Symposium CM
Science and Technology for Silicate Ceramics


Session CM-1 - Smart Silicate Ceramics

CM-1:IL01  Functionalised Exposed Building Materials
D.M. TOBALDI1, L. GRAZIANI2, B FIGUEIREDO3, M.N. CAPELA1, R. SILVA3, L. HENNETIER4, V ABRANTES3, P. FERREIRA5, M.P. SEABRA1, E. QUAGLIARINI2, J.A. LABRINCHA1, 1Department of Materials and Ceramics Engineering/CICECO - Aveiro Institute of Materials, University of Aveiro, Campus Universitário de Santiago, Aveiro, Portugal; 2Polytechnic University of Marche, Department of Civil and Building Engineering and Architecture, Ancona, Italy; 3Graphenest, S.A., Lugar da Estação, Edificio Vouga Park, Paradela do Vouga, Portugal; 4Technological Center for Ceramic and Glass Industries, CTCV, Coimbra, Portugal; 5RECER, Indústria de Revestimentos Cerâmicos, S.A., Oliveira do Bairro, Portugal

Traditional ceramic tiles are experiencing a new renaissance, this leading to an expected market value of >136 billion USD by 2020. Consequently, the interest in ceramic tiles is predicted to increase in places like hospitals, laboratories and residential buildings. This raised industrial concern about those technologies that are able to provide extra properties to the surface of silicate based ceramic materials. Indeed, they should be able to “interact” with the environment, so to become an active element contributing to energetic sustainability. In this work, we have functionalised the surface of commercial (glazed) ceramic tiles, aiming to give them additional functionalities. A TiO2 layer was added to give the material self-cleaning and photocatalytic abilities (liquid-solid phase photocatalysis and water contact angle, plus proper gas-solid phase photocatalysis), and biofouling property. Furthermore, high wear resistance was also attempted to be granted, to improve the durability of the material. A graphene layer was deposited by spray-coating on the surface of the material giving it the ability to conduct electricity and heat. This will unlock an important feature on the design of new and more efficient heated floors as well as on the generation of new ceramic heat pads.

CM-1:IL02  Energy Efficient Manufacturing of Ceramic Wall Tiles With and Without Functionality
F. KARA, Department of Materials Science and Engineering, Anadolu University, Eskisehir, Turkey

Ceramic tile manufacturing is an energy intensive process, energy cost being about 30% of the total manufacturing cost. Thus, there is a great need to reduce the energy consumption and associated CO2 emission in the tile industry. Although one obvious route would be to reduce firing temperatures with associated incremental improvement, different approaches are needed to have substantial impact on energy saving and geopolymerisation can be one of the answers to this. This is due to the requirement of much lower temperatures (25-150°C) to produce geopolymer materials compared to ceramic tiles which requires temperatures over 1100°C. Geopolymers are a kind of inorganic polymers typically formed by reaction between a solid aluminosilicate and sodium silicate solution under highly alkaline conditions. These materials are energy efficient ceramic-like materials which form and harden at ambient temperatures. In this presentation, an energy efficient manufacturing process for ceramic wall tile production will be proposed by utilizing the geopolymer technology. Mention will also be made how this technology could be viable to introduce certain functionalities to the tiles.

CM-1:IL03  Enhancing Silicate Ceramics with Photocatalytic Activity
A. SEVER SKAPIN, E. ŠVARA FABJAN, N. ROZMAN, L. ŠKRLEP, P. NADRAH, National Building and Civil Engineering Institute of Slovenia, Ljubljana, Slovenia

Modification of silicate ceramics with new materials introduces new properties and functionalities. Photocatalytic activity represents ability of the material to clean itself and its surroundings using light and can be used for water and air purification. With careful control of TiO2 properties, we have developed a photocatalyst showing high activity both in the UV and visible light spectrum. Photocatalysis on TiO2 is non-selective, which might not be advantageous. Therefore we have developed core@shell material TiO2@mesoporous SiO2, which showed fast preferential degradation of model pollutants even in the presence of abundant concentration of macromolecular natural organic matter. However, not all organic material surrounding TiO2 is a pollutant, i.e. pigments. To protect those compounds from photocatalytic degradation, we developed a SiO2-based protective shell, which forms a core@shell material with the pigment molecules at the core protected from the degradation.

CM-1:IL04  Effect of Firing Temperature on the Photocatalytic Activity of Ceramic Glazes
M. SCARPATO, A.M. BERNARDIN, Ceramic Materials Group, UNESC, Criciúma, Santa Catarina, Brazil

Photocatalytic glazes were developed by adding TiO2 in anatase form into commercial ceramic frits, the glazes were coated by spraying on enameled ceramic tiles and then undergoing a heat treatment between 800 and 1000 °C. The tiles with the TiO2 glaze were characterized by SEM and XRD, their wettability was determined by measuring the contact angle with water and their photocatalytic activity was determined by the degradation of methylene blue in contact with the coated tiles under UV irradiation. The microstructural analysis (SEM) showed that the TiO2 particles are properly dispersed in the glass matrix. The XRD analysis shows that from 850 °C the anatase particles are converted into rutile, causing loss of photocatalytic activity of the tiles. Under optimized conditions the anatase glaze yields 50% degradation of methylene blue dye at the end of 11 h of irradiation, with a reaction rate of 0.1138 h-1. Thus, the glazed tiles with TiO2 are a very interesting alternative to obtain self-cleaning surfaces.

