Development of Inorganic Polymers and Geopolymers

A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Polymer Composites and Nanocomposites".

Deadline for manuscript submissions: closed (30 April 2023) | Viewed by 17114

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Guest Editor
Department of Engineering “Enzo Ferrari”, University of Modena and Reggio Emilia, 41125 Modena, Italy
Interests: materials science; inorganic solids; chemistry; silicates; glasses; microwave processing
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Special Issue Information

Dear Colleagues,

As Guest Editors of the Special Issue "Development of Alkali Activated Inorganic Polymers and Geopolymers " we cordially invite you to contribute with research articles, review articles, short communications, technical notes or perspectives. This Special Issue will be a collection of articles from top researchers describing new developments or new cutting-edge applications in the fields of Polymers, Polymer Chemistry, and Composite Materials, Building Materials, Sustainable Materials, as well as in other related scientific fields.

This Special Issue aims to integrate experimental data and models from different disciplines, such as materials chemistry, materials engineering, inorganic chemistry, mineralogy, waste management, sustainability, green economy, etc. to better understand the processes and mechanisms governing the evolution and performances of alkali activated materials from synthesis to application. Works that integrate different disciplines are particularly welcome.

Prof. Dr. Cristina Leonelli
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Polymers is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • geopolymers
  • alkaline activation
  • mineralogy
  • microstructure (FT-IR, RAMAN, XRD, SAXS SEM, TEM, XRF, XANES, XPS, etc.)
  • metakaolin
  • mechanical properties
  • waste reused and upcycle
  • fly ash
  • eco-friendly materials
  • sustainable materials
  • thermal behavior
  • antibacterial properties
  • green economy

Published Papers (7 papers)

