# The Mortars of Florence Riverbanks: Raw Materials and Technologies of _Lungarni_ Historical Masonry
## 3 Macroscopic Description  
During the first survey, 14 masonry cores were collected from riverbanks using a wet core drilling system executed perpendicular to the face of the masonry; only one core was extracted with an incline of 45\({}^{\circ}\) (C2 bis). C1, C2, C2b, C3, C4, C5, and C6 core samples belong to _Lungarno degli Acciaiuoli_, and C7, C8, C9, C10, C11, C12, and C13 were sampled from _Lungarno delle Grazie_. The position of core sampling was selected from previous geophysical investigation that characterized complete areas of _Lungarni_. Some anomalies and voids in the riverbanks were observed: in these points the masonry cores were sampled. Particular attention was paid to historical masonry that conducts the function of a load-bearing wall and is submitted to extreme conditions of complete saturation. In Figure 2 the position of coring is reported. The core samples are composed by fine mortar and coarse aggregates. These materials were investigated through a preliminary macroscopic observation, and on some selected samples a complete mineralogical, petrographic, and physico-mechanical characterization was carried out. Figure 1: _Lungarno degli Acciaiuoli_ riverbank: currently (**a**) and after flood of 1966 (Alinari archive), the embankment viewed from Ponte Vecchio of collapse of riverbank (**b**); _Lungarno delle Grazie_ riverbank: currently (**c**) and after flood of 1966 ([PERSON] archive) (**d**). A macroscopic description was performed on site using an endoscopic and optometric survey to identify macroscopic features of the masonry and in the laboratory using a Zeiss optical stereomicroscope up to 200 magnifications. The combination of the techniques allowed identification of 4 typologies of mortar, which are named X, Y, W, and Z. In Figure 3, the macroscopic aspect of these types are reported: historic mortar with decimeter-sized coarse aggregates (type X), historic mortar with centimeter-sized coarse aggregates (type Y), modern mortar with millimeter-sized coarse aggregates (type Z), and modern mortar with centimeter-sized coarse aggregates (type W). The term historic mortar is used to indicate a mixture of a traditional binder, fine aggregates, water, and possible additives used in riverbanks as filling of the nucleus of the masonry, while the term modern mortar is used to identify modern hydraulic binder and fine aggregates mixed with water and additives. The coarse aggregates are largely composed of stone fragments, such as _Pietraforte_, _Pietra Serena_, and _Pietra Albherese_. _Pietraforte_ and _Pietra Serena_ are the most used sandstones in Florentine architecture [33; 34], while _Pietra Albherese_ is a marly limestone that in Florence was mainly used for lime production [35]. Table 1 summarizes the descriptions of each core, the position on riverbanks and the assigned macroscopic type. To carry out an initial assessment of the quality of the cores a standardized geotechnical method, the RQD index, was used [36] (Table 1). This index gives the qualitative and quantitative assessment of rock quality and degree of jointing and fracturing in a rock mass as the percentage of intact drill core pieces longer than 10 cm recovered. The quality classification based on the RQD index is divided into five classes: 0-25% (very poor quality), 25-50% (poor quality), 50-75% (fair quality), 75-90% good  
Figure 3: Macroscopic aspect of the four different macroscopic types of core samples. Figure 2: Position of core sampling: 14 masonry cores (light-blue dots) were extracted (7 core samples from _Lungarno degli Acciiauoli_ and 7 from _Lungarno delle Grazie_). (quality), and 90-100% (very good quality). In this work, the RQD index has been applied considering that the extracted carrots are composed of aggregates of dimensions from about 1 cm to 10 cm. In addition, cohesion between the binder and such aggregates is considered.