CM-1:IL05  Development and Characterization of Multifunctional Coatings: Scratch Resistant Superhydrophobic Surfaces
R. TAURINO, F. BONDIOLI, Dipartimento di Ingegneria e Architettura, Università di Parma, Parma, Italy; M. MESSORI, M. CANNIO, Dipartimento di Ingegneria Enzo Ferrari, Università di Modena e Reggio Emilia, Modena, Italy; D.R. BOCCACCINI, G. MORINI, Tecnoitalia, Sassuolo, Italy

The development of easy-to-clean and self-cleaning surfaces is one of the most important outcomes of nanotechnology since its early beginnings. Even though a number of methods has been reported in literature, it has to be noted that many of them are not feasible for large-area applications. Moreover, another crucial limitation besides large-area applications is the scarce scratch resistance of common superhydrophobic surfaces. In this work, the authors evaluated the possibility to prepare multifunctional surface through layer-by-layer deposition of organic-inorganic hybrids sol-gel films, tailoring surface roughness and hydrophobicity. Superhydrophobic surfaces with contact angles higher than 150° and low hysteresis values, due to the presence of random irregular and fractal surfaces, were obtained. Both hydrophobic and oleophic properties were achieved after the application of nanostructured organic–inorganic hybrid coating based on a PFPE oligomer. Spray was employed since it present the advantage of preparing coatings with minimum wastage of precursor solution. One more time, saving and easy-to-handle method is the drop–on-demand jetting. Our preliminary results showed that we can create a surface with uniform macroscopic inorganic microstructure and hydrophobic properties.

CM-1:IL06  Transparent Titania-based Thin Films with Silicate Binder for Self-cleaning and Photocatalytic Applications
U. LAVRENVIC STANGAR1, 2, N. VODIŠEK2, A. ŠULIGOJ1, 3, 1University of Ljubljana, Faculty of Chemistry and Chemical Technology, Ljubljana, Slovenia; 2University of Nova Gorica, Nova Gorica, Slovenia; 3National Institute of Chemistry, Ljubljana, Slovenia

Photocatalytic TiO2 coatings are still one of the hot topics in catalysis research and application. Transparent titania-based thin films were prepared by wet chemistry routes. Considerable improvement of mechanical stability was achieved by modifying TiO2 with a wider band-gap semiconductor, ZrO2. For further improvement of optical properties and better adhesion of the films on mineral supports, a silicate binder was added to the mixture of metal alkoxide precursors in the sol-gel processing. Various composites in thin film form were deposited on glass and plastic substrates as transparent self-cleaning surfaces. They all have in common low-temperature synthesis route and silicate ceramic component. Samples with moderate addition of zirconia (5-10 mol%) are found to represent a good compromise between photocatalytic activity and durability of the coatings. Some results of the national on-going project “Thermo- and photo-active coatings for windows”, financed by the Slovenian Research Agency and M SORA d.d., will be presented as well.
Reference: N. Vodišek, K. Ramanujachary, V. Brezova, U. Lavrenčič Štangar: Transaprent titania-zirconia-silica thin films for self-cleaning and photocatalytic applications, Catalysis Today 287 (2017) 142-147.

CM-1:L07  Eco-friendly Self-cooling System of Porous Silicate Plates by Evaporation of Absorbed Water
HIROAKI KATSUKI, EUN-KYOUNG CHOI, WON-JUN LEE, UNG-SOO KIM, KWANG-TAEK HWANG, WOO-SEOK CHO, SRIDHAR KOMARNENI, Korea Institute of Ceramic Engineering & Technology; The Pennsylvania State University, USA

Porous silicate ceramic plates were prepared from clay and charcoal powder,and their porous properties, water absorption and the cooling effect of porous plates were investigated to produce eco-friendly porous ceramics for self-cooling system by the evaporation of absorbed water. Porous properties were dependent on the particle size of charcoal powder as pore forming additives and the firing temperature, and total pore volume, average pore size and porosity, which were 0.10 – 0.24 cc/g, 0.8 – 2.6 micrometer and 20.9 – 38.2 % at 1100 degree C. Cooling temperature difference of flowing air parallel to surface of porous ceramic plates fired at 1100 degree C was 3.5 – 3.6 degree C at 26 degree C and 60% of relative humidity in a test box. Cooling temperature difference was dependent on the relative humidity, temperature of the flowing air, the number of porous plates and the distance between porous plates. A simple and eco-friendly cooling system using porous ceramic plates fired from clay and charcoal powder was proposed. Furthermore, porous silicate plates were prepared from alumina powder with different particle sizes and bentonite clay, and their porous properties and the self-cooling effect were investigated.

Session CM-2 - Green Silicate Ceramics

CM-2:IL01  Valorization of Industrial Wastes in Green Ceramic Products
RUI M. NOVAIS, L. BURUBERRI, J. CARVALHEIRAS, J. CARNEIRO, M. SAELI, M.P. SEABRA, J.A. LABRINCHA, Department of Materials and Ceramic Engineering / CICECO-Aveiro Institute of Materials, University of Aveiro, Campus Universitário de Santiago, Aveiro, Portugal

This contribution reports the valorization of industrial wastes as major components of distinct ceramic products. Metal-rich sludges generated from plating and galvanizing processes (e.g. steel wiredrawing, Cr-galvanizing, Al-anodizing), fines or sludge from ores extraction/treatment (red mud or bauxite residue, marble-sawing/cutting sludge), sludge and dregs from the recovery circuit of chemical reagents and from the wastewater treatment, as well as fly ash from the cogeneration of energy, all them generated by the cellulose industry. Three distinct valorization ways were explored, namely production of ceramic pigments, Portland and belite-based clinkers, and porous geopolymers for environmental applications. In such way we explore massive but inexpensive products, as well as technical/advanced solutions, with higher value-added, as targets for wastes recycling.

