A comparative study of geopolymers synthesized from OXY-combustion and chemical looping combustion bottom ashes

Nkuna, Clara; Oboirien, Bilainu; Sadiku, Rotimi; Lekitima, Joel N.

doi:10.1016/j.conbuildmat.2017.01.035

Cited by 7 publications

(5 citation statements)

References 17 publications

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“…thermal resistance, reaching up to 1200 °C. The optimal geopolymer calcined at 1200 °C showed the highest resistance to a compressive strength of 74.20 kg f /cm 2 , exceeding the reference value for refractory material indicated in the ASTM C133-97 [11] standard that should support 30.60 kg f /cm 2 . This result indicates a potential for use in refractory construction.…”

Section: Conflict Of Interestmentioning

confidence: 74%

“…A geopolymer is an alkali‐activated synthetic inorganic aluminosilicate that can produce a Si−O−Al structure, which reacts and sets rapidly at low temperatures, resulting in a hard and stable product at elevated temperatures up to 1250 °C [2] . The structure of geopolymers is a network of Si‐O−Al bonds made up of tetrahedra of (Si iv O 4 ) −4 and (Al iv O 4 ) −4 linked alternately [3] .…”

Section: Introductionmentioning

confidence: 99%

“…A geopolymer is an alkali-activated synthetic inorganic aluminosilicate that can produce a SiÀ OÀ Al structure, which reacts and sets rapidly at low temperatures, resulting in a hard and stable product at elevated temperatures up to 1250 °C. [2] The structure of geopolymers is a network of Si-OÀ Al bonds made up of tetrahedra of (Si iv O 4 ) À 4 and (Al iv O 4 ) À 4 linked alternately. [3] Aluminum has a coordination number of four (Al iv ) in relation to oxygen, creating an unbalanced negative charge and the presence of cations, such as K + , Na + , and Ca + 2 , which are essential to maintain the electrical neutrality of the matrix.…”

Section: Introductionmentioning

confidence: 99%

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Obtaining a Refractory Geopolymer Based on Clays and Seashells

et al. 2022

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The synthesis of a refractory geopolymer with excellent thermal and mechanical properties to develop materials that resist temperatures above 1000 °C has become a challenge in recent years. The production of a refractory material involves the combination of clays and alkaline substances, whose formulation produces an improvement in the final properties of the refractory material. In this work, we report a Taguchi L18 design to synthesize a refractory geopolymer that exhibits the highest compressive strength, based on two natural clays from Mexico, seashells, sodium silicate and water. The prepared mixture was molded to form mini bricks, which were cured for 24 hours at room temperature. Subsequently, the bricks were dried for 4 days, and we evaluated the effect of temperature at 40 °C, 60 °C and 80 °C. Subsequently, the samples were subjected to calcination between 900 °C and 1200 °C to determine the resistance to both thermal and mechanical fracture via compression. The highest thermal resistance and compressive strength were obtained with a geopolymer formulated with 7.5 % seashells, 38.2 % Tepozán‐Bauwer clay, 30.0 % Kaolin clay, 20 % commercial sodium silicate and 4.3 % water, which was dried at 40 °C. The compressive strength was 7.28 MPa (74.2 kgf /cm2), and the thermal resistance was up to 1200 °C. In the FTIR analysis of the geopolymers calcined at 1200 °C, the influence of calcium was observed by the bands of the 800–1200 cm−1 region, where there was a greater distribution since the Si−O− bond was added. Ca was found at 950 cm−1. By adding CaCO3 in the form of seashells, the presence of the anorthite mineral phase (CaAl2Si2O8) can be identified, which originates from the degradation of calcium carbonate crystals (calcite, vaterite and aragonite) of the identified seashells using XRD. The synthesized geopolymer has potential use in the refractory and ceramic materials industry.

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Section: Conflict Of Interestmentioning

confidence: 74%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Obtaining a Refractory Geopolymer Based on Clays and Seashells

et al. 2022

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“…8). For geopolymers made of M1 or M2 metakaolin, multiple bondings in the 460-465 cm -1 range indicate the presence of Si-O-Si, Si-O-Al or O-Si-O bending vibrations, whereas in the 550-1159 cm -1 region, Si-O-Si or Si-O-Al symmetrical stretching vibrations were found [30][31][32]. In addition, these materials exhibit weak effects at 3419 cm -1 , which correspond to O-H stretching vibrations.…”

Section: Resultsmentioning

confidence: 99%

Thermal phenomena of alkali-activated metakaolin studied with a negative temperature coefficient system

Mierzwiński

Łach

Hebda

et al. 2019

J Therm Anal Calorim

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The properties of alkali-activated materials (AAMs) depend on both the type of raw material used and their production procedure. This article presents an inexpensive and easily accessible method, based on using thermistors with a negative temperature coefficient, to analyse phenomena during the geopolymerisation process of AAMs. The described method enables prediction of the final physical and mechanical properties of tested materials and allows unambiguous determination of the quality of raw metakaolin materials in terms of their suitability for geopolymerisation processes and AAM production. This statement was proved by comparing AAMs formed based on metakaolin from three different sources. This article also describes the results of the mineralogical analysis, density, particle size distribution and morphology of the three metakaolins. In addition, the compression strength and FT-Raman spectroscopy of the AAM produced are described. Even though all materials were referred to as metakaolin, the results of this study showed that calcined materials can significantly differentiate the geopolymerisation process and final physical and mechanical properties of AAM.

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“…Other bottom ashes, different from incinerator ones, but rich in silica and alumina, have been successfully used in the geopolymer formulation, such as bottom ash from a thermal power plant [35], circulating fluidized bed combustion bottom ash [36][37][38], bagasse bottom ash [39], lignite bottom ash [40] and OXY-combustion and chemical looping combustion bottom ashes [41].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of Biochar-Based Geopolymer Materials

et al. 2021

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The aim of this research is to evaluate the possibility to realize alkali-activated materials exploiting biochar, a secondary raw material coming from pyrolysis/gasification processes, for environmental benefits, such as improvement of soil fertility and reduction of CO2 emissions into the atmosphere thanks to the carbon sink process where carbon dioxide is subtracted from the cycle of carbon. For the matrix of the geopolymers, a waste material derived from incinerator bottom ash was used and compared to pure metakaolin matrix. The materials obtained are lightweight and porous, with high water absorption capacity and moisture adsorption/desorption. BET analysis shows an increase in specific surface by increasing the biochar content and the biochar acts as a filler in the pores. From porosimetry analysis it is possible to follow the evolution of the curing process of the geopolymer prepared: specimens containing 70 wt% biochar after 28 and 90 days showed an increase in total Hg intrusion volume, pore area and total porosity but a decrease in the dimensions of pores. Due to the technical properties of materials containing biochar, they can be used in the future for a cleaner design of products in the field of sustainable construction for insulating panels or lightweight materials for houses and gardens in terraces and balconies.

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A comparative study of geopolymers synthesized from OXY-combustion and chemical looping combustion bottom ashes

Cited by 7 publications

References 17 publications

Obtaining a Refractory Geopolymer Based on Clays and Seashells

Obtaining a Refractory Geopolymer Based on Clays and Seashells

Thermal phenomena of alkali-activated metakaolin studied with a negative temperature coefficient system

Synthesis and Characterization of Biochar-Based Geopolymer Materials

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