The geochemical and engineering geological properties of the tuffs used in the rock-cut cliff tombs of the Etruscan necropolis of Norchia were investigated to evaluate their susceptibility to different weathering agents and confirm their origin. For the first time, materials were characterized by X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analyses (TGA, DGA and DTG), scanning electron microscopy (SEM-EDS) and energy-dispersive X-ray fluorescence (ED-XRF), and their different origins confirmed. Tests of material properties indicate that both tuffs are poorly durable, but one of them is less susceptible to weathering. Although tombs made with the more resistant material show limited surface weathering, they undergo severe structural damage because of stress release and plant root infiltration. This, combined with the microclimatic conditions established inside river canyons, can trigger rock falls, leading ultimately to the complete destruction of these tombs.a rcm_464 229..251

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The reduction of CO 2 emission from cement industry represents a priority task in the roadmap defined for the year 2020 by the European Union (EU) Commission for a resource efficient Europe. Several research projects have been undertaken aimed at developing non-hazardous materials as partial substitute of clinker in cement formulations, but also new, low-carbon, cements fully replacing clinker. Among the new cementing materials, Si-Al geopolymers seem the most promising, in terms of CO 2 emission and mechanical and thermal properties. In this chapter, mechanochemical processing of kaolin clays to produce metakaolin (MKA) for the synthesis of Si-Al geopolymers is proposed as an alternative process to replace thermal treatments performed at 650-850°C. Results obtained show that the mechano-chemical process is also suitable to make low cost blended Si-Al geopolymers where 40% of MKA is replaced by mechano-chemically activated volcanic tuffs. The compatibility of mechano-chemistry with industrial production was investigated by building a prototype milling system that was tested in a small industrial facility producing zeolites from industrial wastes. The degree of automation allowed the prototype to work unattended for 10 months. Based on the results obtained from these tests, a milling system for a full scale production of mechano-chemically activated rock materials was designed, and its performances analysed.

The type and quality of the information provided by the direct analysis of volcanic tuffs by 1H, 29Si, and 27Al NMR were investigated. At this aim, five tuffs, characterized by different origin, bonding mechanism, and clast composition, were used as test materials. Results consistent with the different nature of the tuff matrix and mineral composition were obtained. While the relative content of Al in the crystal and amorphous phase was determined by 27Al MAS and 3Q MAS NMR, the prevalent glassy or zeolitic nature of the matrix was assessed by 29Si and 1H MAS NMR. Zeolites present at levels as low as 15% w/w were detected by 29Si MAS NMR, and in some tuffs, identification of their framework type was performed together with the determination of the Si/Al ratio and, for the first time, of their configurational entropy. Data obtained were coherent with those provided by X-ray fluorescence (XRF), X-ray powder diffraction (XPRD), thermogravimetric analysis (TGA), differential thermal gravimetry (DTG), cation exchange capacity (CEC) determinations, and scanning electron microscopy, used in both backscattering imaging mode (SEM) and for elemental analysis (SEM-EDS). Results show that, under favorable conditions, solid state NMR techniques can provide a comprehensive view of the chemical and physicochemical behavior of a tuff. A combined use of these techniques is suitable for characterization of tuffs on a routine basis, and can be particularly useful to decide if a material is suitable for industrial applications.

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