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Research

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17 pages, 4689 KiB  
Article
Mosses on Geopolymers: Preliminary Durability Study and Chemical Characterization of Metakaolin-Based Geopolymers Filled with Wood Ash
by Michelina Catauro, Veronica Viola and Alberto D’Amore
Polymers 2023, 15(7), 1639; https://doi.org/10.3390/polym15071639 - 25 Mar 2023
Cited by 3 | Viewed by 1401
Abstract
Burning wood is estimated to produce about 6–10% of ash. Despite the possibility of recycling wood ash (WA), approximately 70% of the wood ash generated is landfilled, causing costs as well as environmental pollution. This study aims to recycle WA in an alternative [...] Read more.
Burning wood is estimated to produce about 6–10% of ash. Despite the possibility of recycling wood ash (WA), approximately 70% of the wood ash generated is landfilled, causing costs as well as environmental pollution. This study aims to recycle WA in an alternative way by inserting it as filler in geopolymeric materials. Here, metakaolin, NaOH, sodium silicate, and WA are used to realize geopolymers. Geopolymers without and with 10, 20 and 30% of WA are synthesized and characterized after 7, 14, 28 and 56 days. The article’s study methods are related to geopolymers’ chemical, biological and mechanical properties. The geopolymers synthesized are compact and solid. The pH and conductivity tests and the integrity and weight loss tests have demonstrated the stability of materials. The FT-IR study and boiling water test have confirmed the successful geopolymerization in all samples. The antibacterial analysis, the moss growing test and the compressive strength test have given a first idea about the durability of the materials synthesized. Furthermore, the compressive strength test result has allowed the comparison from the literature of the specimens obtained with the Portland cement (PC). The results obtained bode well for the future of this material. Full article
(This article belongs to the Special Issue Development of Inorganic Polymers and Geopolymers)
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29 pages, 11405 KiB  
Article
Investigation of the Mechanical Properties of Quick-Strength Geopolymer Material Considering Preheated-to-Room Temperature Ratio of Sand, Na2SiO3-to-NaOH Ratio, and Fly Ash-to-GGBS Ratio
by Mohammad Rizwan Bhina, Kuang-Yen Liu, John-Eric Hsin-Yu Hu and Chih-Ta Tsai
Polymers 2023, 15(5), 1084; https://doi.org/10.3390/polym15051084 - 21 Feb 2023
Cited by 4 | Viewed by 1842
Abstract
Geopolymer concrete is a useful alternative construction material for bridge deck systems, as it is characterized by a low carbon footprint, rapid setting, quick strength development, low cost, freeze-thaw resistance, low shrinkage, and sulphate and corrosion resistance. Heat curing enhances the mechanical properties [...] Read more.
Geopolymer concrete is a useful alternative construction material for bridge deck systems, as it is characterized by a low carbon footprint, rapid setting, quick strength development, low cost, freeze-thaw resistance, low shrinkage, and sulphate and corrosion resistance. Heat curing enhances the mechanical properties of geopolymer materials (GPM), but it is not suitable for large structures, as it affects construction activities and increases energy consumption. Therefore, this study investigated the effect of preheated sand at varying temperatures on GPM compressive strength (Cs), the influence of Na2SiO3 (sodium silicate)-to-NaOH (sodium hydroxide—10 molar concentration), and fly ash-to-granulated blast furnace slag (GGBS) ratios on the workability, setting time, and mechanical strength properties of high-performance GPM. The results indicate that a mix design with preheated sand improved the Cs of the GPM compared to sand at room temperature (25 ± 2 °C). This was caused by the heat energy increasing the kinetics of the polymerization reaction under similar curing conditions and with a similar curing period and fly ash-to-GGBS quantity. Additionally, 110 °C was shown to be the optimal preheated sand temperature in terms of enhancing the Cs of the GPM. A Cs of 52.56 MPa was achieved after three hours of hot oven curing at a constant temperature of 50 °C. GGBS in the geopolymer paste increased the mechanical and microstructure properties of the GPM as a result of different formations of crystalline calcium silicate (C-S-H) gel. The synthesis of C-S-H and amorphous gel in the Na2SiO3 (SS) and NaOH (SH) solution increased the Cs of the GPM. We conclude that a Na2SiO3-to-NaOH ratio (SS-to-SH) of 5% was optimal in terms of enhancing the Cs of the GPM for sand preheated at 110 °C. Additionally, as the quantity of ground GGBS in the geopolymer paste increased, the thermal resistance of the GPM was significantly reduced. Full article
(This article belongs to the Special Issue Development of Inorganic Polymers and Geopolymers)
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17 pages, 4103 KiB  
Article
Alkali-Activated Binary Binders with Carbonate-Rich Illitic Clay
by Angela D’Elia, Marina Clausi, Ana Fernández-Jiménez, Angel Palomo, Giacomo Eramo, Rocco Laviano and Daniela Pinto
Polymers 2023, 15(2), 362; https://doi.org/10.3390/polym15020362 - 10 Jan 2023
Cited by 5 | Viewed by 1707
Abstract
This work deals with the investigation of alkaline binders obtained from binary mixtures of carbonate-rich illitic clay from deposits in southern Italy and two industrial by-products with very different total composition and calcium content, i.e., blast furnace slag and type F fly ash, [...] Read more.
This work deals with the investigation of alkaline binders obtained from binary mixtures of carbonate-rich illitic clay from deposits in southern Italy and two industrial by-products with very different total composition and calcium content, i.e., blast furnace slag and type F fly ash, respectively. To improve the reactivity, the selected clay was ground in a ball miller and heated to 700 °C. The binary mixtures were alkali activated with NaOH solution at 4 M and 8 M, and the activated pastes were cured at room temperature and relative humidity >90% in a climatic chamber. Heat flow, total heat and compressive strength (2, 7 and 28 days) were determined. The hardened pastes were characterized by X-ray powder diffraction (XRPD), Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX). Results show that the main reaction product in all samples is a gel or mixture of C-A-S-H/(N, C)-A-S-H type gel depending on the calcium content in the precursors. The paste, made up of a 1:1 weight proportion of carbonate-rich illitic clay and blast furnace slag, showed the formation of a more compact matrix than that observed in each individually activated component, achieving the considerable mechanical strength value of 45 MPa after 28 days, which suggests a very positive interaction between the two calcium-rich solid precursors. The binary mixture of carbonate-rich illitic clay and F fly ash showed relatively low compressive strength (below 15 MPa), which has been related to the poor reaction potential of fly ash regarding the alkali activation at room temperature. The modification of curing parameters is expected to improve the reaction of carbonate-rich illitic clay/fly ash blend. The clay activation method used in this study has been demonstrated to be suitable for larger scale industrial pre-treatment set-ups. Full article