CM-2:IL02  Porcelain Stoneware Tiles Above and Beyond Innovation: a Break with Tradition
E. RAMBALDI, Centro Ceramico, Bologna, Italy

Since 90s porcelain stonewares are the most performing ceramic tiles both for their technical and aesthetic characteristics that make them suitable for multiple environments. In the last years, this product has been object of a rapid evolution in terms of functionality and technological process and, nowadays, porcelain stoneware tiles are already marketed with characteristics and performances that go far beyond traditional uses. Traditional classifications in terms of surface finishing (glazed or unglazed tiles), destination use (indoor or outdoor, floor or wall tiles) would be overcome without considering the innovations. The driver of these innovations, such as photovoltaic, photocatalysis, high reflectance coating, is the sustainability. Sustainability is the driver also for technological innovations (pressing machines, kilns, digital printing) that allowed the production of high quality ceramic tiles in several sizes, from the traditional 30x30 cm till the largest format 320 cm x 160 cm and with thicknesses from 3 mm till 3 cm. This presentation focuses on the most relevant innovations on porcelain stoneware tiles in the last 20 years and would provide a scenario, in terms of sustainability (social, environmental and economic) impact, for the most promising innovations.

CM-2:IL03  Synthesizing Building Ceramics with High Crystallinity and Improved Properties from High Amounts of Industrial Wastes 
A. KARAMANOV, E. KARAMANOVA, G. AVDEEV, S. ATANASOVA-VLADIMIROVA, Institute of Physical Chemistry “Acad. Rostislaw Kaishew”, Bulgarian Academy of Sciences, Sofia, Bulgaria

A new type of building ceramics, containing no traditional fluxes and huge amount of inorganic industrial residues (for examples blast furnace slag, bottom ashes from municipal solid waste incinerator or fayalite copper flotation waste) is discussed. The chemical and phase compositions of these materials are very different from those of the common building ceramics; practically they are comparable to ones of some glass-ceramics from industrial wastes, which however are produced at significantly higher cost price. Because of their specific compositions, the studied ceramic batches are characterised by a relatively narrow sintering interval and intensive phase formation during holding and cooling steps of the production cycle. These specific futures are highlighted by complex dilatometry, DTA-TG, pycnometery, XRD and SEM-EDS studies. In general, the new ceramics are characterized by an enhanced crystallinity and fine-crystalline anorthite or/and pyroxene structures, which leads to improved mechanical properties. It is also shown that the peculiarities of the processes of densification and crystallisation, as well as the final phase compositions and morphologies of the studied compositions mainly depend by their position in the CaO-MgO (FeO) - Al2O3-SiO2 phase diagram.

CM-2:IL04  Waste Recycling in Clay Bricks
C.M.F. VIEIRA1, L. FONSECA AMARAL1, S.N. MONTEIRO2, 1State University of the Northern Rio de Janeiro, UENF, Advanced Materials Laboratory, LAMAV, Campos dos Goytacazes, RJ, Brazil; 2Military Institute of Engineering, IME, Department of Materials Science, Praia Vermelha, Urca, RJ, Rio de Janeiro, RJ, Brazil

The steel-making industrial sector, for example, generates a wide variety of solid wastes, predominantly composed by slag, powder, sludge and scrap. The need to find a correct environmental alternative to recycle a steel making wastes as well as the possibility to bring some technical advantageous to clay bricks for civil construction were the reason for this paper. This work has as its objective to evaluate the effect of incorporation of 5 wt.% of blast furnace sludge in the physical and mechanical properties of bricks produced in industrial scale. The atmospheric emissions of particulate material, nitrogen oxide and sulfur oxide were monitored beyond environmental tests of gross weight, leaching and solution. The results indicated that the waste is predominantly composed of iron oxides, coke fines, calcite and quartz. During the firing stage the waste can contribute significantly to save energy. Additionally the blast furnace sludge did not change the evaluated physical and mechanical properties of the clayey ceramic. The environmental tests showed that the investigated waste practically does not change the leaching and solution parameters of the ceramic and also it brings benefit as the reduction of the particulate material due to the decrease of the combustible consumption.

CM-2:IL07  Green Silicate Ceramics Based on Agro-residues
L. BARBIERI2, F. ANDREOLA1, R.D. FARIAS2, C. MARTÍNEZ GARCÍA2, I. LANCELLOTTI1, T. COTES PALOMINO2, 1Department of Engineering “Enzo Ferrari”, University of Modena and Reggio Emilia, Modena, Italy; 2Department of Chemical, Environmental and Material Engineering, High Polytechnic School of Linares, University of Jaen, Linares Scientific and Technological Campus, Linares, Spain

Agro-residues are very important as regards amounts produced and sector of recovery which involve both traditional fields such as production of feed for livestock and pet animals, cosmetic and pharmaceutical industry, fertilizers, food ingredients, biofuels, and innovative studies related to paper, foams for construction and industrial clothing sectors, tyres, ceramic pigments and deflocculants, activating solutions for the geopolimerization, lightweight aggregates for agronomic use. Each type of agro-residue often contains a lot of high added-value substances, for instance not only organic matter suitable as energetic support in the ceramic firing phase and pore forming agent, but also compounds acting as substituted for natural minerals (silica, quartz, etc.) and Critical Raw Materials such as Phosphorous. In this work it will be show the characterization of sawdust, grape and cherries seeds, sugarcane and rice husk ash, brewery sludge, together with local clays and other recovery raw material such as cattle bone ash and glass cullet, their tailoring in new green silicatic materials for building (bricks, pigments), additives (deflocculants) and agronomic (lightweight aggregates, glass and glass-ceramics fertilizers) sectors, their characterization and applications.

CM-2:L08  High-content Waste-based Bodies for Porcelain Stoneware Tiles: Technological Profiling
R. SOLDATI, C. ZANELLI, G. GUARINI, M. DONDI, CNR-ISTEC, Faenza, Italy; E. RAMBALDI, M.C. BIGNOZZI, Centro Ceramico, Bologna, Italy

Valorization of residues as raw materials in the manufacture of porcelain stoneware slabs is getting a growing interest in the literature, where a wide range of residues have been proposed as raw materials for tiles with promising results in terms of base properties. However, drawbacks arose about technological behavior of waste-bearing bodies and actual cases of transfer to the tile-making industry seem to be limited to cannibalization of residues of the ceramic process itself. In this work a dozen raw materials, mostly glasses, ashes and sludges, were characterized (chemical and phase composition, particle size distribution, thermal properties) and introduced as fluxes in replacement of feldspathic raw materials in a standard porcelain stoneware batch, reaching waste contents up to 70%. Blends always underwent a complete laboratory simulation of the industrial tile-making process in order to test their technological behaviors in milling, pressing and firing stages. Every waste has been classified through a technological profile that summarizes preliminary treatments needed and compositional features, and effects on grindability, compressibility and sintering by means of variation indexes based on particle size distribution, bulk density, firing shrinkage and water absorption.

