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The term “street furniture” includes numerous elements (e.g. street lamps, benches, fountains, gazebos) easing city life, complementing architecture and contributing to decorate urban areas. Despite the massive presence of street furniture in the urban environment, the knowledge about its evolution through the centuries is frequently ignored or neglected. This study analyses the main metallurgical features of twenty cast iron metalworks dating back to the 19th and early 20th centuries manufactured in cast iron foundries mainly located in Italy, France and England. The experimental activity was carried out in collaboration with “Fondazione Neri – Museo Italiano della Ghisa” (Longiano, FC, Italy).The microstructure was determined by means of optical microscopy (OM), whereas the semi-quantitative chemical composition was evaluated through scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS).The experimental results highlight the lack of a shared metallurgical culture in steel industry over the last one hundred and fifty years, since non-uniform microstructural features were observed among the specimens produced in that period in the geographical areas under study.

This work evaluates the state of conservation of three artefacts of historical street furniture in cast iron, dating back to the second half of the nineteenth century and coming from foundries located in Italy, France and Great Britain. Form, distribution and size of graphite in cast irons, and the constituents of microstructures were evaluated by optical microscopy, whereas the alloy composition was determined by scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS). The same analytical technique, in association with Diffuse Reflectance Infrared Fourier Transform (DRIFT) and micro-Raman spectroscopies, was employed to characterize corrosion attack morphology, patina stratification and thickness. The protectiveness of the corrosion layers on the artefacts was evaluated by Electrochemical Impedance Spectroscopy (EIS). The results showed that the microstructure and alloy composition were similar to those frequently encountered in complex shape castings with variable wall thickness. On the corroded surfaces, the graphitization of the cast irons was detected. This phenomenon ANSWERS TO THE REVIEWERS: REVIEWER #2The authors have improved the manuscript, but some points should be enhanced. I suggest evaluating the publication after clarification of some critical issues concerning especially the electrochemical section. Please indicate pages and lines in the answers, not just using the highlighter, when making changes in the text. Introduction:-The authors added information and bibliography about the use of SEM / EDS, FTIR and Raman. In this way there is an imbalance in the literature review carried out in the introduction. I suggest introducing also the use of EIS for metals of Cultural Heritage, as it is a technique used by the authors in the work, in the same way as the others already mentioned. There are many pivotal works published in the last few years about impedance measurements carried out by the authors.As suggested by the Reviewer, the Introduction was modified by expanding the section dedicated to EIS measurements in the field of cultural heritage (page 3 lines 1-15). Experimental:-Usually the aims and the explanation of the use of certain techniques for solving a problem are added at the end of the introduction (when a dedicated section missing). In the experimental part there must be only information about the instruments used. I therefore suggest moving especially the sentence on page 3 line 42 in the final part of the introduction and possibly discussing in this context the usefulness of the joint use of DRIFT and micro raman.Following the Reviewer's suggestion, the sentence was moved to the Introduction and included in the discussion (page 3 lines 19-24).-In the recent literature on EIS analysis on metals of cultural interest when using mineral water, the composition and origin of the water itself is also indicated. This makes possible the reproducibility of the experiment in the same conditions and using the same electrolyte (in this case a cloth soaked with a natural mineral water...

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The evolution of microstructure in relation to dating and nationality of origin was investigated in twenty-four cast iron objects of street furniture produced between XIX and XX centuries in United Kingdom, France, and Italy. Chemical composition of the metalworks was evaluated by glow-discharge optical emission spectrometry. Fragments from the cast irons were analyzed by optical microscopy and scanning electron microscopy with energy-dispersive spectroscopy. Form, distribution, and size of graphite were evaluated in the microstructure according to standard EN ISO 945-1:2008. An image analysis software was employed to quantify the area fraction of graphite in the matrix, major axis, and shape factor of graphite lamellae, area fraction of manganese sulfides (ψS), area fraction of steadite, and number of eutectic cells per area unit. All data were grouped and linear discrimination analysis (LDA) was applied to assess the group assignment and the probability of correct classification for each metalwork. The results showed that the microstructural features were compatible with those of cast irons produced in the XIX and XX centuries. Values of ψS also suggested re-melting of cast irons, associated with recycling of cast iron and/or steel scraps. The high values of steadite found in the metalworks are probably due to the excellent castability required for complex shape castings in these centuries. The LDA multivariate analysis allowed to discriminate cast irons based on the year of manufacturing and the nationality of origin.

Construction materials from the internal ducts of Aqua Traiana, a still operative Roman aqueduct built in 109 AD to supply water to Rome, were characterized by optical microscopy (OM), scanning electron microscopy (SEM-EDS), X-ray powder diffraction (XRPD) and electron microprobe analysis (EMPA). Petrographic analysis and XRPD revealed that mortar aggregates are compatible with Vitruvius’ harena fossicia and allowed the distinction of the original mortars from those of the 17th-century papal restoration. The first showed an amorphous binder while the latter have a typical lime binder. By SEM-EDS and EMPA, the microstructure of mortar aggregates was analyzed and the composition of specific minerals quantified. Microanalysis testifies the Romans’ great expertise in the selection of pozzolanic building materials, giving evidence of the possible use of local tuffs from the Sabatini Volcanic District. It also confirms the exploitation of red pozzolan from the Roman Magmatic Province, specifically from the Alban Hills district. OM also proves a high compatibility with local supplies for bricks and cocciopesto. Of these, the first were fired at moderately low temperature, while the latter show an amorphous binder as in the original Trajan mortars. All building materials thus stand for similar technological choices and a coeval production.

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