(This article belongs to the Special Issue Development of Inorganic Polymers and Geopolymers)
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17 pages, 4586 KiB  
Article
Sustainable Materials Based on Geopolymer–Polyvinyl Acetate Composites for Art and Design Applications
by Laura Ricciotti, Alessio Occhicone, Stefania Manzi, Andrea Saccani, Claudio Ferone, Oreste Tarallo and Giuseppina Roviello
Polymers 2022, 14(24), 5461; https://doi.org/10.3390/polym14245461 - 13 Dec 2022
Cited by 6 | Viewed by 1844
Abstract
The recent introduction of the Next Generation EU packages on the circular economy and the Italian Ecological Transition Plan has further boosted the research of effective routes to design materials with low energy and low environmental impact, in all areas of research, including [...] Read more.
The recent introduction of the Next Generation EU packages on the circular economy and the Italian Ecological Transition Plan has further boosted the research of effective routes to design materials with low energy and low environmental impact, in all areas of research, including art and design and cultural heritage. In this work, we describe for the first time the preparation and characterization of a new sustainable adhesive material to be used in the art and design sector, consisting of a geopolymer-based composite with polyvinyl acetate (PVAc), both considered more environmentally acceptable than the analogous inorganic or polymeric materials currently used in this sector. The key idea has been the development of organic–inorganic composites by reacting low molecular weight polymers with the geopolymer precursor to obtain a material with reduced brittleness and enhanced adhesion with common substrates. Structural, morphological, and mechanical studies pointed out the consistent microstructure of the composite materials if compared to the neat geopolymer, showing lower density (up to 15%), improved flexural strength (up to 30%), similar water absorption and a relevant toughening effect (up to 40%). Moreover, the easy pourability in complex shapes and the excellent adhesion of these materials to common substrates suggest their use as materials for restoration, rehabilitation of monuments, and decorative and architectural intervention. The organic–inorganic nature of these new materials also makes them easily recognizable from the support on which they are used, favoring, in line with the dictates of good restoration practices, their possible complete removal. For all these reasons, these new materials could represent promising candidates to overcome the limits related to the creative industry for what concerns the selection of environmentally friendly materials to meet design requirements with low environmental impacts. Full article
(This article belongs to the Special Issue Development of Inorganic Polymers and Geopolymers)
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16 pages, 4154 KiB  
Article
Chemical and Mechanical Properties of Metakaolin-Based Geopolymers with Waste Corundum Powder Resulting from Erosion Testing
by Giovanni Dal Poggetto, Pakamon Kittisayarm, Suphahud Pintasiri, Pongpak Chiyasak, Cristina Leonelli and Duangrudee Chaysuwan
Polymers 2022, 14(23), 5091; https://doi.org/10.3390/polym14235091 - 23 Nov 2022
Cited by 1 | Viewed by 1437
Abstract
Alkali activated binders, based on an aluminosilicate powder that is activated by an alkaline solution, have been proven to encapsulate a wide number of different wastes, both in the form of liquids and solids. In this study, we investigated the effect that the [...] Read more.
Alkali activated binders, based on an aluminosilicate powder that is activated by an alkaline solution, have been proven to encapsulate a wide number of different wastes, both in the form of liquids and solids. In this study, we investigated the effect that the addition of a spent abrasive powder, mainly composed of corundum grains (RC), had on the mechanical, physical, and chemical properties of metakaolin-based geopolymers. The waste was introduced into the geopolymer matrix as a substitute for metakaolin, or added as a filler to the geopolymeric paste. The 3D cross-linking of the geopolymer structure, with and without the presence of the corundum, was investigated via Fourier transform infrared spectroscopy, X-ray diffraction, and ionic conductivity measurements of the eluate that was produced after 24 h of immersion of the sample in water. The RC powder did not significantly modify the matrix reticulation but increased densification, as observed with scanning electron microscopy, and there was increased resistance to compression by 10 wt% addition of RC, and also when added to the paste as a filler at 20 wt%. Full article
(This article belongs to the Special Issue Development of Inorganic Polymers and Geopolymers)
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13 pages, 5977 KiB  
Article
Characterisation of White Metakaolin-Based Geopolymers Doped with Synthetic Organic Dyes
by Antonio D’Angelo, Giovanni Dal Poggetto, Simona Piccolella, Cristina Leonelli and Michelina Catauro
Polymers 2022, 14(16), 3380; https://doi.org/10.3390/polym14163380 - 18 Aug 2022
Cited by 7 | Viewed by 1350
Abstract
Over the years, many materials have been used to restore buildings, paintings, ceramics, and mosaic pieces exhibiting different types of dyes and colour hues. Recently, geopolymers have been used for restoration purposes owing to their high chemical and mechanical resistance. In this work, [...] Read more.
Over the years, many materials have been used to restore buildings, paintings, ceramics, and mosaic pieces exhibiting different types of dyes and colour hues. Recently, geopolymers have been used for restoration purposes owing to their high chemical and mechanical resistance. In this work, white metakaolin was used to obtain white geopolymers, cured at 25 and 40 °C, as bulk materials to be coloured with synthetic organic dyes, i.e., bromothymol blue, cresol red, phenolphthalein, and methyl orange. These dyes were added during the fresh paste preparation to obtain dyed geopolymeric solids. Ionic conductivity and pH measurement confirmed the chemical stability of the consolidated materials, while FT-IR analyses were used to follow the geopolymerisation occurrences at different ageing times (from 7 to 56 days). Finally, the colour hues and properties were assessed in the CIELAB colour space before and after immersion in water. Full article
(This article belongs to the Special Issue Development of Inorganic Polymers and Geopolymers)
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Review