Session CM-3 - Coating and Decoration of Silicate Ceramics

CM-3:IL01  Viscous Flow Sintering in Ceramic Glaze and Body Compositions
J.L. AMOROS, A. MORENO, E. BLASCO, Instituto de Tecnología Cerámica (ITC). Asociación de Investigación de las Industrias Cerámicas (AICE),Universitat Jaume I, Castellón, Spain

Viscous flow is the main sintering mechanism in ceramic glazes and bodies. The microstructural changes that occur in the sintering of these materials include continuous evolution of apparent and closed pore shape, size, and volume and of the relationship between apparent and total porosity, which determines the material’s final porosity. Final porosity is probably one of the major glaze and body characteristics as it, in turn, determines many of their performance properties. This study examines how porosity develops during sintering, characterising apparent porosity by mercury porosimetry (pore volume and size) and scanning electron microscopy (pore shape) and closed porosity by optical and electron microscopy and image analysis (pore volume, size, and shape). Notable growth of the larger pores was observed during sintering, associated with reordering of the rigid particles (crystals) by viscous flow of the melt: a) in materials (glazes and bodies) whose unfired microstructure was excessively heterogeneous (very wide pore and particle size distribution) and b) in glazes with abundant surface devitrification. The occurrence of this phenomenon determined, under optimum firing conditions, the final porosity of the material.

CM-3:IL02  Influence of Printing Parameters on Optical Properties of Ink-jet Ceramic Decoration
C. FERRARI, C. SILIGARDI, Department of Engineering “Enzo Ferrari”, University of Modena and Reggio Emilia, Modena, Italy

In the last years, ink-jet printing use is widely spread in ceramic industry. The particular difference in décor deposition, if compared with traditional ceramic decoration, can provide a wide range of different effects which are deeply appreciated. With respect to traditional decoration systems, the difference in thickness of decoration and nature of materials applied imply also an innovative color perception which should be better understood. This work is aimed to explore the effect of both different inks, white and colored, organic solvent and water based onto an engobed substrate. Moreover two different methods of décor application, greyscale and binary, will be investigated. Among traditional characterizations, a particular attention will be paid to color perception and spectral reflectivity of produced samples. These properties will be useful to provide suggestions on the final use of the different products and methods considering the destination use of the tiles.

CM-3:IL04  Improvement of Colour Quality and Reduction of Defects in the Ink jet-printing Technology for Ceramic Tiles Production: A Design of Experiments Study
M. MONTORSI, Department of Science and Methods for Engineering, University of Modena and Reggio Emilia, Reggio Emilia, Italy

The effect of different process parameters on the color and defects of tiles produced by ink-jet printing technology have been studied by using the Design of Experiment approach. The rational planning of the experiments allowed the obtainment of objective conclusions based on the statistical analysis of the data. Particularly, correlations between the process parameters and the quality of decorated tiles in terms of color and presence of surface defects were extensively investigated. Microstructural analysis was used to explain the results derived by the statistical analysis of the data leading to deeper insight in the structural features and mechanisms correlated to the final properties of the tiles. The study supplied an efficient way to control the final quality of the decorated tiles satisfying the standards required by the market demand.

CM-3:L05  Impact of Alkali Metal Oxygens on Structure and Properties of Ceramic Glazes
J. PARTYKA, K. PASIUT, M. LESNIAK, M. BUCKO, AGH University of Science and Technology, Krakow, Poland

In the scientific literature, regarding the influence of alkali metal oxides (sodium and potassium) on properties of glass-ceramic materials, the prevailing view is, that their functionality is almost identical. Due to this fact, in the Seger formulas, summary molar content of these alkali oxides are very often described as R2O where R = Na, K or simple KNaO which means a blend of sodium and potassium in any proportion. As well as, potassium has the same advantages and disadvantages as sodium. The third alkali metal oxide, Li2O is considered to be the strongest flux with a very low coefficient of thermal expansion. On the other hand, in his book "Glaze Chemistry" Hamilton claims that lithium oxide produces the same effect as sodium and potassium oxides. This presentation shows results of the influence of these alkali metal oxides on the structure of the glassy phase in glass-ceramic composite materials. Additionally, the presentation shows some results of selected physicochemical parameters of glass-ceramic materials from SiO2-Al2O3-CaO-MgO-R2O in the presence of various alkali metal oxides (R = Na, K, Li) and different molar ratio SiO2/Al2O3.
This research work has been carried out thanks to financing in the framework of NCBR programe No. N N508 477734.

