and to the synthesis of foamed geopolymers
Ercoli R.*1, Renzulli A.1, Orlando A.2, Tassi F.3, Pagnetti A.4, Vaselli O.3, Borrini D.3, Paris E.5, Tarantino S.C.6 & Di Gregorio A.7
1 Dipartimento di Scienze Pure e Applicate, Università di Urbino.
2 IGG – CNR Firenze.
3 Dipartimento di Scienze della Terra, Università di Firenze.
4 Laboratorio ARCA Srl, Fano.
5 Scuola di Scienze e Tecnologie, Università di Camerino.
6 Dipartimento di Scienze della Terra e dell’Ambiente, Università di Pavia.
7 CRIET, Università di Milano Bicocca.
Corresponding email: [email protected] Keywords: Aluminium, Hydrogen, geopolymers.
Valorization of the so-called “industrial by-products” is of a paramount importance for (i) the sustainability of raw material exploitation and management, (ii) limiting the greenhouse gases emissions and (iii) reducing the amount of waste to landfill. A fundamental principle of circular economy and sustainable development focus on the use of residual products from industrial processes or from end-of-life materials, with the goal to valorize them for new application and minimizing the waste production. For this purpose, the University of Urbino is working on an innovative PhD project, financially supported by the Regione Marche (Fondazione Cluster Marche). Its aim is the disposal and re-use of industrial waste from two local industries: Profilglass SpA dealing with specific treatments of aluminium profiles, pipes and laminates for different sectors such as construction, automotive, electronics, mechanics and many others, and Faber vetreria Srl which is a glassware industry supplier of the most important European companies. Experimental tests firstly involved industrial by-products of Profilglass SpA, produced from three main processes of the aluminium recycling: (a) sifting, (b) pyrolysis and (c) melting. To inertize the above mentioned highly water-reactive materials, that release significative amounts of H2 from metals, the reaction series were tested and monitored in laboratory. Obviously, aluminium is the most abundant metal species and therefore the main source for the release of hydrogen, given by:
(1) 2Al + 6H2O + 2NaOH → 2NaAl(OH)4 +3 H2 (2) NaAl(OH)4 → NaOH + Al(OH)3
(3) Al(OH)3 + Al(OH)3 → Al2O3+3H2O
The experiments were performed by mixing industrial waste to an aqueous alkaline solution in a stainless-steel compact reactor (series 5500 HP T316, 25 ml, Parr Instrument Company) equipped with gas inlet and outlet valves, liquid sampling valve and internal thermocouple in addition to the internal magnetic stirrer. In order to synthesize geopolymers through alkaline activation, the aluminium industrial by-products will be mixed to silica-rich waste of the glass industry, which requires the disposal of sludges from the filtration of glass processing, performed by a high-pressure water jet. The production of H2 will allow to produce foamed geopolymers with pockets of hydrogen trapped in pores throughout the body of a high strength and hardness material, which is suitable not only as insulation material but also for electronic applications. An essential physical characteristic of geopolymers is also the resistance to mechanical, thermal and atmospheric degradation, parameters suitable to trap polluting and toxic substances.
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FT-IR study of early stages of geopolymer gel formation of AAMs based on pyroclastic deposits (Mt. Etna, Sicily, Italy) using two different alkaline solutions
Finocchiaro C.*1, Barone G.1, Mazzoleni P.1, Leonelli C.2 & Rossignol S.3
1 Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Università di Catania.
2 Dipartimento di Ingegneria “Enzo Ferrari”, Università di Modena e Reggio Emilia.
3 IRCER (Institut de Recherche sur les Céramiques) University of Limoges.
Corresponding email: [email protected]
Keywords: innovative materials, alkaline activation, restoration.
The huge quantity of volcanic ash and paleo-soils deposits, locally named “ghiara”, of Mt. Etna volcano encouraged us to test them for alkali activated materials (AAM) production. Ghiara paleo-soils is characterized by an intense reddish hue due to oxidation transformations occurred during Etna’s lava flow. It was widely used in XVII-XVIII centuries, as aggregate for mortar and plaster production due to its high hydraulic modulus (Battiato, 1998; Belfiore et al., 2010). However, the use of traditional recipes based on OPC and lime binders caused degradation forms and durability problems in historical Baroque buildings of the city (belonging to UNESCO heritage list).
This research, supported by the AGM for CuHe project (PNR fund), aims to use these volcanic raw materials as aluminosilicate precursors for AAMs production to be applied in Cultural Heritage of Catania architecture.
In this way, ghiara paleo-soils can be used in an innovative way, able to overcome durability problems of old mortars and, on the other hand, volcanic ash can become an important resource, so to solve the emergency during explosive eruptions.