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37 pages, 1840 KiB  
Review
Phase Change Material Evolution in Thermal Energy Storage Systems for the Building Sector, with a Focus on Ground-Coupled Heat Pumps
by Silvia Barbi, Francesco Barbieri, Simona Marinelli, Bianca Rimini, Sebastiano Merchiori, Michele Bottarelli and Monia Montorsi
Polymers 2022, 14(3), 620; https://doi.org/10.3390/polym14030620 - 5 Feb 2022
Cited by 11 | Viewed by 5973
Abstract
The building sector is responsible for a third of the global energy consumption and a quarter of greenhouse gas emissions. Phase change materials (PCMs) have shown high potential for latent thermal energy storage (LTES) through their integration in building materials, with the aim [...] Read more.
The building sector is responsible for a third of the global energy consumption and a quarter of greenhouse gas emissions. Phase change materials (PCMs) have shown high potential for latent thermal energy storage (LTES) through their integration in building materials, with the aim of enhancing the efficient use of energy. Although research on PCMs began decades ago, this technology is still far from being widespread. This work analyses the main contributions to the employment of PCMs in the building sector, to better understand the motivations behind the restricted employment of PCM-based LTES technologies. The main research and review studies are critically discussed, focusing on: strategies used to regulate indoor thermal conditions, the variation of mechanical properties in PCMs-based mortars and cements, and applications with ground-coupled heat pumps. The employment of materials obtained from wastes and natural sources was also taken in account as a possible key to developing composite materials with good performance and sustainability at the same time. As a result, the integration of PCMs in LTES is still in its early stages, but reveals high potential for employment in the building sector, thanks to the continuous design improvement and optimization driven by high-performance materials and a new way of coupling with tailored envelopes. Full article
(This article belongs to the Special Issue Development of Inorganic Polymers and Geopolymers)
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