Session CM-4 - Innovative Processing in Silicate Ceramics

CM-4:IL01  Chemical Tempering of Porcelain Tiles
D. HOTZA1, M. DAL BO2, 1Department of Chemical Engineering (EQA), Federal University of Santa Catarina (UFSC), Florianópolis, SC, Brazil; 2Federal Institute of Education, Science and Technology of Santa Catarina (IFSC), Campus Criciúma, Criciúma, SC, Brazil

Chemical tempering is an effective technique used to improve the mechanical strength normally applied to glasses. This process involves ion exchange of ions in the glassy phase, which are replaced by ions contained in a molten salt where the vitreous part is immersed. In this work, chemical tempering was adapted for strengthening porcelain tiles. Compared to non-treated samples, an increase of up to 74% in the flexural strength (54.5 MPa) of porcelain tiles was obtained, corresponding to a chemical treatment at 360 °C during 5.5 h. A similar result (52.1 MPa, 66% increase) was reached after a chemical treatment at 480 °C for 1 h. According to the analysis of variance, it was possible to determine the chemical treatment temperature as the variable that most influenced the flexural strength. Moreover, the interaction between the temperature and time of chemical treatment also played a significant role. Microstructural and chemical analysis confirmed the cation exchange between Na+ ions, initially present in the porcelain tile surface, by K+ ions present in the molten KNO3 bath. A concentration profile of Na and K elements in the porcelain cross section showed that the cation exchange occurred up to a depth of 200 mm from the surface of porcelain tiles. This behavior is in agreement with the tensile profile generally found in the chemical tempering of flat glasses. Thus, this work opens many research fronts regarding the application of chemical tempering in the porcelain tiles manufacture. Moreover, an increase of flexural strength can assist in the reduction of material thickness, leading to economic and environmental gains.

CM-4:IL05  Study of the Thermal Behavior and VOC Emission of Digital Inks and Glazes for Ceramic Tiles
P. ZANNINI, G. FERRARI, University of Modena and Reggio Emilia, Chemical and Geological Science Department, Modena, Italy

The decoration of ceramic tiles was, recently, deeply changed and increased by the introduction of Ink Jet printers, that utilize new inks, suitable to obtain the wished effects. These new inks were projected with a 25-50 % of solid ceramic pigment, in the propter grain size distribution, and a liquid, mostly organic, vehicle, according typically to its rheological features. Very few is known about its combustion properties, when fired together with the tile into the kiln. Nearly a hundred samples of different industrial Inks, across ten years, were collected from different producers, and examined by thermal analyses at 5 and 50°C min-1, by C-H-N-S analysis and by combustion into a tubular electric lab. kiln, collecting the emitted vapors and analyzing them with propter GC-MS techniques. The results will be discussed, trying to find a comparison among the decoration technique ( from Silk Printing, to rotative serigraphy, though Rotocolor™, to the different stages of Digital Inks, to end at the Water Based inks ), to assess the quality and the quantity of emissions .

CM-4:IL06  New Advances on Functional Porcelain Technology
NOBUAKI KAMOCHI, K. NISHIYAMA, H. KATSUKI, Saga Ceramics Research Laboratory, Arita-machi, Saga, Japan 

Basically porcelain bodies exhibit pyroplasiticity when they are fired. The control of pyroplastic deformation is very important issue since it affects the shape of product. The influence of talc addition on the pyroplastic deformation of alumina-strengthened porcelain was investigated and compared with the traditional porcelain. In the traditional porcelain, the quartz grains are distributed separately from each other in the sintered body, which enables mobility of the quartz grains in the presence of an excess glass, ultimately leading to pyroplastic deformation during the firing process. Hence, the shape of a traditional porcelain product is easily deformed. The presence of talc contributed to the crystallization of the cordierite phase during the firing process, and the resulting cordierite phases formed complicated filler structures that were hard to move even at an increased amount of the glass phase or lowered viscosity. The porcelain samples made with the addition of talc showed an unprecedented pyroplastic deformation characteristic with almost no changes in the pyroplastic deformation index value during further firing at over 100°C after the water absorption reached almost zero.

CM-4:L07  Densification of Porcelain Stoneware Tiles: A Simplified Model Based on Technological Properties 

Porcelain stoneware tiles are sintered by fast firing, through partial vitrification and viscous flow of an abundant liquid phase. Firing schedules are designed to achieve a very low water absorption (~0.1%) and controlled shrinkage, for maximum temperatures around 1200°C. By this way, the gresification model predicts to get the highest bulk density, which nevertheless depends on the closed porosity left during sintering. However, it may happen that the minimum water absorption is reached only after a shrinkage and bulk density turnaround, implying that a significant amount of closed porosity developed. A deviation from the expected behavior can occur particularly in case of strong fluxes, like those containing large amounts of alkaline-earth oxides or boron compounds. In order to have a facile check on sintering based on easily available technological properties, the classic gresification sketch has been revisited, by proposing a simplified model to estimate the residual porosity in porcelain stoneware by matching water absorption and bulk density.

CM-4:L08  Phase Transformations and Related Liquid Phase Physical Properties: Evolution During the Viscous Flow Sintering in Porcelain Stoneware Tiles
S. CONTE1, C. ZANELLI1, M. ADIT2, G. CRUCIANI2, M. DONDI1, 1CNR-ISTEC, Faenza Italy; 2Department of Physics and Earth Sciences, University of Ferrara, Italy

The viscous flow sintering of porcelain stoneware tiles involves a complex evolution of both phase composition and chemistry of the liquid phase. The formation of an abundant liquid phase during sintering is a process that must be kept under strict control to achieve the desired properties of final products and prevent defects induced by pyroplasticity. This is particularly true for the production of large tiles, which requires uniform densification and minimal deformations at high temperature. In this work, five body formulations (mainly sodic or potassic and mixed Na-K), consisting of a mixture of ball clay, quartz and feldspars, were investigated. Samples were characterized by isothermal and constant rate optical TDA (hot stage microscope) and quantitative XRPD (Rietveld method), on quenched specimens. In the initial stage of sintering, the main transformations are the breakdown of clay minerals with the formation of amorphous components and mullite. In the intermediate stage the sintering is governed by the abundant liquid phase and by its physical properties. In the final stage a decreasing of densification rate is contrasted by a coarsening mechanism; a crucial role is probably played by changes in the solubility of solids and gases in the liquid phase.

