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Symposium CN
Geopolymers, Inorganic Polymers and Sustainable Materials

ABSTRACTS

CN-1:IL01  Advances in Understanding the Gel Structure of Geopolymers
B. Walkley, D. GEDDES, Department of Chemical and Biological Engineering, The University of Sheffield, Sheffield, UK

Alkali aluminosilicate ‘geopolymer’ gels are characterized by a three-dimensionally cross-linked, structurally disordered alkali aluminosilicate network. Geopolymers have received significant academic and commercial interest in recent years because of desirable technical and environmental characteristics, with applications in zeolite synthesis, in sol−gel processing, as low-cost refractories, as low-CO2 construction materials, in radioactive waste treatment, and in biomaterial and fibre composite applications. Using advanced solid-state nuclear magnetic resonance (SSNMR) spectroscopy, diffraction-based techniques and microscopy, we have recently proposed a new structural model of hydrous alkali aluminosilicate gels, in which charge-balancing extra-framework Al species are observed in geopolymers for the first time. This lecture will discuss these and other recent advances in understanding the nanostructure of geopolymer gels, and how these approaches can be exploited to control material performance for a variety of applications.


CN-1:IL02  How to Control the Porosity of Dense Geopolymer?
S. ROSSIGNOL, IRCER, University of Limoges, Limoges, France

This study focuses on geopolymer porosity control in order to device the selected applications. The synthesized materials have a defined range of porosity and impose its working properties, which are governed by its porous architecture but also by the nature of solid skeleton. Thus, various parameters, such as the precursor’s reactivity, the introduction of additives or the manufacturing process, govern the material formation. The nature of the precursors, such as the zeta potential, the amount of reactive aluminum in aluminosilicate source (NMR), the siliceous species present in solution (Raman), controls the reactive mixtures properties such as surface tension, viscosity and setting time. Moreover, in order to optimize the structure and microstructure some fillers can be introduced into the formulations. All of these data influence the reactive mixture affecting the porosity. Finally, a wide range of geopolymer materials were synthetized up to the TRL4 scale.


CN-1:IL03  Hybrid Cements: Processing and Structural Characterization
I. Garcia-Lodeiro, A. Palomo, A. Fernández-Jimenez, Eduardo Torroja Institute (Ietcc-CSIC), Madrid, Spain

The environmental problems posed by portland cement manufacture have prompted the scientific committee to seek more eco-efficient binders with the same technological features as OPC; hybrid cements are among such alternative materials. Hybrid alkaline cements are multi-component systems containing a high mineral addition content (such as fly ash (FA), metakaolin (MK) or  blast furnace slag (BFS)), low proportions of portland clinker (<30 %)  and moderately alkaline activators. The substantially lower amount of clinker needed to manufacture these binders than ordinary portland cement is both economically and ecologically beneficial. The present study explore basic principles about processing, strength development and the structural characterization on several hybrid cements, consisting of a number of industrial by-products and very low portland clinker contents.


CN-1:IL04  Effect of Dispersed Phases on the High-temperature Behavior of Alkali-activated Composites
M.C. Bignozzi, Dept. of Civil, Chemical, Environmental and Materials Engineering, University of Bologna, Bologna, Italy

Mix design is a key parameter for alkali activated materials in order to address their properties for desired applications. Carbon fly ash-based alkali activated materials have been intensively studied for their high temperature behavior and the results obtained so far are particularly promising. With the aim to improve their performances it is interesting to study if the addition of dispersed phase in the alkali-activated matrix may promote their use as passive fire protection system for steel structures and/or as high temperature resistant materials for applications in furnaces, coatings for reactors, etc. In this contribute, the effect of silica sand, alumina powders, expanded perlite as dispersed phases in carbon fly-ash geopolymer matrix is reported and discussed on the basis of the experimental results obtained by thermal and physical-mechanical characterizations. Indeed, the presence of such additions properly mixed in alkali activated mixes can be particularly useful to boost geopolymers towards new uses and applications.


