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Featured researches published by M. Raimondo.


Waste Management | 2009

Recycling PC and TV waste glass in clay bricks and roof tiles

Michele Dondi; Guia Guarini; M. Raimondo; Chiara Zanelli

Disposal of PC monitors and TV sets is a growing problem, with over 40% of the weight of these systems comprised of waste glasses with high Pb (funnel) or Ba-Sr concentrations (panel), making them unsuitable for recycling and manufacturing new glass. A possible way to re-use these glasses is in the manufacturing of clay bricks and roof tiles. This possibility was appraised by laboratory simulation of the brickmaking process and technological characterization of unfired and fired products. The recycling of both funnel and panel glasses into clay bodies is technologically feasible, resulting in a substantially reduced plasticity behaviour during shaping-drying (implying a reduction of mechanical strength), and a promotion of sintering during firing. No significant release of Pb, Ba, and Sr was observed during the firing and leaching test for the carbonate-poor body; in contrast, some Pb volatilization during firing and Sr leaching were observed for the carbonate-rich body. Additions of 2 wt.% appear to be practicable, while 5 wt.% glass induces unacceptable modifications of technological properties. The recommended amount is within 2 and 4 wt.%, depending on the characteristics of the clay bodies. The main constraint is that the glass must have a particle size below the limit of the pan mills used in brickmaking (<1mm).


Applied Clay Science | 2002

The influence of shaping and firing technology on ceramic properties of calcareous and non-calcareous illitic–chloritic clays

María Isabel Carretero; Michele Dondi; Bruno Fabbri; M. Raimondo

Abstract Two very different illitic–chloritic clays (calcareous and non-calcareous), both currently used in the Italian brickmaking industry, were used. Technological testing consisted in a simulation of the industrial processing performed at a laboratory scale. The pieces were obtained by three shaping techniques, pressing, extrusion and moulding, and fired at 1000 and 1100 °C, in fast and slow heating cycles. In each case their technological properties were studied. The microstructure and technological parameters of the ceramic pieces vary greatly, depending on the clay composition and the processing techniques. Pressing always produces pieces made from non-calcareous clay with the lowest drying and firing shrinkage, open porosity and water absorption. As it regards the calcareous clay, the lowest values of drying and firing shrinkage and water absorption are obtained by extrusion and moulding, respectively. The mechanical resistance, pore size distribution and critical pore diameter do not reflect clearly the influence of shaping techniques. Independently from the shaping technique adopted, all non-calcareous bodies show higher Maages indexes than the calcareous ones. In any case, the Maages durability factor is higher in extruded samples.


Journal of Environmental Management | 2011

Technological behaviour and recycling potential of spent foundry sands in clay bricks

R. Alonso-Santurde; A. Andrés; Javier R. Viguri; M. Raimondo; Guia Guarini; Chiara Zanelli; Michele Dondi

The feasibility of recycling spent foundry sand in clay bricks was assessed in laboratory, pilot line and industrial trials, using naturally occurring sand as a reference. Raw materials were analyzed by X-ray fluorescence, X-ray diffraction, particle size distribution, and leaching and combined to produce bodies containing up to 35% wt. sand. The extrusion, drying and firing behaviour (plasticity, drying sensitivity, mechanical strength, bulk density, water absorption, and shrinkage) were determined. The microstructure, phase composition, durability and leaching (EN 12457, granular materials, end-life step, European Waste Landfill Directive; NEN 7345, monolithic materials, use-life step, Dutch Building Material Decree) were evaluated for bricks manufactured at optimal firing temperature. These results demonstrate that spent foundry sand can be recycled in clay bricks. There are no relevant technological drawbacks, but the feasibility strongly depends on the properties of the raw materials. Spent foundry sand may be introduced into bricks up to 30% wt. Most of the hazardous elements from the spent foundry sand are inertized during firing and the concentrations of hazardous components in the leachates are below the standard threshold for inert waste category landfill excepting for chromium and lead; however, their environmental risk during their use-life step can be considered negligible.


