High temperature resistant fly-ash and metakaolin-based alkali-activated foams

Traven, Katja; Češnovar, Mark; Škapin, Srečo D.; Ducman, Vilma

doi:10.1016/j.ceramint.2021.05.241

Cited by 40 publications

(10 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A solution of hydrogen peroxide, H 2 O 2 , with a concentration of 30 vol% was used as the foaming agent (produced by Carlo Erba Reagents, Cornaredo, Italy) and sodium dodecyl sulphate (SDS; produced by Acros organics) as a surfactant. Mixtures were developed and presented in detail in a previous paper by Traven et al (2021 ), and compositions of samples selected for this study are given in Table 1 . All lightweight alkali-activation foams were foamed with 1 mass% of H 2 O 2 , and pores were stabilized with the addition of 1 mass% of sodium dodecyl sulfate as a surfactant.…”

Section: Methodsmentioning

confidence: 99%

“…For the alkali activation, two types of powder precursors were used, FA obtained from a Slovenian thermal plant and metakaolin (MK) from company Argeco, Fumel, France. The main constituents of the fly ash are as follows: 44.8 wt% SiO 2 , 22.9 wt% Al 2 O 3 , 12.4 wt% CaO,and 10.7 Traven et al (2021), and compositions of samples selected for this study are given in Table 1. All lightweight alkali-activation foams were foamed with 1 mass% of H 2 O 2 , and pores were stabilized with the addition of 1 mass% of sodium dodecyl sulfate as a surfactant.…”

Section: Experimental Materialsmentioning

confidence: 99%

“…Density as low as 0.3 g/cm 3 could be achieved by this method, whereas porosity significantly influences mechanical performance. A thermal post-treatment of the AAFs by exposing such foams to high temperature between 800°C and 1,000°C can be implemented without affecting density too much ( Monich et al, 2018 ; Bajare et al, 2019 ; Traven et al, 2021 ).…”

Section: Introductionmentioning

confidence: 99%

“…The aim of the present study was to assess environmental performance of AAF whose technical properties are described in paper by Traven et al (2021 ). The high porosity of such foams could be critical in terms of cation exchange with natural environment; thus, an accurate bio-impact is beneficial to ascertain their safe use and durability.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Environmental and Biological Impact of Fly Ash and Metakaolin-Based Alkali-Activated Foams Obtained at 70°C and Fired at 1,000°C

et al. 2022

Self Cite

View full text Add to dashboard Cite

Alkali-activated foams (AAFs) are inorganic porous materials that can be obtained at temperatures well below 100°C with the use of inorganic wastes as aluminosilicate precursors. In this case, fly ash derived from a Slovenian power plant has been investigated. Despite the environmental benefits per se, due to saving of energy and virgin materials, when using waste materials, it is of extreme importance to also evaluate the potential leaching of heavy metal cations from the alkali-activated foams. This article presents an environmental study of a porous geopolymer derived from this particular fly ash, with respect to the leachability of potentially hazardous elements, its environmental toxicity as determined by biological testing, and the environmental impact of its production. In particular, attention was focused to investigate whether or not 1,000°C-fired alkali-activated fly ash and metakaolin-based foams, cured at 70°C, are environmentally friendlier options compared to unfired ones, and attempts to explain the rationale of the results were done. Eventually, the firing process at 1,000°C, apart from improving technical performance, could reinforce heavy metal cation entrapment within the aluminosilicate matrix. Since technical performance was also modified by addition of different types of activators (K-based or Na-based), as well as by partial replacement of fly ash with metakaolin, a life cycle assessment (LCA) analysis was performed to quantify the effect of these additions and processes (curing at 70°C and firing at 1,000°C) in terms of global warming potential. Selected samples were also evaluated in terms of leaching of potentially deleterious elements as well as for the immobilization effect of firing. The leaching test indicated that none of the alkali-activated material is classified as hazardous, not even the as-received fly ash as component of new AAF. All of the alkali-activated foams do meet the requirements for an inertness. The highest impact on bacterial colonies was found in samples that did not undergo firing procedures, i.e., those that were cured at 70°C, which induced the reduction of bacterial Enterococcus faecalis viability. The second family of bacteria tested, Escherichia coli, appeared more resistant to the alkaline environment (pH = 10–12) generated by the unfired AAMs. Cell viability recorded the lowest value for unfired alkali-activated materials produced from fly ash and K-based activators. Its reticulation is only partial, with the leachate solution appearing to be characterized with the most alkaline pH and with the highest ionic conductivity, i.e., highest number of soluble ions. By LCA, it has been shown that 1) changing K-based activators to Na-based activators increases environmental impact of the alkali-activated foams by 1%–4% in terms of most of the impact categories (taking into account the production stage). However, in terms of impact on abiotic depletion of elements and impact on ozone layer depletion, the increase is relatively more significant (11% and 18%, respectively); 2) replacing some parts of fly ash with metakaolin also results in relatively higher environmental footprint (increase of around 1%–4%, while the impact on abiotic depletion of elements increases by 14%); and finally, 3) firing at 1,000°C contributes significantly to the environmental footprint of alkali-activated foams. In such a case, the footprint increases by around one third, compared to the footprint of alkali-activated foams produced at 70°C. A combination of LCA and leaching/toxicity behavior analysis presents relevant combinations, which can provide information about long-term environmental impact of newly developed waste-based materials.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Experimental Materialsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Environmental and Biological Impact of Fly Ash and Metakaolin-Based Alkali-Activated Foams Obtained at 70°C and Fired at 1,000°C