CN-1:IL06  Utilization of Mine Tailings in Alkali Activated Materials
M. ILLIKAINEN, P. PERUMAL, Fibre and Particle Engineering Research Unit, University of Oulu, Oulu, Finland

Mine tailings are a major waste flow generated in the mining industry. Most of the tailings have limited practical use. Mine tailings have fine particle size and high specific surface area. The tailings consist of chemical elements interesting for cementitious materials. Because of the favourable physical and chemical properties, the use of tailings as precursors to alkali-activated materials is an increasing research area. Usually mine tailings contain minerals with low reactivity under alkaline conditions. Mineralogy is the most important factor defining the reactivity. In some cases, the reactivity can be enhanced by pre-treatment methods such as thermal or mechanical treatments. It has been found that the silicate mine tailings rich in phyllosilicates have the highest potential for alkali-activated materials. They also have the highest response to the mechanochemical or thermal pre-treatment before the alkali activation. There is a need to develop new safety methods to utilize and storage mine tailings instead of landfilling in tailings dams. Alkali-activated mine tailings could also find applications on-site as mine backfilling or construction materials.


CN-1:IL07  Cordierite and SiAlON Foams from the Thermal Treatment of Geopolymer-like Hardened Suspensions
A. Rincon1, H. Elsayed1, F. Dogrul2, P. RABELO mONICH1,2, E. Bernardo1, 1University of Padova, Dept. of Industrial Engineering, Padova, Italy; 2University of Trencin, FunGlass (Centre for Functional and Surface Functionalized Glass), Slovakia

Air may be easily incorporated by vigorous mechanical stirring, with the help of surfactants, of activated geopolymer-yielding suspensions. The cellular structure is stabilised by the viscosity increase caused by curing reactions, configuring an ‘inorganic gel casting’. The approach is so flexibile that it may be applied to mixtures embedding fillers, such as reactive γ-Al2O3 powders, playing a fundamental role upon ceramic conversion, at high temperatures. After successful development of mullite foams, the present study is dedicated to recent extensions to highly porous cordierite and SiAlON foams, obtained starting from Na-based geopolymer-yielding mixtures added with talc or carbon black, and fired in air (at 1200-1250 °C) or nitrogen (at 1500 °C), respectively. A key intermediate step is represented by the removal of Na+ ions from ‘green’ foams, by ion exchange in solution (0.1 M) of ammonium nitrate, before ceramization. The phase purity is conditioned, especially in the case of cordierite ceramics, by the length of the exchange treatment (24-120 h): in fact, sodium contaminations (for short exchange treatments) may lead to glass phase, compromising the thermal stability. We will show, however, the feasibility of direct ceramization of alkali free hardened suspensions, achieved by activation of metakaolin-based mixtures with ammonium and tetramethylammonium hydroxides. The new gels are effective in yielding phase pure cordierite as well as β/X-SiAlON with minor corundum impurity.


CN-1:IL08  A Different Approach for a Sustainable Binder: the Extraordinary Leuven Cement
Y. Pontikes, KU Leuven, Department of Materials Engineering, Leuven, Belgium

Cements today are calcia-rich. This holds true for most of the new clinkers developed as well. In the work herein we present a different binder that is Fe-rich. The name of this new binder is Extraordinary Leuven Cement. It is abbreviated as ELCE, suggesting that “elce”, an obsolete form of “else”, ie something different, is a possibility even for one of the most massively used materials today. The presentation starts with an analysis of the drives that led to these formulations and analyses the environmental impact of the new binder in comparison to other approaches. It continues with an overview of the raw materials and presents in detail the process, with the different unit operations, providing information on the production parameters, such as firing conditions, milling, additives, (…). It concludes with the two lines of binders that have been developed over the past years, one with OPC (blended) and the other one without. In addition to OPC, these formulations can also integrate other materials, namely ground granulated blast furnace slag, fly ash, calcined clays and more, thus, resemble to a great extent the family of blended cements in the market today. All in all, the work covers a wide span, from experimental results at both laboratory and pilot-plant scale, to computational simulations on the atomic structure of the precursors of ELCE. It closes with our approach for add-water-only mortar formulations and ultra-high strength concrete, and presents our upscaling mobile units that aim to demonstrate the easiness and robustness of the process.