Journal of The European Ceramic Society | 2002

Orimulsion fly ash in clay bricks—part 2: technological behaviour of clay/ash mixtures

Michele Dondi; Guia Guarini; M. Raimondo; I. Venturi

Abstract In order to appraise the technological feasibility of the Orimulsion ash recycling in clay bricks, a laboratory simulation of the brickmaking process was carried out with various clay/ash mixtures up to 6% waste. Two different clays were selected and mixes were characterized by XRF, XRPD, TGA–DTA, TDA and PSD analyses. Plasticity, extrusion and drying behaviour, and mechanical strength, were determined on unfired mixtures, while shrinkage, water absorption, bulk density, modulus of rupture, pore size distribution, microstructure and phase composition were measured on fired bricks. Orimulsion ash caused some detrimental changes of technological properties of both unfired and fired products, concerning particularly plasticity, drying rate and drying sensitivity, porosity and colour. These effects were slightly different on the two raw materials, the carbonate-rich clay being less sensitive to the presence of ash with respect to the carbonate-free clay. In all events, drawbacks appeared to be tolerable, in technological terms, for low waste additions, approximately 1–2% ash.


Construction and Building Materials | 2003

Water Vapour Permeability of Clay Bricks

Michele Dondi; Paolo Principi; M. Raimondo; Giorgio Zanarini

Abstract The water vapour permeability of clay bricks has been experimentally measured in order to draw a representative outline of industrial products without pore-forming additives. The correlations between water vapour permeability and the main compositional and microstructural parameters of both bricks and clay bodies have been investigated. A statistical model was set up in order to predict with reasonable precision and reliability, the water vapour permeability on the basis of open porosity, bulk density, mean pore size and pore specific surface values of bricks, and the finer particle size of clay bodies.


Journal of The European Ceramic Society | 2002

Orimulsion fly ash in clay bricks—part 1: composition and thermal behaviour of ash

Michele Dondi; G. Ercolani; Guia Guarini; M. Raimondo

Abstract A bitumen-in-water emulsion (Orimulsion) is currently used as a fuel in several thermal power plants worldwide. Orimulsion combustion produces a fly ash rich in S, Mg, V and Ni, which is processed to recover metals. In order to assess the feasibility of a recycling in clay brick production, a characterization of the physico-chemical and thermal properties of ash was performed by ICP–OES, XRPD, SEM, BET and TGA–DTA techniques. Orimulsion ash resulted in fine-grained (aggregates of submicronic particles), highly hygroscopic, constituted mainly of magnesium sulphate, vanadyl sulphates and magnesium and nickel oxides, and thermally unstable in the usual brick firing conditions. These features can affect the brickmaking process, particularly the plasticity of the clay body and its drying and firing behaviour; furthermore, a mobilization of sulphates could occur, promoting the formation of efflorescence and/or the SOx release during firing.


Applied Clay Science | 2001

Chemical, mineralogical and ceramic properties of kaolinitic materials from the Tresnuraghes mining district (Western Sardinia, Italy)

Michele Dondi; Guia Guarini; Paola Ligas; M. Palomba; M. Raimondo

Abstract Kaolinitic materials crop out in the Tresnuraghes mining district (Western Sardinia, Italy). Three main kaolinitic deposits, located in the Patalza, Salamura and Su Fongarazzu areas, respectively, were investigated in order to assess their potential in the ceramic industry. The parent rock-types of this raw material are the Oligocene–Miocene rhyolitic–rhyodacitic ignimbrites. Chemical and mineralogical analyses were performed on representative samples of each deposit, by XRD and XRF methodologies. The chemical analyses generally show high silica and low alumina contents in all samples, typical of weakly kaolinized materials. The main mineralogical association consists of kaolinite and cristobalite with quartz and smectite as the minor components. Alunite may be present as a main mineral in the Salamura and Su Fongarazzu deposits, making these clay materials unsuitable for ceramic applications. The Patalza deposit exhibits low iron and sulphur contents, but low plasticity and excessive refractoriness. The Patalza materials can be used as unconventional raw materials to replace both kaolin and silica in white-firing bodies. Results show that the introduction of the Patalza “kaolins” was well tolerated in bodies for tableware, wall and floor tiles, without significant changes in porosity, bulk density, pore size distribution and coefficient of thermal expansion. The main drawback of using the Patalza material is the slight increase of firing shrinkage, while the main advantage is a systematic increase in mechanical resistance.


