Development of precast geopolymer concrete via oven and microwave radiation curing with an environmental assessment

Kastiukas, Gediminas; Ruan, Shaoqin; Liang, Shuang; Zhou, Xiangming

doi:10.1016/j.jclepro.2020.120290

Cited by 88 publications

(21 citation statements)

References 45 publications

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“…However, the preparation of the commercial aerated products had an advantage over FAAG in terms of the energy consumption ( Figure 12), which could be attributed to the incorporation of alkali activator (i.e., NaOH and Na 2 SiO 3 ) in FAAG preparation, albeit its content is low. It is known that the production of these alkali involves the technique of electrolysis, which is an energyintensive process and leads to greater energy demand, and similar findings were also reported in our previous study (Kastiukas et al, 2020). In addition, Figure 12 also presented that if the environmental impacts of waste glass disposal via landfilling or incineration were avoided in the outcomes of FAAG, its CO 2 emission and energy consumption could be further reduced.…”

Section: Thermal Conductivitysupporting

confidence: 80%

“…Following the work from Kastiukas et al (2020), indicated that in the United Kingdom, due to the shutdown of the electricity plants and the upgrade of equipment in the steel industry, there will be a shortage of fly ash and ground-granulated blast-furnace slag soon, which are widely used as precursors in the preparation of geopolymers previously. Therefore, the waste glass would provide an alternative precursor for the preparation of samples, especially the foamed products.…”

Section: Discussionmentioning

confidence: 99%

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Waste Glass Reuse in Foamed Alkali-Activated Binders Production: Technical and Environmental Assessment

et al. 2020

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Waste glass is a type of construction and demolition waste, which carries significant environmental burdens and can be recycled. In this study, a foamed alkali-activated glass (FAAG) via the use of milled waste glass was synthesized in low-temperature (i.e., 80°C). The influence of foaming agent (i.e., aluminum powder) content on the foaming process of samples was investigated and optimized in view of their performance. The optimum mix formulation, which is FAAG with 10% aluminum powder was then selected, and followed by the measurement of the water-resistance and absorption, impact resistance and thermal conductivity of the prepared FAAG. X-ray diffraction was also involved to identify the phase formation within the samples. Finally, the environmental impacts related to the preparation of 1 kg FAAG were obtained. Results shows that a type of more sustainable FAAG compared with the commercial product was successfully developed in low-temperature, revealing the low thermal conductivity of ∼0.13 W/(mK) with a density of ∼0.59 g/cm 3 and compressive strength of ∼5.52 MPa, which is 97% higher than the commercial product. Meanwhile, in addition to a foaming agent, aluminum powder is also acting as a key component in the geopolymerization of samples, facilitating the formation of aluminosilicate that provides strength.

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Section: Thermal Conductivitysupporting

confidence: 80%

Section: Discussionmentioning

confidence: 99%

Waste Glass Reuse in Foamed Alkali-Activated Binders Production: Technical and Environmental Assessment

et al. 2020

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“…Even though each precursor has its peculiarities, due to the difference in chemical composition, reactivity, and particle size, there are reports of researchers studying the alkaline activation of fly ash, metakaolin, and blast furnace slag at room temperatures (25 to 30ºC) and in a greenhouse environment (60 to 90ºC). It was found that curing performed at a temperature of 60ºC considerably increases the compressive strength of the materials [28], [120], [121]. This increase in the cure temperature favors resistance because it increases the dissolution of reactive species, such as silica and alumina, increasing the reactions kinetics [122].…”

Section: Cure Type Influencementioning

confidence: 99%

Reaction mechanisms of alkali-activated materials

Marvila

Azevedo

Vieira

2021

Rev. IBRACON Estrut. Mater.

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The Alkali-Activated Materials (AAM) are defined as materials obtained through the reaction between precursors and activators, and are separated into two classes depending on the products formed in the reaction, those rich in calcium, as the blast furnace slag, whose Ca/(Si+Al) ratio is higher than 1; and poor in calcium, which is the geopolymers subclass. In this review article, some bibliographical aspects were discussed regarding the discovery of these materials, through research conducted by Victor Glukhovsky and through the characterization of historical monuments by Davidovits, which began in the 50s and 60s and persist to the present day. The main products obtained in the alkaline activation reaction were also addressed, using the definition of polysialates and zeolites, in the case of geopolymers, and the tobermorite structure, in the case of materials rich in calcium. The main steps of the alkali-activated reaction, such as dissolution, condensation, polycondensation, crystallization, and hardening, were discussed. Some techniques for characterizing the AA reaction products were also examined, such as X-ray diffraction (XRD), nuclear magnetic resonance spectrometry (NMR), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Finally, the main factors that interfere in the kinetics of AA reactions were explored, in which the type of cure and the activating solution used in the alkali-activated materials production stands out.

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“…Most importantly, the CO

emissions for producing one ton of geopolymer are only 20% of those for OPC [ 3 ]. The economical and environmental benefits would be further raised when geopolymers are synthesized with solid wastes with high value added applications [ 4 , 5 , 6 , 7 , 8 , 9 ]. The cementing or geopolymerization process of geopolymer precursors with alkaline activators can rapidly proceed to form a three-dimensional polymeric structure with complex Al-O-Si bonds and to generate continual material skeletons that enable high strengths [ 10 ].…”

Section: Introductionmentioning

confidence: 99%

Compositional Dependence of Pore Structure, Strengthand Freezing-Thawing Resistance of Metakaolin-Based Geopolymers

et al. 2020

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The understanding of the composition dependent properties and freezing-thawing (F-T) resistance of geopolymer materials is vital to their applications in cold regions. In this study, metakaolin-based geopolymer (MKG) mortars were fabricated by controlling the Si/Al ratio and the Na/Al ratio. The pore structure and strength were measured by mercury intrusion porosimetry and compression tests, respectively, which both showed obvious correlations with the material composition. Mass loss, strength loss, visual rate, and microscopic observation were adopted to assess the changes of the material properties and microstructure caused by F-T loads. The results showed that the strength-porosity relationship roughly followed a linear plot. Increases of the Si/Al ratio increased the capillary pore volume, but decreased the gel pore volume and the F-T resistance. Increases of the Na/Al ratio decreased the gel pore, but roughly enhanced the F-T resistance. The MKG mortar at the Na/Al ratio of 1.26 showed the lowest total pore volume and the best F-T resistance. The mechanisms of our experimental observations were that the abundantly distributed air voids connected by the capillary pores facilitated the relaxation of hydraulic pressures induced by the freezing of the pore liquid. The findings of this work help better clarify the compositional dependence of the pore structure, strength, and freezing-thawing resistance of MKG materials and provide fundamental bases for their engineering applications in cold regions.

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Development of precast geopolymer concrete via oven and microwave radiation curing with an environmental assessment

Cited by 88 publications

References 45 publications

Waste Glass Reuse in Foamed Alkali-Activated Binders Production: Technical and Environmental Assessment

Waste Glass Reuse in Foamed Alkali-Activated Binders Production: Technical and Environmental Assessment

Reaction mechanisms of alkali-activated materials

Compositional Dependence of Pore Structure, Strengthand Freezing-Thawing Resistance of Metakaolin-Based Geopolymers

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