CN-1:IL10  Mesoporous Geopolymers for Fire Resistant Insulating Panels
C. Leonelli1, E. Kamseu1, 2, 1Dipartimento di Ingegneria "Enzo Ferrari", Università degli Studi di Modena e Reggio Emilia, Modena, Italy; 2Laboratory of Materials, Local Materials Promotion Authority, MINRESI/MIPROMALO, Yaoundé, Cameroon

The porous and amorphous structure of inorganic polymer cements (IPC), often indicated as geopolymers, implies that flow in a thermal gradient take a very tortuous route consisting of interconnected polysialate particles. The effective thermal conductivity of such a material is strongly affected by its chemical composition as well as the presence of voids in the microstructure which are pockets or cells more or less spherical in shape. The microstructure of IPC is known to vary considerably with chemical composition, processing conditions, and addition of porogens as H2O2, or Al powder. Correcting the viscosity of the IPc pastes, a highly porous material with the fine pores homogeneously distributed in the matrix can be obtained, allowing this microstructure to be close to the ideal two phase structure. Two phase structure responds to the Maxwell–Eucken model 1. For the metakaolin based geopolymer, the bulk thermal conductivity decreased from 0.25 W m−1K−1 at ∼75 vol.% of porosity to 0.16 W m−1K−1for the porosity ∼90 vol.%. Additions of volcanic ash and rice husk ash was proposed to reduce the overall cost of the materials, whilst metabauxite and metatalc additions prevented the imperfections presented when the matrices are subjected to high temperature.


CN-1:IL11  Effect of the Chemical Admixtures on the Geopolymer Properties based on Glass Powder
T.M. Tognonvi, A. Balaguer Pascual, A. Tagnit-Hamou, K.P. Koba,  Department of Mathematics Physics Chemistry, University of Peleforo Gon Coulibaly, Korhogo, Cote d’Ivoire; Department of Civil Engineering, University of Sherbrooke, Sherbrooke Quebec, Canada; Department of applied geology, University of Jean Lorougnon Guede, Daloa, Cote d’Ivoire

Geopolymers are mineral binders obtained by alkaline activation of siliceous or aluminosilicate materials. They are considered, today, as potential alternative to Portland cement. Indeed, these binders develop physico-chemical properties similar or even superior to those of ordinary cement. Also, they are more environmentally friendly and develop better durability. However, their fresh state properties that govern the hardened properties of the material are difficult to control because of the great variability of the material sources (metakaolin, fly ash, blast furnace slag, etc.). Chemical admixtures, used for their dispersing power, are often incompatible with activated systems. This study aimed to evaluate the effect of different chemical admixtures on the workability of activated glass powder/metakaolin blend. Four chemical admixtures including polycarboxylate (PC), polyphosphonate (PP), polynaphthalenesulfonate (PNS) and lignosulfonate (LNS) -based superplasticizers were considered. Flow measurements were carried out on pastes containing 95 wt% glass powder and 5 wt% metakaolin. Only LNS and PNS were found to be effective in improving the paste workability. This allowed the optimization of metakaolin content up to 30 wt% in the activated material.


CN-1:L12  Large Scale Additive Manufacturing of Inorganic Geopolymer Components Using Binder Jetting
H. ELSAYED1, 2, F. Gobbin1, 3, M. Picicco1, 4, A. Italiano3, P. Colombo1,5, 1Department of Industrial Engineering, University of Padova, Padova, Italy; 2Refractories, Ceramics and Building Materials Department, National Research Centre, Cairo, Egypt; 3Desamanera Srl, Rovigo, Italy; 4Centro de Tecnología de Recursos Minerales y Cerámica (CETMIC), Gonnet (La Plata), Argentina; 5Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA, USA

Additive manufacturing of construction materials is an innovative, challenging research field, with the potential of producing parts with complex structures, and specific functional or structural properties. In the current research, a binder jetting printer was employed to fabricate geopolymer-based components. The printing bed was comprised of lightweight aggregates, reactive metakaolin, and waste materials, which were activated by the selective deposition of an alkaline solution (silicate-based solution). The reaction parameters were controlled to achieve an adequate setting time enabling rapid printing with the suitable resolution, and the building up of a structure at the macro-scale (meter-size). The main chemical, physical and mechanical characteristics of the printed parts were investigated.
This work was carried out in the framework of the IDEAL project (KAVA Reference Number: 19040).