Session CM-5 - Geopolymers

CM-5:IL01  Working Mechanisms of Superplasticizers on Alkali-Activated Cements
M. PALACIOS1, P. BOWEN2, F. PUERTAS1, 1Eduardo Torroja Institute for Construction Science (IETcc-CSIC), Madrid, Spain; 2École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland

Concrete is essential in our society for housing and infrastructure. Because of the large amount of concrete and cement yearly consumed, the cement industry finally accounts for 8-9% of CO2 worldwide emissions. Alkali-activated materials have been deeply studied as an alternative and ecoefficient cement. These cements are produced by mixing an aluminosilicate with a highly alkaline solution. Concrete produced with these cements have proven to have suitable engineering properties and high durability against chemical attack. However, their poor rheological properties represents one of the barriers for the implementation of these alternative cements, mainly when sodium silicate is used as an activator. This paper gives an overview of the impact of superplasticizers with different molecular structures on the rheological properties of alkali-activated slag cements. Results have shown the incompatibility of most superplasticizers with these alternative cements. Furthermore, the mechanism of action of the working admixtures have been resolved by a combination of experimental and modeling techniques. In particular, the obtained results concluded that the dispersion mechanism is dominated by the steric repulsion, an important design criterion for improving the rheological behaviour.

CM-5:L03  Thermal Resistant Alkali-activated Materials Based on Various Aluminosilicate Sources 
M. FRICHETEAU, A. GHARZOUNI, S. ROSSIGNOL, Science des Procédés Céramiques et de Traitements de Surface (SPCTS), Limoges Cedex, France

Under necessity to develop new fire resistant and durable construction materials geopolymer materials appear as promising candidates. These binders have garnered increasing interest over the last decades because of their high working performances, wide range of applications and low environmental impact. This study aims to formulate thermally resistant geopolymer compositions. To achieve this objective, different raw materials were used such as metakaolins and argillite calcined with different processes and temperatures (flash and furnace calcinations). Moreover, several alkaline silicate sources in different forms (solution and powder) have been used. In order to increase the thermal resistance, different fillers such as calcined-clay or sand were used. The thermal resistance tests at 850 °C and thermal shocks have demonstrated the possibility to formulate thermal resistant argillite based samples. To optimize the thermal resistance the use of mineral additive was evidenced to limit the apparition of viscous flow and to improve the mechanical properties.

CM-5:L04  Mechanical and Thermal Properties of Fly Ash Based Geopolymer Composites
P. TIMAKUL, P. HENPRASIRTTAE, DUANGDUEN ATONG, PAVADEE AUNGKAVATTANA, National Metal and Materials Technology Center and National Nanotechnology Center, Klong Luang, Pathumthani, Thailand

Geopolymers are alkali-activated aluminosilicate materials which have desirable mechanical strength and thermal properties for applications such as construction and refractory. In this work, the major materials used to synthesize geopolymer composites were fly ash and basalt fibers in the ratio of 90:10 wt% (fly ash to basalt fibers). In order to dissolve alumino-silicate in raw materials, an alkali-activator was prepared by mixing sodium hydroxide and sodium silicate solutions by 2.5 : 1 mass ratio. In addition, Titanium dioxide (TiO2) 1-5 wt% was added to the mixture for exploring its effect on the compressive strength and the thermal shock resistance of the samples. The resulting geopolymers were cured at 50 C for 48 h and further cured at R.T. until aged 28 days. The XRD patterns composed of alumino-silicate from 20-40 degree (2 theta) with some crystalline patterns of anatase, calcium-silicate-hydrate, and other crystalline phases. Thermal shock resistance cycled from 800 C to R.T. declared that samples with 5 wt% TiO2 showed higher compressive strength than TiO2-free samples in every interval examined cycle. The retained compressive strength of 5 wt% TiO2 after 15 cycles of thermal shock test was 26 MPa which was higher than that without TiO2 samples (18 MPa).

CM-5:L05  Effect of Aluminum and Alkali Cation Earth Reactivity on Alkali-activated Materials Formation and Structure 
A. GHARZOUNI, L. OUAMARA, S. ROSSIGNOL, Science des Procédés Céramiques et de Traitements de Surface (SPCTS), Ecole Nationale Supérieure de Céramique Industrielle, Limoges, France; I. SOBRADOS, Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain

This study aims to determine the influence of aluminum and calcium availability from different aluminosilicate sources thermally treated at 750°C, on the formation, the structure and the working properties of the resulting alkali-activated materials. Despite their similar chemical composition, some differences in terms of aluminum coordination, amorphous phase and calcium availability were detected between the two studied aluminosilicate sources. Indeed, sediment sample exhibits higher reactive aluminum and lower reactive calcium compared to argillite sample. Moreover, FTIR spectroscopy has revealed that available calcium interacts with free silicon and aluminum and alkali cation in excess (sodium or potassium) leading to the formation of several networks (Si-O-Al and Si-O-Ca bonds). For both aluminosilicates, the calcium content seems to be low to produce C-S-H hydrated phases. It was also demonstrated that the low availability of aluminum in addition to the high availability of calcium favor the precipitation of secondary reaction products in the detriment of the geopolymer network. However, the higher availability of aluminum and the lower availability of calcium in presence of high alkaline conditions favor the polycondensation reaction.

