Porous structure optimisation of flash-calcined metakaolin/fly ash geopolymer foam concrete

Samson, Gabriel; Cyr, Martin

doi:10.1080/19648189.2017.1304285

Cited by 29 publications

(19 citation statements)

References 24 publications

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“…Geopolymers can be a viable alternative to concretes based on Portland cement mainly due to the reduced CO 2 emissions (compared to OPC) [79,80]. The authors of [81] presented the results confirming that the CO 2 -e emission of geopolymer concrete is 9% less than OPC, despite the fact that many scientists previously claimed that it was a greater reduction value.…”

Section: Forecast and Summarymentioning

confidence: 98%

Geopolymer Foams—Will They Ever Become a Viable Alternative to Popular Insulation Materials?—A Critical Opinion

Łach

2021

Materials

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Over the last several years, there has been a large increase in interest in geopolymer materials, which are usually produced from waste materials, and their applications. The possibilities of application of geopolymers seem to be unlimited, and they are used in almost all fields of technology. Their use as insulation materials appears promising due to their complete nonflammability and excellent strength. However, one limitation is their complex manufacturing process and lack of stability of the obtained geopolymer foams as well as difficulties in achieving such good insulation properties possessed by polyurethane foams, polystyrene, and wool. Hundreds of studies have already been performed on insulating geopolymer foams and various types of foaming agents, and their authors reported that foamed insulating geopolymers had a density starting from 200 kg/m3 and thermal conductivity from 0.04 W/mK. However, the repeatability of the obtained results on an industrial scale is questionable. It is still a challenge to obtain a geopolymer material with comparable properties as conventional insulation materials and to overcome the barriers associated with the successful implementation of geopolymer material as insulation in buildings and other applications on a mass scale. This paper provides a comprehensive review of the methods used for the production of foamed geopolymers and the best parameters obtained, as well as a summary of the most important information reported in the scientific literature. It also presents the results of a critical analysis of the feasibility of implementing this technology for mass deployment. In addition, the problems and limitations that are most often encountered with the implementation of geopolymer technology are discussed.

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Section: Forecast and Summarymentioning

confidence: 98%

Geopolymer Foams—Will They Ever Become a Viable Alternative to Popular Insulation Materials?—A Critical Opinion

Łach

2021

Materials

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“…Equations: H 2 O 2 + OH − ⟶ HO 2 − + H 2 O, and HO 2 − + H 2 O 2 ⟶ H 2 O + O 2 + OH − , represent the reactions during the foam formation [45]. It has been suggested that if the amount of H 2 O 2 is too high, the pores were not well distributed because of the bubble’s buoyancy [46]. Indeed, the effect of random distribution of the pores was observed for G and GM foams.…”

Section: Resultsmentioning

confidence: 99%

“…Additionally, the coalescence of macropores observed in the G and GM foams can cause a decrease in the flexural strength found in these samples. Third, the presence of small cracks in the G foam (but not in GC) exposed to the acidic agent, can further increase the susceptibility of the basic geopolymer foams G. Fourth, the strength of the geopolymer material depends on the matrix strength [46]. Uniform dispersion of cotton fibres in the slurry could result in an improvement of the consistency of the matrix as well as high wettability between the fibres and the paste during the geopolymerisation process.…”

Section: Resultsmentioning

confidence: 99%

Optimal Design of pH-neutral Geopolymer Foams for Their Use in Ecological Plant Cultivation Systems

et al. 2019

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We have calculated that with the world population projected to increase from 7.5 billion in 2017 to 9.8 in 2050, the next generation (within 33 years) will produce 12,000–13,000 Mt of plastic, and that the yearly consumption will reach 37–40 kilos of plastic per person worldwide. One of the branches of the plastics industry is the production of plastics for agriculture e.g., seed trays and pots. In this paper, novel metakaolin-based geopolymer composites reinforced with cellulosic fibres are presented as an alternative to plastic pots. Materials can be dedicated to agricultural applications, provided they have neutral properties, however, geopolymer paste and its final products have high pH. Therefore, a two-step protocol of neutralisation of the geopolymer foam pots was optimised and implemented. The strength of the geopolymer samples was lower when foams were neutralised. The reinforcement of geopolymers with cellulose clearly prevented the reduction of mechanical properties after neutralisation, which was correlated with the lower volume of pores in the foam and with the cellulose chemical properties. Both, neutralisation and reinforcement with cellulose can also eliminate an efflorescence. Significantly increased plant growth was found in geopolymer pots in comparison to plastic pots. The cellulose in geopolymers resulted in better adsorption and slower desorption of minerals during fertilisation. This effect could also be associated with a lower number of large pores in the presence of cellulose fibres in pots, and thus more stable pore filling and better protection of internal surface interactions.

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“…The composition was expanded using H 2 O 2 in amounts of 1, 1.5, and 2 wt.% and densities from 225 to 506 kg/m 3 and thermal conductivities from 0.07 to 0.12 W/mK were obtained. These studies have also shown that the use of surfactants has a huge impact on the porous structure [8]. It is also possible to use rice husks as a foaming agent [9].…”

Section: Introductionmentioning

confidence: 99%

“…To obtain the optimal parameters of the geopolymer foams, the metakaolin and fly ash are often used together. Samson and Cyr [8] proved that the most optimal composition for their type of raw materials was 62.5% metakaolin with 12.5% fly ash and 25% activator. The composition was expanded using H 2 O 2 in amounts of 1, 1.5, and 2 wt.% and densities from 225 to 506 kg/m 3 and thermal conductivities from 0.07 to 0.12 W/mK were obtained.…”

Section: Introductionmentioning

confidence: 99%

Development and Characterization of Thermal Insulation Geopolymer Foams Based on Fly Ash

Łach

Mikuła

Lin

et al. 2020

Proc. eng. technol. innov.

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The main purpose of the article is to present the differences in the parameters of geopolymer foams obtained in the same way, which is associated with difficulties in controlling the foaming process. Difficulties in controlling the foaming process of geopolymers are the direct reason for the lack of implementation of such materials nowadays. The article shows the results for experimental research, especially research into insulation, physical, and mechanical properties for the designated foamed materials. Microspheres (75%), sand (5%) and fly ash (20%) were used to produce foamed geopolymers. Hydrogen peroxide was the foaming agent. Heat conduction coefficients of 0.08-0.07 W/mK were obtained. The material density was obtained at the level of 363-375 [kg/m3] and the compressive strength was 520-683 [kPa]. The results showed that geopolymers can be a good alternative to conventional insulation materials, but the foaming technology should be developed so that it is stable and allows for reproducible material parameters.

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Porous structure optimisation of flash-calcined metakaolin/fly ash geopolymer foam concrete

Cited by 29 publications

References 24 publications

Geopolymer Foams—Will They Ever Become a Viable Alternative to Popular Insulation Materials?—A Critical Opinion

Geopolymer Foams—Will They Ever Become a Viable Alternative to Popular Insulation Materials?—A Critical Opinion

Optimal Design of pH-neutral Geopolymer Foams for Their Use in Ecological Plant Cultivation Systems

Development and Characterization of Thermal Insulation Geopolymer Foams Based on Fly Ash

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