CN-2:L04  Geopolymer Materials developed in a Configuration Suitable for Photovoltaic Application
A. BAFTI, F. Brleković, V. Mandić, I. Panžić, Faculty of Chemical Engineering and Technology, Zagreb, Croatia; L. Pavić, Ruđer Bošković Institute, Zagreb, Croatia; G. Mali, National Institute of Chemistry, Ljubljana, Slovenia

Geopolymers are nowadays considered as the third generation of concrete due to their sustainability in the preparation of cement. Specifically, a much lower environmental footprint is present which significantly reduces CO2 emission and helps in terms of resolving environmental issues worldwide. Certain contributions in the overlapping area of construction and energy materials could arise from preparing geopolymers in the form of a paste, which is then further developed into thin-films. In this work, we focused on chemical and (micro)structural changes that occur during the curing of (pre)mullite-based geopolymers. The influence of various factors was tested, such as the presence of ions in the activation solution and presence of additives for acgieveing desired properties of the composite. Therefore, we prepared samples in bulk and thin-film configuration which were characterized by DTA-TGA, XRD, SEM, MAS NMR and SS-IS. Particular attention was devoted to improving conductivity by adding various conductive polymers to the geopolymer matrix. Obtained results enabled a better understanding of the patway towards desired properties. We present a challenging shift from relatively porous bulk to thin-films, broadening the applicability of geopolymers to vertically mounted solar-cells.


CN-2:L05  Alkali Activation of Ceramic Waste for Thermal Insulation Application
G. Masi, M.C. Bignozzi, Department of Civil, Chemical, Environmental and Materials Engineering, University of Bologna, Bologna, Italy

One of the potentialities of alkali activated materials is the possibility to use locally available aluminosilcate precursors to produce hardened materials for several applications. However, this aspect implies the optimization of the mix design to tailor the properties of the final product. This study was aimed at optimizing the alkali activation of ceramic waste sourced from porcelain tiles grinding, being the most produced ceramic tiles in Italy. Optimization of the mix design was carried out tailoring fundamental molar ratios and relevant curing temperature. Promising results were achieved activating the investigated ceramic waste by sodium hydroxide and sodium silicate solutions when curing was at 50°C for 24 h. With the optimized mix design, light-weight materials were prepared with the final goal of thermal insulation application. Different direct foaming methods (sodium dodecyl sulphate (SDS), hydrogen peroxide, sodium bicarbonate and recycled metallic aluminium) were investigated and their amount was optimized in terms of geometric density and total open porosity. It was found that the lightest materials were obtained by the combination of SDS and hydrogen peroxide (both at 1 wt%) and the addition of expanded perlite (ranging from 5 to 10 wt%) as light-weight aggregate.


CN-2:IL06  Chemical and Environmental Assessment of Alkali Activated Materials based on Different Precursors
I. LANCELLOTTI, University of Modena and Reggio Emilia, Dept. of Engineering Enzo Ferrari, Modena, Italy

Many non conventional aluminosilicates precursors can be exploited in the formulation of alkali activated materials (AAMs). -Etna volcano produces high amorphous volcanic ash and paleo-soils (ghiara) with low reactivity requiring thermal treatments for activation. Many formulations were prepared to avoid it in order to make them usable in restoration sites. The mechanical strength is strongly dependent on the metakaolin amount (10-38 MPa), porosity 25%; water absorption 9-15%, eluates conductivity 20-350 mS/m confirm the occurring of alkali activation and potential for these pyroclastic wastes for valorization in the restoration field. - Pumice and lapillus (quarry scraps of national volcanic minerals) were employed in the tailoring and characterization of geopolymers by substituting metakaolin (70 - 80 wt%). The lapillus-containing sample results more consolidated (compressive strength in the range 35-38 MPa against 6-8 MPa of pumice ones). - Electric arc furnace stainless steel slag and secondary metallurgical slag (ladle slag) AAMs show that all bivalent ions are immobilized in a geopolymeric matrix. While, amphoteric elements, such as As and Cr, show higher mobility than the corresponding slag in both the environments.