CM-5:L06  Thermal Stability and Mechanical Properties of Wollastonite Reinforced Fly Ash-based Geopolymer
K. HEMRA, S. JIEMSIRILERS, Department of Materials Science, Faculty of Science, Chulalongkorn University, Bangkok, Thailand; P. AUNGKAVATTANA, National Nanotechnology Center, Bangkok, Thailand; T. KOBAYASHI, Department of Materials Science and Technology, Nagaoka University of Technology, Niigata, Japan

In this study, fly ash from Mae Moh power plant in the northern part of Thailand was used as raw material to prepare geopolymer. The geopolymer samples were prepared by mixing fly ash and alkaline solution with the solid to liquid ratio of 3:2 in weight ratio. The alkaline solution was prepared by mixing potassium hydroxide (6 M) and potassium silicate by 1:1 in weight. Wollastonite fiber has high thermal shock resistance and low coefficient of thermal expansion. It was added into fly ash-based geopolymers ranging from 5-30 wt.% to enhance geopolymer properties. Mechanical strength and thermal stability of geopolymer composite increased with an increasing of wollastonite fiber. The compressive strength of fly ash-based geopolymer composites cured for 7 days at room temperature was 21 MPa which increased 21% with 30 wt.% wollastonite addition comparing to wollastonite free samples. XRD patterns of fly ash-based geopolymer composites showed an amorphous phase of geopolymeric gel at 2θ equals to 23-38°, and major phases of wollastonite, arcanite, magnesioferrite, calcite, anhydrite, calcium silicate and unreacted quartz. SEM micrographs showed dense geopolymer matrix combined with some unreacted fly ash particles, wollastonite fibers, reacted phases which corresponding to XRD results. The fly ash-based geopolymer composites were thermally tested for stability at 800-1000°C for 2 h. Fly ash-based geopolymer composites with high percentage of wollastonite fiber addition were presented good thermal stability at high temperature. Results found that 20 wt.% wollastonite addition can reduce cracking during shrinkage at elevated temperatures. FT-IR measurement and SEM were also studied for microstructure evaluation. In sum, results indicated that wollastonite reinforced fly ash-based geopolymer composites is promising to be used at high temperature applications.

CM-5:L07  Synthesis of Geopolymer Foams: Application in the Retention of Heavy Metals 
K. KHATIB, H. BENBAKRIM, M. EL AZHARI, Cadi Ayyad University, Marrakech, Morocco

Inorganic aluminosilicate polymers, in addition to the interest they present as cement whose production does not generate large quantities of greenhouse gases, offer great potential for application in the protection of the environment in their synthesis methods. The purpose of this work is to recover industrial waste, in particular fly ash, to synthesize a material that adsorbs heavy metals from wastewater. The structures and methods of synthesis of these materials as well as tests of their applications will be exploited in this study. In this study, geopolymer materials were developed from industrial waste (fly ash) using different parameters: Si / Al ratio, Si / Na ratio, liquid / solid ratio, in order to optimize the capacity of retention which depends on the intimate structure of the material. It is a geoplymer foam whose porosity has been controlled by introducing different amounts of hydrogen peroxide during the synthesis. The relatively simple synthesis method of this material and its capacity for retention of heavy metals make it a solution for the depollution of effluents loaded with heavy metals, in particular the rejects of the leather industries.

CM-5:IL09  Alkali Activated Green Building Materials - Selected Case Studies 
V. DUCMAN, Slovenian National Building and Civil Engineering Institute, Ljubljana, Slovenia

Alkali activated materials (AAM) are obtained trough the reaction of aluminosilicate materials, preferably waste, with alkali activation solutions what results in materials and products with properties comparable to ceramic or concrete. Beside research on replacing of cement based concrete with AAM there are also some others, niche applications. One of such are AAM foams which are formed at temperatures below 100 oC and possess properties similar to foamed glass or ceramics and could serve as thermally insulating building product. Foams with open or closed porosity, with a density below 0.3 g/cm3 and with satisfactory mechanical properties can be obtained. Another potential application is AAM as repair mortar where with a right combination of precursors and activators product fulfilling the requirements for structural and non structural repair mortars (EN 1504-3:2005) can be obtained. Application which could consume lot of waste is AA aggregate for concrete. Such aggregate can be obtained by granulation on a pelletization plate or by crushing oh hardened AAM and sieving into different fractions. So obtained aggregates have densities below 2000 kg/m3 what classify them into lightweight aggregates (EN 13055-1:2002).

CM-5:L10  Valorization of Biochar By-products into Alkali-activated Materials
R. FARGES, A. GHARZOUNI, S. ROSSIGNOL, SPCTS, UMR 7315, Limoges cedex, France; P. JEULIN, B. RAVIER, Etablissement MAILLOT, Vernouillet, France

BioConcrete project falls within an approach of Biolyse® process products valorization. This innovative process, environmentally friendly, is a way to thermally treat biomasses residues at low temperatures in a lack of oxygen without releasing suspended particulate matter, smokes and greenhouse gases leading to a solid residue called biochar. The aim of this work is to study the feasibility of the valorisation of the biochar by-product into alkali-activated materials. Four types of biochar by-products, produced from wheat straw, miscanthus and wood, under different pyrolysis conditions were studied. At first, the physical and chemical properties of biochar by-products were determined. Structural data were obtained by infrared spectroscopy (FTIR) and X-ray diffraction. Then a feasibility study of consolidated materials and foams was initiated. First results show that the chemical composition of biochar by-product is essentially composed of silicium, potassium and calcium. Differences are observed according to the type of biomass used to obtain biochar by-product. Alkali-activated binders were successfully synthesized from biochar by-products and different metakaolins. Furthermore, biochar by-product based alkali-activated foams were obtained using silica fume.

CM-5:L12  Effect of NaOH Concentration and Curing Time on Mechanical Properties and Microstructure of Geopolymer Prepared from Kaolin Processing Waste
S. PRASANPHAN, S. JIEMSIRILERS, Department of Materials Science, Faculty of Science, Chulalomgkorn University, Pathumwan, Bangkok, Thailand; T. KOBAYASHI, Department of Materials Science and Technology, Nagaoka University of Technology, Kamitomioka, Nagaoka, Niigata, Japan; A. WANNAGON, National Metal and Materials Technology Center, Thailand Science Park, Khlong Nueng, Khlong Luang, Pathum Thani, Thailand