et al. 2022

Self Cite

View full text Add to dashboard Cite

show abstract

“…At 500 °C, nepheline appears as a newly formed crystalline phase due to the partial crystallization of sodium aluminosilicate hydrate gel (N-A-S-H). Nepheline is one of the more porous crystalline phases that can adversely affect the compactness of the gel structure, resulting in a weaker gel structure [36,37]. Calcium in the samples is responsible for the formation of nepheline crystal structure after exposure to high temperatures [38].…”

Section: X-ray Diffraction (Xrd) Analysismentioning

confidence: 99%

The role of chemistry and fineness of metakaolin on the fresh properties and heat resistance of blended fly ash-based geopolymer

et al. 2023

View full text Add to dashboard Cite

Sensible thermal energy storage using concrete as a storage medium is a promising technology that helps minimize energy in power plant. The purpose of this study is to evaluate the potential benefits of metakaolin (MK) as a partial substitute for fly ash-based geopolymer for heat resistance. As a partial substitute (5 and 20 wt.%) for fly ash (FA), nine metakaolins containing different alumina contents were selected. In order to assess their potential for storing high-temperature thermal energy, physical and microstructural analyses were performed before and after heat exposure up to 500 °C. Low packing density limits the workability of some metakaolins and increases water demand in pastes. The mechanical properties of geopolymer weaken as the temperature is raised (< 500 °C). The high alumina content of some metakaolins, however, helps to mitigate strength loss during high temperatures. A higher dosage of metakaolin has also shown to prevent this deterioration of strength. A reduction in strength under heating is caused by both dehydration and dehydroxylation. The higher fineness and alumina content of MK have demonstrated significant potential to enhance the heat resistance of FA-based geopolymers. As a result, the geopolymer paste developed is suitable for being used in heat-resistant applications.Article Highlights Fly ash was the main precursor of as prepared alkali-activated binders. Adding metakaolin enhances the resistance of hardened materials under thermal load. The higher the alumina content inside metakaolin is, the higher the performance is.

show abstract

Fire resistance characteristics of geopolymer concrete for environmental sustainability: a review of thermal, mechanical and microstructure properties

Hassan

Arif

Shariq

et al. 2022

Environ Dev Sustain

View full text Add to dashboard Cite

High temperature resistant fly-ash and metakaolin-based alkali-activated foams

Cited by 40 publications

References 54 publications

Environmental and Biological Impact of Fly Ash and Metakaolin-Based Alkali-Activated Foams Obtained at 70°C and Fired at 1,000°C

Environmental and Biological Impact of Fly Ash and Metakaolin-Based Alkali-Activated Foams Obtained at 70°C and Fired at 1,000°C

The role of chemistry and fineness of metakaolin on the fresh properties and heat resistance of blended fly ash-based geopolymer

Fire resistance characteristics of geopolymer concrete for environmental sustainability: a review of thermal, mechanical and microstructure properties

Contact Info

Product

Resources

About