CN-2:L08  Chemical and Antibacterial Properties of Al2O3-corundum Powders in MK-geopolymer Matrix
G. DAL POGGETTO1, L. Barbieri1, M. Catauro2, C. Leonelli1, 1Department of Engineering “Enzo Ferrari”, University of Modena and Reggio Emilia, Modena, Italy; 2Department of Industrial Engineering, University of Campania “Luigi Vanvitelli”, Aversa, Italy

In this work, the chemical, physical and antibacterial properties of geopolymers based on metakaolin and waste corundum at different percentages is presented. The samples were prepared by alkaline activation of a mixture of metakaolin and corundum powder from abrasion tests with the addition of NaOH and sodium silicate solution. Crystalline phases of the geopolymers and raw materials (MK and WC) were identified by X-ray diffraction (XRD). Fourier transform infrared spectroscopy analyzes were carried out in order to highlight the reactivity of the waste corundum in terms of Si - O and Si - O - Al bonds. Ionic conductivity and pH of the eluate after 7, 14 and 28 days of curing at room temperature were carried out. Finally, antibacterial tests for ecological and antibacterial evaluation were carried out on the consolidated materials testing the microbial growth of Escherichia coli and Enterococcus faecalis after 24 and 48 hours, respectively.


CN-3:IL02  Geopolymer Beads and Applications
E. Papa, E. Landi, V. Medri, CNR-ISTEC, Faenza, Italy

Geopolymer-based beads were produced exploiting spherification processes in order to obtain millimeter-size porous beads useful for adsorption purposes. Adsorbents in form of beads offer some advantages as a good mobility, high packing density, ease of separation and reuse after regeneration. Furthermore, adsorption is considered one of the easiest and most effective techniques and alternative and low cost adsorbents, obtained by simple processes, are always researched. For these reasons, starting from different mixtures, obtained from metakaolin and potassium silicate solutions, geopolymer-based beads were formed through an injection-solidification method in different media: polyethylene glycol, liquid nitrogen and calcium chloride (using the ionotropic gelation of the alginate added to the mixture). The optimization of the processes allowed to obtain reproducible, round and mechanically resistant beads. The beads were characterized in term of morphology, macro- and microstructure, composition-stoichiometry, porosity distribution and specific surface area. Adsorption tests were carried out using dyes with different concentration and attempts to promote adsorption were made formulating composite beads containing hydrotalcite or TiO2 (exploiting its photodegradation effect).


CN-3:L04  Influence of Metakaolins Reactivity on the Properties of Geopolymers
W. N'CHO, J. Jouin, S. Rossignol, IRCER, Institute for Research on Ceramics (UMR CNRS 7315), European Center for Ceramics, Limoges Cedex, France

The search for new, more economical, energy-efficient and less polluting binders, such as geopolymer materials, has been favored by the imperatives of preserving the environment and in the context of sustainable development. These binders result from the activation of aluminosilicate sources of different origin (metakaolin, fly ash…) by either an alkaline or acidic solution. Due to their wide field of applications, the properties of these materials and reagents are largely studied. However, to date, these studies are still very dependent on the initial reagents, and the fundamental link between the global characteristics of the aluminosilicate source, their reactivity and the final properties of the geopolymers, has not yet been defined. To answer this problem, the proposed work consists in studying a selection of several metakaolins, pure or mixed, to characterize their reactivity and to understand how they will influence the properties of the samples. First, mixtures of French metakaolins of different chemical composition and purities were carried out in order to assess their reactivity towards the activating solution, using physicochemical (wettability, zeta potential) and structural (X-ray diffraction, Fourier transform infrared spectroscopy…) techniques. The results show that whatever the techniques used, the behavior of metakaolins mixtures strongly depend on the molar ratio of aluminum in the composition. Also, geopolymers have been formulated from these mixtures and submitted to mechanical tests including compressive strength in order to compare the variations in composition, reactivity and mechanical properties.