Geopolymer samples were prepared from kaolin processing waste. Prior to use as raw materials for geopolymer, the kaolin processing waste was calcined at 700 ˚C for 1 hour. Geopolymer samples were synthesized by using 24 wt% alkali solution as alkali activator and cured at room temperature for 1-28 days. The alkali solution was prepared by Na2SiO3 solution mixed with NaOH solution in the range of 4-10 M. Geopolymer samples were formed by a hydraulic pressing machine at a pressure of about 20 MPa. The degree of geopolymerization of geopolymer with various NaOH concentrations was measured by DSC technique. Geopolymer samples were characterized using Instron mechanical tester, XRD, SEM, BET, and FTIR. The DSC results indicated that the reaction of geopolymerization increased with an increasing of NaOH concentration. Compressive strength of geopolymer at NaOH concentration of 10 M and curing time of 28 days was 26.98 MPa and 28.55 MPa, respectively, which increased approximately 18.42% and 38.40% compared with NaOH concentration of 4 M and curing time of 1 day. An increasing of amorphous phase and decreasing of intensities of disordered muscovite, mica and sannidine phases in geopolymer samples were identified by using XRD technique. SEM micrograph of geopolymer samples displays more geopolymeric gel and denser matrix with an increasing of NaOH concentration and curing time. The nitrogen adsorption and pores volume decreased with an increasing of NaOH concentration and curing time. FT-IR results revealed the broad band and the shift toward lower wavenumber of the Si-O-Si and Si-O-Al asymmetric stretching vibrations with an increasing of NaOH concentration and curing time. Synthesis of geopolymer using kaolin processing waste as raw material is a value added and environmentally friendly process.

CM-5:L13  Formation, Structure and Mechanical Properties of Alkali-activated Materials Based on COx Argillite 
C. DUPUY1, 2, A. GHARZOUNI2, N. TEXIER-MANDOKI1, X. BOURBON1, S. ROSSIGNOL2, 1Agence nationale pour la gestion des déchets radioactifs (Andra), Chatenay-Malabry Cedex, France; 2Science des Procédés Céramiques et des Traitements de Surface (SPCTS), Centre Européen de la Céramique, Limoges Cedex, France

If the construction of Cigéo, the French geological disposal for radioactive waste, is accepted; the digging of the facilities will lead to the excavation of a large amount of Callovo-Oxfordian (COx) argillite. The valorization of this raw material by alkaline activation is actually studied. For this, the COx argillite without and with thermal treatment at 750 °C with furnace and flash processes were investigated. These treatments lead mainly to dehydroxylation of clay minerals and decomposition of carbonate compounds. The feasibility of alkali-activated samples, based the different argillite samples and mixtures of them, was evaluated. Then, consolidated samples were characterized by FTIR, X-ray diffraction, thermal analysis and compressive strength measurement. It was demonstrated that the alkali activation is possible for all samples that contain at least 25 % of calcined argillite (both furnace of flash treatments). However, only samples without raw argillite evidence the formation of a geopolymer network and exhibit sufficient compressive strength. Last, the decomposition of the carbonate species (which produce free calcium and magnesium) is further studied. Indeed, the free earth alkaline cations lead to structural modification in the alkali-activated samples.

CM-5:IL16  NMR Investigations on Silicate Compounds
I. SOBRADOS, Instituto de Ciencia de Materiales de Madrid-Consejo Superior de Investigaciones Científicas. Madrid, Spain

Silicate and aluminosilicate minerals contain Si and Al in quite a lot of environments and structural units. Thanks to the high resolution of MAS NMR spectroscopy and the sensitivity of the isotropic chemical shift to local variations in the atomic environment, 29Si and 27Al MAS NMR spectra can be correlated with the structural units occurring in the various classes of silicate mineral structures. A brief introduction will be given to summarize the identification of silicate minerals based on their chemical shifts ranges [1]. The modern chemistry of silicates is highly broad and diverse, ranging from minerals to organometallic siloxanes and catalysts to microporous zeolites to mesoporous silica and hybrid materials; aluminosilicates play a significant role in many areas of basic and applied research, such as chemical catalysis, classical and advanced ceramic production, cement and concrete technology and geochemistry. This lecture will highlight the role that solid-state NMR plays characterizing both amorphous and crystalline aluminosilicate precursors and the structural features having influence in its chemical reactivity, to understand the mechanisms of material synthesis. Examples of advanced NMR spectroscopic characterization methods will be shown to study ceramic materials, thermal decomposition of minerals, intercalation reactions of clay minerals and to characterize the reactions products formed in alkaline activation reactions.
[1] Lippmaa el al. J. Am. Chem. Soc. (1980) 102, 4889

CM-5:IL17  Novel Perspectives in the Synthesis and Application of Aluminosilicate Matrix Composite Materials 
C. FERONE, G. ROVIELLO, L. RICCIOTTI, R. CIOFFI, Dipartimento di Ingegneria, Università di Napoli ‘Parthenope’, INSTM Research Group Napoli Parthenope, Napoli, Italy

An innovative method for the preparation of composites based on geopolymer aluminosilicate matrix and organic resins is reported. The materials were prepared through a simple and cost-effective synthetic approach consisting in the incorporation of the organic resin into a metakaolin geopolymeric suspension under mechanical stirring, when both polymerization reactions have been started but not completed yet. A simultaneous polycondensation reaction between organic and inorganic phases occurs resulting in a good interpenetration of the resin into the inorganic matrix up to micrometric level. The obtained samples showed significantly improved mechanical properties if compared to the neat geopolymer, along with good thermal stability and fire resistance. These properties make them optimal candidates for applications in the field of high performance materials: starting from structural roles such as reinforcement and repair of building structures (mortar and concrete manufacturing), to obtaining components with controlled porosity (by using suitable foaming agents) for the manufacturing of thermal and acoustic insulation panels. Finally, the possibility of using industrial byproducts as starting raw materials could make the final product cheaper and environmental friendly.

Cimtec 2018

Piva 03368230409
Phone +39 0546 22461 - Fax +39 0546 664138
Corso Mazzini 52 48018 - Faenza (RA) - Italy
Privacy Policy - Software Commercio Elettronico by