In this work, FT-IR analysis with KBr method were carried out on raw materials both room temperature and after thermal treatments (200°C, 300°C and 400°C) to determine their reactivity in order to understand the polycondensation reaction in presence of alkaline solutions. Several formulations were prepared based on sodium or potassium silicate solutions with the addition of metakaolin. The reactive mixture was analysed by in situ following FT-IR measurements to evidence the aluminosilicate network reticulation (Gharzouni et al., 2015). Compressive test at 7 and 21 days were performed on each family to determine the mechanical strength, obtaining good results, especially for those ones with 20% of metakaolin and potassium alkaline solution.
Finally, the proposed methodological approach was useful to determine and validate the feasibility of formulations considered and to compare the reaction behaviour, and so the polycondensation rates of the two different alkali solutions used.
Battiato G. (1988) - Le Malte Del Centro Storico Di Catania. Documenti Dell’Istituto Dipartimentale Di Architettura e Urbanistica Dell’Università Di Catania, 16, 85–107.
Belfiore M.C., La Russa F.M., Mazzoleni P., Pezzino A. & Viccaro M. (2010) - Technological study of ‘‘ghiara’’ mortars from the historical city centre of Catania (Eastern Sicily, Italy) and petro-chemical characterisation of raw materials.
Environ Earth Sci., 61, 995-1003.
Gharzouni A., Joussein E., Samet B., Baklouti S. & Rossignol S. (2015) - Effect of the reactivity of alkaline solution and metakaolin on geopolymer formation. Journal of Non-Crystalline Solids, 410, 127-134.
Red brick waste as geopolymeric precursor for a sustainable restoration of ancient masonry
Fugazzotto M.*1-2, Coccato A.1, Finocchiaro C.1, Occhipinti R.1, Stroscio A.1, Mazzoleni P.1 & Barone G.11 Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Università di Catania.
2 Dipartimento di Scienze Umanistiche, Università di Catania.
Corresponding email: [email protected] Keywords: geopolymers, brick waste, sustainable restoration.
The conservation of archaeological sites, exposed to the current adverse environmental conditions, is nowadays a challenge for the Cultural Heritage policy. The research on new solutions for the ceramic restoration is also encouraged by the limits of compatibility, effectiveness and durability of the traditional lime or organic resin and by their energy-consuming.
In the optic of a sustanable conservation practices a novel class of materials named Alkaline Activated Materials (AAMs) emerges. AAMs, including those called geopolymers, have chemical and mineralogical similitude to the ceramic materials and their tailored designed structural and chemical characteristics make them a good candidate for ceramic restoration (Reig et al., 2013; Ricciotti et al., 2017).
This research, supported by the AGM for CuHe project (PNR fund), aims to investigate the feasibility of reusing red clay brick waste as precursors in the alkali activation process, in order to produce innovative restoration materials for brick masonries.
Bricks were grinded lower than 10 micron size and activated with NaOH and Na2SiO3 solution in different proportions. Liquid/solid ratio has been varied in order to modify the workability of the final products.
Geopolymer pastes have been cured either at room temperature or in oven at 65°C for 24 hours. After curing time samples were stored in a chamber with RH 99% for 7 and 28 days.
Formulation and chemical parameters have been varied, involving in some case the addition of metakaolin, in order to develop three types of final products: a mortar for repointings, a paste for new blocks useful in replacements and a blend for consolidations.
To evaluate the effectiveness of the red brick-based geopolymers for restoration purpose, the products were tested on archaeological remains and their performance was evaluated. Morphological and chemical analysis has been carried out by means of SEM-EDS, in order to observe the adhesion at the interface between the substrate and the geopolymer. In order to assess their compatibility and efficacy, mechanical tests and porosity analysis were performed on geopolymer samples. The results reveal that geopolymer pastes made with recycled brick waste are an interesting alternative to the most commonly used materials in the field of brick masonry restoration, both in structural and not structural interventions. Moreover it is worthy to note that the possibility to use raw materials with similar chromatic appearance with the substrate to restore allows to reach a very good aesthetic compatibility, essencial requisite in the restoration field.
Reig L., Tashima M.M., Borrachero M.V, Monzò J., Cheeseman C.R. & Paya J. (2013) - Properties and microstructure of alkali-activated red clay brick waste. Constr Build Mater., 43, 98-106.
Ricciotti L., Molino A.J., Roviello V., Chianese E., Cennamo P. & Roviello G. (2017) - Geopolymer composites for potenzial applications in Cultural Heritage. Environments, 4, 91.
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