CN-3:IL06  Geopolymer-based Heterogeneous Catalysts: Potential and Future Prospects
M.I.M. Al-Zeer, M. Illikainen, Fibre and Particle Engineering Research Unit, University of Oulu, Oulu, Finland

The search for a solid catalyst that has the acidity and chemical stability of zeolites combined with structural flexibility of amorphous silica alumina (ASA) remains a challenge. The potential of geopolymers as solid catalysts has recently attracted much attention in a range of organic synthesis and important ecological applications. This talk underscores the versatility of geopolymers as heterogeneous catalysts for a variety of chemical processes, both as intrinsic catalysts made possible by exploiting their ion exchange properties to form Brønsted and Lewis acid sites, and as scaffolds for a wide range of other catalytic reactive species. In addition, future directions towards tailoring geopolymers textural and structural properties in order to maximise their catalytic efficiency will be presented.


CN-3:L07  Asymmetric Metakaolin-based Geopolymer Membranes: Synthesis and Characterization
A. FILIPPONI, G. Masi, S. Bandini, M.C. Bignozzi, University of Bologna, Department of Civil, Chemical, Environmental and Materials Engineering, Bologna, Italy

The aim of this study was to develop an asymmetric metakaolin-based geopolymer membrane cured at temperatures lower than 70°C, with properties similar to ceramic membranes. The support has been obtained by pressing a dry powder, using metakaolin and anhydrous sodium metasilicate as raw materials. Optimized parameters (Na/Al = 0.9, H2O = 12 wt% and forming pressure of 5 MPa) have been identified in order to obtain a material with a total open porosity of 30 % and a pore size of 15 µm, compatible with microfiltration. Geopolymeric selective layer has been successfully deposited on top of the support by spatula coating technique, obtaining a thickness of 40 µm and a pore size distribution between 0.1 and 1 µm. The asymmetric membrane has been tested for permeability to pure water and solutions with transmembrane pressures below 1.2 bar. The rejection characterization was conducted by measuring the separation efficiency of suspended particles and oil/water emulsions for industrial wastewater treatment and hydrocarbon production. This microfiltration system appears to be a cheaper alternative option for existing microfiltration ceramic membrane.


CN-3:IL08  Corrosion of Reinforcing Steel in Alkali Activated Building Materials
M. SERDAR, A. RUNCI, Department of Materials, Faculty of Civil Engineering, University of Zagreb, Croatia

Conventional cement-based concrete is a good pair for reinforcing steel. Cement-based concrete carbonates relatively slowly in a low carbon dioxide atmosphere; well-designed concrete allows only slow diffusion of chlorides and can even physically and chemically bind chlorides. Once the physical and chemical properties of the binder in concrete are changed, a myriad of problems can arise. With alkali-activated materials (AAM) the situation is even more complex as the term alkali-activated materials covers a wide range of precursors and activators, making generalisation virtually impossible. This paper discusses some of the challenges in researching corrosion of reinforcing steel in AAMs. First, some of the methods or coefficients that have been used for decades for conventional concrete need to be adapted for AAMs. Second, the way chlorides and carbon dioxide penetrate through and bind to AAMs can differ significantly from conventional concrete, due to differences in pore structure, tortuosity, and chemistry of reaction products. Finally, the bond and interface between steel and AAM can also be different. Consequently, these differences could lead to changes during the propagation phase of corrosion, and affect the time to cracking and the service life of the structures.


CN-3:IL09  Porous Waste-based Inorganic Polymers for Innovative Applications
R.M. Novais, J. Carvalheiras, J.A. Labrincha, Department of Materials and Ceramic Engineering / CICECO-Aveiro Institute of Materials, University of Aveiro, Campus Universitário de Santiago, Aveiro, Portugal

Despite decades of intensive research, inorganic polymers have yet to reach their full potential. There are several reasons hindering their wider use. One of the major barriers is the fact they have been mainly considered as an alternative to Portland cement, which has been the benchmark material in construction over the last century. Using inorganic polymers in other less investigated, but high added-value, applications (e.g. wastewater treatment and renewable energy systems) might be a key driver to foster the use of this technology. In addition to their remarkable properties, inorganic polymers can incorporate into their composition various wastes or industrial by-products, which might contribute towards the circular economy. In this lecture, the feasibility of using porous inorganic polymers and alkali-activated materials as waste-based bulk-type adsorbents for dyes and heavy metals removal from wastewaters, as anaerobic digestion enhancers, and as thermal and acoustic insulators will be demonstrated.


