29Si and 27Al NMR study of the structural transformation of calcined kaolin residue-based geopolymer using low alkali activator content for sustainable construction materials

Prasanphan, Sitthisak; Hemra, Khanthima; Wannagon, Anucha; Kobayashi, Takaomi; Onutai, Sujitra; Jiemsirilers, Sirithan

doi:10.1016/j.jobe.2023.106332

Cited by 9 publications

(3 citation statements)

References 33 publications

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“…In addition, the effect of the relative activation agent ratio (hydroxide:silicate) of 3.00 and 0.33 varied between the uncarbonated (FGT) and carbonated (CO 2 FGT) series. It is well known that, generally, a higher dose of Si (lower hydroxide:silicate ratio) contributes significantly to compressive strength [ 59 ]. However, it can be seen that after mineral carbonation, a higher dose of hydroxide favors an increase in compressive strength.…”

Section: Resultsmentioning

confidence: 99%

Decarbonatization of Energy Sector by CO2 Sequestration in Waste Incineration Fly Ash and Its Utilization as Raw Material for Alkali Activation

Mokrzycki,

Baran,

Gazda-Grzywacz

et al. 2023

Materials

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In this study, municipal solid waste incineration (MSWI) fly ash was subjected to mineral carbonation with the aim of investigating CO2 sequestration in waste material. The conducted study follows the trend of searching for alternatives to natural mineral materials with the ability to sequestrate CO2. The mineral carbonation of MSWI fly ash allowed for the storage of up to 0.25 mmol CO2 g−1. Next, both carbonated and uncarbonated MSWI fly ashes were activated using an alkaline activation method by means of two different activation agents, namely potassium hydroxide and potassium silicate or sodium hydroxide and sodium silicate. Mineral carbonation caused a drop in the compressive strength of alkali-activated materials, probably due to the formation of sodium and/or potassium carbonates. The maximum compressive strength obtained was 3.93 MPa after 28 days for uncarbonated fly ash activated using 8 mol dm−3 KOH and potassium hydroxide (ratio 3:1). The relative ratio of hydroxide:silicate also influenced the mechanical properties of the materials. Both carbonated and uncarbonated fly ashes, as well as their alkali-activated derivatives, were characterized in detail by means of XRD, XRF, and FTIR. Both uncarbonated and carbonated fly ashes were subjected to TG analysis. The obtained results have proved the importance of further research in terms of high-calcium fly ash (HCFA) utilization.

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Section: Resultsmentioning

confidence: 99%

Decarbonatization of Energy Sector by CO2 Sequestration in Waste Incineration Fly Ash and Its Utilization as Raw Material for Alkali Activation

Mokrzycki,

Baran,

Gazda-Grzywacz

et al. 2023

Materials

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“…Through infrared spectrum analysis, we found that the Si-O network structure of red mud may undergo depolymerization and then recombine into a new network structure. To verify this discovery and identify the depolymerization combination structure, chemical shifts and network structure changes in 29 Si/ 27 Al NM in the original red mud and alkali red mud were analyzed via solid-state NMR technology [47,48].…”

Section: Nuclear Magnetic Resonance Spectroscopy Analysismentioning

confidence: 99%

Analysis of Alkali in Bayer Red Mud: Content and Occurrence State in Different Structures

Wang,

Jing,

Zhang

et al. 2023

Sustainability

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The application of large amounts of red mud in the field of building materials is one of the main ways to reuse this material, but the high alkali content of red mud limits its application. In this paper, the washable alkali, removable alkali, and lattice alkali contents of Bayer red mud were studied, and the occurrence states of potassium and sodium in red mud were studied using XRD, IR, XPS, and NMR. On this basis, the removal mechanism for potassium and sodium in red mud was analyzed. The results showed that the Na in the red mud was mainly deposited in the shelf silicon voids of hydroxy sodalite (Na8(AlSiO4)6(OH)2(H2O)2) in the form of Si-O-Na or Al-O-Na. K is deposited in the shelf silico-oxygen void of potassium feldspar (KAlSi3O8) in the form of Si-O-K or Al-O-K. The washable Na and K contents of the mud were 13.7% and 4.47%; the alkali removal agent CaO removed 83.1% and 50.8% of Na and K in the red mud; and the lattice alkali Na and K contents were 3.20% and 44.8%, respectively. In the process of red mud dealkalization, Ca2+ ions can enter the internal voids of the hydroxyl sodalite and potassium feldspar silica skeleton and then replace Al3+ in the Si-O skeleton and Na+ and K+ in the skeleton voids. The replacement reaction changes the silica tetrahedron network structure, resulting in the disintegration of the frame-like silica tetrahedron in the hydroxyl sodalite and potassium feldspar, forming an isolated, island-like silica tetrahedron in hydrated garnet.

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“…Globally, the cement industry accounts for approximately 10% of total CO 2 emissions [35]. With the global drive to reduce carbon emissions, the geopolymers have received increasing attention as a suitable alternative to OPC due to their reduced environmental impact [36,37]. In particular, the EM as raw materials for the geopolymers makes effective use of these wastes and reduces the environmental burden of waste disposal.…”

Section: Introductionmentioning

confidence: 99%

Eco-efficient recycling of engineering muck for manufacturing low-carbon geopolymers assessed through LCA: Exploring the impact of synthesis parameters of the performance

Yuan,

Liang,

Huang

et al. 2024

Preprint

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The construction industry's excessive reliance on cement has led to significant environmental concerns. With the push towards global low-carbon and sustainable development goals, there is an urgent need to find building materials that can replace cement. In this study, engineering muck (EM) produced by foundation pit engineering in subtropical area was used as raw material. The properties of EM were activated by pre-treatment methods to prepare low-carbon geopolymers. This study investigated the effects of synthesis parameters (SiO2/Na2O ratio and liquid-solid ratio) on the performance of the alkaline activated EM-based geopolymers. The results showed that the geopolymer with a SiO2/Na2O ratio of 1.5 achieved the highest compressive strength of 40 MPa in 7 days, exhibiting the densest structure and fewest cracks. In addition to also having the smallest pore sizes and highest thermal stability, indicating optimal pore structure for minimizing evaporation. This study showed that increasing the liquid-solid ratio refined the pore structure, but increased carbonate formation and mass loss at elevated temperatures. Moreover, a life cycle assessment (LCA) was used to compare the cradle-to-gate environmental impacts of the EM-based geopolymers and cement concretes, including global warming and acidification. The LCA demonstrated the CO2 and SO2 emissions of EM-based geopolymers were reduced by 4–26% and 8–19%, respectively, compared to concrete. This study suggests the use of alkaline activation technology to transform the EM into the geopolymers should be expected to become a substitute for concrete, providing a new type of green building material for the geotechnical engineering.

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29Si and 27Al NMR study of the structural transformation of calcined kaolin residue-based geopolymer using low alkali activator content for sustainable construction materials

Cited by 9 publications

References 33 publications

Decarbonatization of Energy Sector by CO2 Sequestration in Waste Incineration Fly Ash and Its Utilization as Raw Material for Alkali Activation

Decarbonatization of Energy Sector by CO2 Sequestration in Waste Incineration Fly Ash and Its Utilization as Raw Material for Alkali Activation

Analysis of Alkali in Bayer Red Mud: Content and Occurrence State in Different Structures

Eco-efficient recycling of engineering muck for manufacturing low-carbon geopolymers assessed through LCA: Exploring the impact of synthesis parameters of the performance

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