ACS Applied Materials & Interfaces | 2015

A Mechanistic Explanation of the Peculiar Amphiphobic Properties of Hybrid Organic–Inorganic Coatings by Combining XPS Characterization and DFT Modeling

Alessandro Motta; Oliviero Cannelli; Alice Boccia; Robertino Zanoni; M. Raimondo; Aurora Caldarelli; Federico Veronesi

We report a combined X-ray photoelectron spectroscopy and theoretical modeling analysis of hybrid functional coatings constituted by fluorinated alkylsilane monolayers covalently grafted on a nanostructured ceramic oxide (Al2O3) thin film deposited on aluminum alloy substrates. Such engineered surfaces, bearing hybrid coatings obtained via a classic sol-gel route, have been previously shown to possess amphiphobic behavior (superhydrophobicity plus oleophobicity) and excellent durability, even under simulated severe working environments. Starting from XPS, SEM, and contact angle results and analysis, and combining it with DFT results, the present investigation offers a first mechanistic explanation at a molecular level of the peculiar properties of the hybrid organic-inorganic coating in terms of composition and surface structural arrangements. Theoretical modeling shows that the active fluorinated moiety is strongly anchored on the alumina sites with single Si-O-Al bridges and that the residual valence of Si is saturated by Si-O-Si bonds which form a reticulation with two vicinal fluoroalkylsilanes. The resulting hybrid coating consists of stable rows of fluorinated alkyl chains in reciprocal contact, which form well-ordered and packed monolayers.


Key Engineering Materials | 2004

Influence of Strengthening Components on Industrial Mixture of Porcelain Stoneware Tiles

Chiara Zanelli; Michele Dondi; Guia Guarini; M. Raimondo; I. Roncarati

A typical industrial formulation for porcelain stoneware tiles was modified by adding synthetic mullite, and mullite-precursors, such as kaolin and gibbsite in order to enhance the mechanical properties by increasing the mullite content. The change in the physical properties as well as the technological and mechanical behaviour were evaluated on the basis of the phase composition modifications. Introduction Porcelain stoneware tiles are primarily composed of clays, feldspars and quartz, heat-treated to form a mixture of glass and crystalline phases (new formed and residual ones), which are characterized by high mechanical, chemical and tribological properties, besides excellent aesthetic appearance. The current trend of producing ceramic tiles having larger and larger formats, for ever more severe applications, require to further enhance their mechanical behaviour, in terms of both flexural strength and fracture toughness. Many theories were proposed to explain the strength of porcelain ware, mainly based on the body mullite content [1,2], the existence of compressive or tensile stresses, caused by the thermal expansion coefficient differences [3], or the presence of dispersed strengthening particles [4,5]. However, only few papers in the literature deal with the effectiveness of these hyphotesis for porcelain stoneware bodies, leaving many opportunities to better understand the role of the microstructure and phase composition on the mechanical strength, fracture mechanisms and crack propagation [6, 7]. The microstructure of porcelain stoneware bodies, in terms of nature and amount of crystalline phases, can be achieved as a result of in-situ chemical transformations or by adding unreactive components as substitutes of the basic raw materials. This paper is focused on the possibility of improving the mechanical performances of porcelain stoneware tiles, through the addition to the starting powders of synthetic mullite and mullite-precursors (kaolin and gibbsite), in order to evaluate their strengthening and toughening role. For this purpose, the microstructural evolution, in terms of physical properties, as well as the mechanical strength and the fracture behaviour of the products were evaluated. Materials and Methods A typical industrial porcelain stoneware body (B) was modified adding mullite (M), kaolin (K) and gibbsite (G) in partial replacement of quartz. The addition amounts were 3-6-12 % for mullite and gibbsite, 5-10-20% for kaolin (Table 1). The production process was simulated at a laboratory scale by wet grinding, pelletization and humidification with 5-6 % water. Tiles (110 x 55 x 5 mm 3 ) were pressed at 40 MPa, dried at 105±5°C and fired in a roller kiln, with an industrial thermal-like cycle of 51 minutes, from cold to cold, at a maximum temperature of 1220°C. Key Engineering Materials Online: 2004-05-15 ISSN: 1662-9795, Vols. 264-268, pp 1491-1494 doi:10.4028/www.scientific.net/KEM.264-268.1491


Key Engineering Materials | 2004

Stain Resistance of Porcelain Stoneware Tiles: The Influence of Microstructure

Michele Dondi; Guia Guarini; M. Raimondo; E.R. Almendra; P.M.T. Cavalcante

This work deals with the appraisal of the most important microstructural parameters influencing the stain resistance of polished porcelain stoneware tiles. The correlations between the stain resistance on one side and bulk or surface characteristics on the other side were evaluated through a statistical approach, which provided a previsional model of the staining behaviour of tiles, based on the surface roughness as well as the pore amount, size and morphology.

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Michele Dondi

National Research Council

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Guia Guarini

National Research Council

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Chiara Zanelli

National Research Council

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Cesare Melandri

National Research Council

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P.M.T. Cavalcante

Federal University of Rio de Janeiro

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P.M: Tenorio Cavalcante

Federal University of Rio de Janeiro

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