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Query: "keywords" (alkali-activated material) .

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11.
Microwave irradiation of alkali - activated metakaolin slurry
Barbara Horvat, Branka Mušič, Majda Pavlin, Vilma Ducman, 2023, published scientific conference contribution

Abstract: The building and civil engineering industry generates more than 40% of man-caused carbon emissions, consumes a lot of energy just to produce building materials, generates a large amount of waste through construction and demolition, and consumes a large amount of natural resources. One of the possible solutions is to use alkali-activated materials, which can use waste instead of raw materials and are produced at lower temperatures, with less energy consumption and in less time than traditional building products. All of this lowers the carbon footprint, which could be further reduced by the timely-short implementation of microwave irradiation in the early stages of alkali-activation synthesis. Therefore, metakaolin activated with Na-water glass in a theoretically optimal ratio was irradiated with microwaves of 2.45 GHz at powers of 100 W and 1000 W for 1 min, and compared to non-irradiated reference cured only at room conditions. Samples prepared at higher power, i.e., 1000 W, solidified completely and foamed. TG-DTA was performed on all samples in the early stages of curing, mechanical strengths were measured on 3 and 28-day- old samples, and leaching tests on aged samples.
Keywords: metakaolin, alkali activated material, alkali activated foams, microwave irradiation
Published in DiRROS: 28.11.2023; Views: 269; Downloads: 111
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12.
Influence of microwaves in the early stage of alkali activation on the mechanical strength of alkali-activated materials
Barbara Horvat, Majda Pavlin, Vilma Ducman, 2023, original scientific article

Abstract: This study focuses on the influence of microwave irradiation dosimetry on alkali-activated slurry in its early stages. The impact on the chemistry and mineralogy along with the mechanical properties were evaluated by changing the power of microwaves and their duration of exposure. This influenced the dissolution of amorphous content, diffusion, and self-assembly into an aluminosilicate network. The precursors used in this study were metakaolin, a non-waste material commonly used in geopolymerisation technology, and local fly ash and ladle furnace slag as secondary materials. Furthermore, they were chemically and mineralogically analysed, and their mixtures with NaOH and Na-water glass provided the optimal ratio of the amount of elements obtained using the pre-calculation approach. However, the potential extra addition of water was experimentally determined to allow complete wetting of the material and solid workability during moulding. Using Fourier-transform infrared spectroscopy, the influence of water was further investigated in alkali-activated slag and fly ash irradiated with microwaves, which resulted in the highest values of mechanical strength in the dosimetry-mapping part of the analysis. In addition to the time dependence of the expected mechanical strength on the ageing of the alkali- activated material, the synthesised material exhibited a significant dependence on the dose of microwave irra- diation, which was different for every precursor as well as every mixture with different chemistries.
Keywords: odpadni material, alkalijska aktivacija, obsevanje z mikrovalovi, mehanska trdnost, waste material, alkali activation, microwave irradiation, mechanical strength
Published in DiRROS: 12.07.2023; Views: 397; Downloads: 290
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