# The Mortars of Florence Riverbanks: Raw Materials and Technologies of _Lungarni_ Historical Masonry
## 4 Analytical Methods  
### Chemical, Minero-Petrographic Characterization  
The chemical, mineralogical, and petrographic characterization was performed on 2 samples for each masonry type, only considering the historic and modern mortar portions (Table 2), using the following analytical methodologies:  
* Petrographic investigation of thin sections (30 \(\upmu\)m thickness) was carried out through observation in transmitted light with an optical microscope (OM). In the case of mortars, the petrographic approach permits accurate characterization of binder, aggregate, lump, and inorganic additives and admixtures [33; 37; 38; 39; 40; 41]. In some cases, the observation of lumps in the thin section, as reported by several contributers, allows recognition of the type of carbonate rock burnt in the kiln. Lumps, indeed, can be due to binder not being well mixed in the paste, to under-burnt fragments (remnants of under-burnt limestone), to overburnt fragments of limestone, or to hydrated and carbonated overburnt fragments after the setting reaction of the mortar [33; 40; 42; 43; 44]. A Zeiss Axioscope A.1 microscope with a camera to obtain images and dedicated software for image elaboration and measuring of main characteristics of materials (AxioVision, Carl Zeiss Microscopy, LLC, White Plains, NY, USA) was used.
* X-ray diffractometry (XRD) using a Philips X'Pert PRO on powders was employed to determine the mineralogical composition using Cu anticathode (I = 1.54 A), under the following conditions: current intensity of 30 mA, voltage 40 kV, explored 20 range between 3 and 70\({}^{\circ}\), step size 0.02\({}^{\circ}\), and time to step 50 s. The XRD analyses were performed on powder bulk samples and on selected lumps.
* Thermo-gravimetric analysis (TGA) was employed for binder characterization of mortars. Some fragments of each sample were disaggregated using a porcelain pestle, and the fraction passing through a sieve with 63 \(\upmu\)m openings (ISO R 565 Series) was considered as a binder-enriched specimen. TGA was used to evaluate the presence and the amount of volatile compounds (essentially H\({}_{2}\)O, CO\({}_{2}\)) in the samples. TGA was conducted in the range 110-1000 \({}^{\circ}\)C on about 5 mg of sample, dried (silica gel as drying agent) at room temperature for at least a week under the following experimental conditions: open alumina crucibles, heating rate of 10 \({}^{\circ}\)C/min, and 30 mL/min nitrogen gas flow. TGA was used for classifying the studied samples as non-hydraulic mortars or hydraulic ones as suggested by most authors [20; 44; 45]. TGA analyses were performed using a Perkin Elmer Pyris 6 system on historic mortar samples.
* Fourier transform infrared spectroscopy (FTIR) was employed for the determination of the composition of selected lumps through a Bruker spectrometer equipped with an ATR system. The spectra obtained from the analysis of the powdered sample were acquired and processed using OPUS 7.2 software (Bruker Optics GmbH, Ettlingen, Germany). The acquisition was carried out in the spectral range between 4000 and 400 cm\({}^{-1}\), with a resolution of 4 cm\({}^{-1}\) for 24 scans.