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Saint-Sauveur-en-Rue, France

Jackson M.D.,University of California at Berkeley | Vola G.,CTG Italcementi | Vsiansky D.,Masaryk University | Oleson J.P.,University of Victoria | And 3 more authors.
RILEM Bookseries | Year: 2013

Roman hydraulic maritime concretes of the central Italian coast have pumiceous volcanic ash, or pulvis Puteolanus, from the Bay of Naples as mortar pozzolan. Petrographic and mineralogical analyses of cement microstructures in relict lime, tuff, and pumice clasts suggest that pozzolanic reaction at high pH produced gel-like calcium-aluminum-silica-hydrate cements. Orthorhombic 11 Å-tobermorite, with unit cell dimensions a = 5.591(1)Å, b = 3.695(1)Å, c = 22.86(1)Å, developed in the residual cores of portlandite clasts and in certain pumiceous clasts, as well. Ettringite and calcium-chloroaluminate formed in discrete, perimetral microstructures and in the cementitious matrix. Phillipsite and chabazite cements may reflect later dissolution of alkali-rich volcanic glass at pH 9-10. The cement systems have remained stable for 2,000 years, during partial to full immersion in seawater. Vitruvius' De architectura and other ancient texts describe the raw materials of the concretes, preparation of lime, and construction of submerged wooden forms. Information concerning the materials, formulations, and installations of the concretes was apparently spread by movement of central Italian engineers around the Mediterranean but also, perhaps, by the circulation of sub-literary engineering manuals. Further analytical investigations will determine the diverse chemical processes that produced the cement microstructures, and why the harbour constructions have endured for two millennia. © RILEM 2012. Source


Ridi F.,University of Florence | Fratini E.,University of Florence | Alfani R.,CTG Italcementi | Baglioni P.,University of Florence
Journal of Colloid and Interface Science | Year: 2013

This paper reports on the analysis of the hydration kinetics of a tricalcium silicate paste cured in presence of polymers industrially used in the extrusion process of mortars. In particular, we investigated the effect of a rheology-modifying additive (a methyl hydroxy ethyl cellulose) and a superplasticizer (a polyacrylic polymer). These polymers have been added to tricalcium silicate paste, both separately and together, to understand their distinct influence on the tricalcium silicate hydration and their possible synergies. The kinetic curves have been monitored from 10 to 40. °C by means of Differential Scanning Calorimetry and fitted using the generalized Boundary Nucleation and Growth Model combined to a diffusion-limited model, to extract: induction times, reaction rates, activation energies and diffusion coefficients. As a main result, this paper contributes to the advancement of the knowledge in the field of the extrusion process of cementitious materials, providing a thermodynamic support to the empirical evaluations of the additives performances. © 2013 Elsevier Inc. Source


Aissa A.H.,CNRS Research on Catalysis and Environment in Lyon | Puzenat E.,CNRS Research on Catalysis and Environment in Lyon | Plassais A.,CTG Italcementi | Herrmann J.-M.,CNRS Research on Catalysis and Environment in Lyon | And 2 more authors.
Applied Catalysis B: Environmental | Year: 2011

This article demonstrates that photocatalytically self-cleaning mortars and concretes can additionally contribute to the elimination of volatile organic compounds (VOC's) present in indoor and outdoor atmospheres. Formaldehyde was chosen as a representative VOC air pollutant. Titania (PC-105 from Millennium Chemicals) was added in a white Portland Cement (Société Ciment Calcia) to prepare mortar samples according to a normalized methodology. A normalized steady-state was chosen after aging the samples for three months. The distribution of titania at the exposed surface of the mortar sample was quantitatively examined, using Raman spectroscopy mapping and diffuse reflectance spectroscopy. Interestingly, when varying the weight percentage of titania (with respect to the cement weight) between 0 and 10wt%, it was demonstrated that the " occurrence rate" (or presence probability) of 100% in TiO2 at the surface of the mortar was already reached at 5wt% TiO2. Direct linear correlation between UV-absorptance and Raman spectroscopy mapping spectroscopy was obtained. In parallel, the photocatalytic removal of formaldehyde, performed in a dynamic flow reactor with an in-line photoacoustic analytic spectrometer was established by the curve rate r=f(TiO2 wt%). Since concretes and mortars are solids which can be considered as " breathing materials" , which absorb and/or adsorb many compounds, it was carefully and quantitatively determined what part of formaldehyde was adsorbed and/or absorbed by the mortar, either in the dark or under UV. The real and true photocatalytic nature of the disappearance reaction relative to UV-irradiated TiO2 let us conclude that, in addition to their photocatalytic self-cleaning properties, such cementitious materials can possibly contribute to the elimination of atmospheric VOC's which may come in contact with them. © 2011 Elsevier B.V. Source


Marrocchino E.,University of Ferrara | Toffano A.,University of Ferrara | Vaccaro C.,University of Ferrara | Borsa M.,CTG Italcementi | Cangiano S.,CTG Italcementi
2nd International Conference on Sustainable Construction Materials and Technologies | Year: 2010

Use of recycled aggregates is promoted by EU with guidelines for common strategies for a correct re-use of construction and demolition (C&D) [Poon et al., 2001]. In Italy, the legislation is encouraging the re-use of C&D inert materials but, due to the scarcity of suitable plants for processing, this resource is used as a lower quality materials for low grade application. In this study, different grain-size fractions, obtained by a grain-size sorting, from a C&D processing plant in Rovigo (NE Italy), were investigated through chemical and physical testing, to evaluate their composition, assisting in the development of improved recycling methodologies for concrete. Chemical-mineralogical and physical analysis have shown that the material is roughly homogenous. Several concrete mixes were prepared using different percentage of recycled aggregate and tested. The data have shown that the introduction of 30% of inert recycled coarse fraction, substituting natural coarse aggregate, does not affect the concrete. Source


Amadelli R.,CNR Institute for Organic Syntheses and Photoreactivity | Samiolo L.,CNR Institute for Organic Syntheses and Photoreactivity | Borsa M.,CTG Italcementi | Bellardita M.,University of Palermo | And 3 more authors.
Catalysis Today | Year: 2013

N-doped TiO2 powders were prepared by two different sol-gel methods. Samples were characterised by X-ray diffraction (XRD), BET specific surface area measurements (SSA), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and Electron Paramagnetic Resonance (EPR). XPS measurements revealed a signal at 400 eV assignable to nitrogen in the form of TiNO. EPR signals are attributed to molecular NO trapped with cavities/defects possibly interacting with oxygen vacancies. The photocatalytic activity under UV and visible light was determined following the abatement of NOx and the photodegradation of 2-propanol in gas-solid systems. N-doped TiO2 showed a higher activity compared with the pristine commercial and home prepared samples under visible light irradiation. A good photoactivity in the abatement of both NO x and 2-propanol is also observed for mechanical dispersions of N-TiO2 in CaCO3 serving as a model in view of perspective application in photocatalytically active construction and architectural materials. © 2012 Elsevier B.V. All rights reserved. Source

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