CN-4:IL01  Technical Assessment and Regulation for Alkali Activated Building Products
V. Ducman, K. Traven, M. PAVLIN, B, HORVAT, ZAG, Ljubljana, Slovenia

Alkali activation technology (AAT) is an emerging technology in the construction sector. Its progress into regular production is slower than expected, due to the two main reasons: i) AAT is a complex process especially if based on the waste materials where diversity and constancy of the precursor/activator’s properties might present a problem in providing durable products with long term constant properties, and ii) legislation; because before such products are positioned on the market, and especially if they are intended to be used in building sector, specific regulation is applicable in Europe which is set in Construction Product Regulations (CPR, No 305/2011). CPR foresees either harmonised European norm (hEN) or European Technical Assessment (ETA) to be followed in technical evaluation of such products. Selected case studies of AAM products from upscaling projects will be presented with a focus on their performance characteristics and potential drawbacks. Namely, it is important that final use and targeted properties are defined as early as possible, and also that test protocols are properly selected. Finally, the procedure on how to obtain proper technical documentation for different AAM products will be proposed.


CN-4:IL02  New Cements for the 21st Century: The Pursuit of an Alternative to Portland Cement
A. Fernández-Jiménez, I. Garcia-Lodeiro, A. Palomo, Eduardo Torroja Institute (Ietcc-CSIC), Madrid, Spain

The OPC production contributes 2-3% of global energy use and 5% to 7% of world-wide carbon dioxide emissions (CO2). According to estimates in 2050, the CO2 emissions associated with the manufacture of OPC could increase between 240-260% compared to the 1990 emissions. Faced with this need, the Portland cement industry has been considering several options. An innovative option is to produce cements with very low OPC clinker contents, or without clinker applying the knowledge of alkaline cement technology. Alkaline activation is a versatile process that can allow the use of a great variety of materials in the system SiO2-Al2O3-CaO in order to make a product with good cementitious properties. Different groups can be distinguish: i) Group 1. Activation of calcium- and silicon-high materials as blast furnace slag. The main reaction product is a C A S H gel (2D structure). ii) Group 2. Activation of aluminium and silicon rich materials with low CaO contents, (i.e. metakaolin (MK) or fly ash (FA). The main product here is a N-A-S-H gel with 3D structure. iii) Group 3. Activation of materials with moderate calcium, silica and aluminium content, a mixture of precursors (slag/FA, slag/FA/MF and the so-called “alkali hybrid cement” (low OPC+ fly ash, MK, etc.), and low alkaline activator.


CN-4:L03  Variability of Mix Design used for Pilot Production of Façade Panels: the Influence on Mechanical Properties, Microstructure and Leaching Behavior
M. PAVLIN, B. Horvat, V. Ducman, Slovenian National Building and Civil Engineering Institute, Ljubljana, Slovenia; B. Matko, A. Pavlin, Termit d.d., Moravče, Slovenia

About 2.5 Mt of mineral wool waste is produced in the European Union every year. Because of its low density, it poses a problem ranging from transportation to the use of space in landfills. Alkali-activation of this silicon-rich waste represents an alternative to disposal. In the Wool2loop project, we produced various construction products based on waste mineral wool, e.g. insulation boards, façade panels, pavements etc. Our task was to develop and optimise a mix design for façade panels consisting of 70 w.t. % of stone wool, while the remaining solid materials are electric arc furnace slag, metakaolin, lime and quartz sand. The mixture could vary during pilot production due to differences in the amount of ingredients as well as the particle size of the waste mineral wool as the main precursor. These variations were observed from the results of mechanical strength, slump test, the curvature of the panels and freeze-thaw test behaviour. Leaching tests were also performed to evaluate the effect of changing parameters on the immobilisation/leaching of toxic elements.


