by the different mixtures and, in particular, by those stabilized with gypsum. The results of this experimentation could find a useful application in the preservation of both ancient and new earthen built heritage.

The PietraAlberese is a marly limestone belonging to the Ligurian series (Monte Morello Formation of Eocene age). It is a material rarely mentioned in the historical Florentine architecture because the Pietraforte, the stone of the Medieval Florence and the Pietra Serena, the stone of the Renaissance, were the main lithotypes commonly used in those periods. Nevertheless, the Pietra Alberese has been widely utilized to build the town, because it is the only limestone cropping out in this part of Tuscany allowing the production of lime. In Prato and Pistoia, the Pietra Alberese was also used as stone (e.g., ashlars) in the structures and façades of many public and religious buildings. In this work, the geological setting and a mineralogical, petrographic and physical characterization of Pietra Alberese used as building stone are proposed together with a discussion about its durability. Moreover, the different compositional and macroscopic characteristics of two lithotypes (namely the sasso alberese and sasso porcino) utilized to produce the two types of lime used in the local traditional architecture (calcina dolce and calcina forte) are highlighted.

Elena Pecchioni, Fabio Fratini, Enrico Pandeli, Emma Cantisani, and Silvia Vettori . Episodes 1999;0:. https://doi.org/10.18814/epiiugs/2020/020087