CN-4:L04  Olive Pomace Ash as an Alternative Alkaline Activator of Electric Arc Steel Slags in the Manufacture of Alkaline Activated Cements
D. Eliche-Quesada, F. ANDRES-CASTRO, M.A. Gómez-Casero, L. Pérez-Villarejo, J.S. Bueno-Rodríguez, Department of Chemical, Environmental, and Materials Engineering, Higher Polytechnic School of Jaén, University of Jaen, Jaén, Spain

In this work, the feasibility of the development of alkaline activated cements has been studied, using as an alternative alkaline activator, pomace fly ash (PFA) for the activation of electric arc steel slags (BFS). The physical, mechanical and thermal properties of the cements in which BFS was replaced by PFA have been studied and compared with the cements obtained using a KOH commercial solution in the range of 4-8 M. The results obtained have shown that the properties of slag cements alkaline activated using pomace ashes are superior to those obtained when the slags are activated by commercial activating solutions, KOH solutions. Therefore, the feasibility of using pomace fly ash as a potential alkaline activator in the manufacture of alkaline activated materials has been demonstrated, presenting the new sustainable materials obtained, with important economic and environmental advantages.
Acknowledgements This work has been funded by the project Development and characterization of new geopolymerical composites based on waste from the olive industry. Towards a sustainable construction MAT2017-88097-R, funded by MCIN/ AEI /10.13039/501100011033/ FEDER “A way of making Europe” and project Applying the Circular economy in the development of new low carbon footprint alkaline activated hydraulic binders for construction solutions PID2020-115161RB-I00 funding by MCIN/ AEI /10.13039/501100011033


CN-4:IL06  Tools of NMR to Understand Geopolymers
I. Sobrados DE LA PLAZA, Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain

Solid-state NMR is a suitable and increasingly used technique for the study of the structural properties of a wide variety of amorphous or low crystalline materials. In the case of geopolymers, the analysis of the spectra of different systems allows studying the evolution of the crystalline and amorphous phases of the raw materials and also the hydration and alkaline activation reactions in order to establish the effect of alkali and soluble aluminum and silica in the nature and nanostructure of the gels obtained. The NMR-MAS applied to cementitious materials allows a better understanding of the reaction mechanisms of the alkaline activation of aluminosilicate materials, the study of the local structure of the gels formed in the different stages (closely related to mechanical performance and chemical properties of the binder) and the final workability. This will be covered by first presenting some well known examples of MAS monodimensional experiments of the most frequent nuclei in cementitious materials such as 1H, 27Al, 29Si and 23Na. To continue some examples of advanced multidimensional techniques will be exposed and finally, future methodological prospects with the application of high magnetic fields in the characterization of isotopes of very low sensitivity and abundance.


CN-4:IL07  Laterites (natural iron-rich aluminosilicates) as Sustainable Raw Solid Precursor for Geopolymers
E. KAMSEU1, 2, R. Kaze1, C. Leonelli2, 1Local Materials Promotion Authory/MIPROMALO, Yaoundé, Cameroon; 2Department of Engineering “Enzo Ferrari”, University of Modena and Reggio Emilia, Modena, Italy

Laterites are a particular class of natural aluminosilicates abundantly available in the tropical and subtropical regions of the World. It formation at the surface and the natural corrosion of the kaolinite by iron minerals make the raw material appropriate for their use as solid precursor for geopolymerization without any precalcination. In alkaline solution, the metastable kaolinite (principal mineral) is dissolved together with goethite, hematite and others iron derived oxi and oxihydroxides to form various classes of oligomers. The oligomers are polymerized/polycondensed to polysialates, ferrosialates and ferrisilicates. Room temperature curing conducts to geopolymer with mechanical strength (5-7 MPa in flexion; 20-25 MPa in compression) close to that of standard metakaolin based geopolymers while steam curing increases significantly the volume of ferrisilicates responsible for the development of high strength binders particularly when the chemical stoichiometry of the gel is optimized: Flexural strength of > 20 MPa is then achieved. Micromechanical characterizations, ESEM, Spectroscopy Mossbauer and FT-IR allowed to understand the phases evolution and strengthening mechanisms of laterites based geopolymer cement and composites.

 

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