Control of the alumino-silico-phosphate geopolymers properties and structures by the phosphorus concentration

Mathivet, Virginie; Jouin, Jenny; Parlier, M.; Rossignol, Sylvie

doi:10.1016/j.matchemphys.2020.123867

Cited by 11 publications

(13 citation statements)

References 29 publications

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“…When the W/M ratio is increased to 0.40, the strength of the MKPG reaches 57.6 MPa, which is 32.6 % higher than that of the samples with a W/M ratio of 0.35: however, at higher W/M ratios, the compressive strength decreases, in a manner that is quasi-proportional to the W/M ratio. This trend is in agreement with the literature [18]. As the W/M ratio is increased to 0.65, the compressive strength decreases to 23.0 MPa.…”

Section: Compressive Strengthsupporting

confidence: 93%

“…This phenomenon implies that excess water is present in MKPGs as water rather than as absorbed water leading to the formation of hydrated phases or physicallyabsorbed phases. The free water loss increases the porosity of the MKPGs, which might be another reason resulting in a decrease in the compressive strength [18]. The physically-or chemically-adsorbed water is almost the same in the Ew-series specimens with the different W/M ratios.…”

Section: Water Lossesmentioning

confidence: 96%

“…As the W/M ratio is increased to 0.65, the compressive strength decreases to 23.0 MPa. Mathivet et al [18] concluded that the water plays two roles in the processes of geopolymerisation: 1) decreasing the viscosity and thus promoting the reaction of the medium; and 2) diluting the concentration of the reactive species and possibly degrading the chemical potential. Therefore, an appropriate amount water is necessary to achieve the most effective geopolymerisation process.…”

Section: Compressive Strengthmentioning

confidence: 99%

“…Above 240 °C, the water losses are less than 1.0 % and vary slightly, regardless of the W/K ratio. The water losses at 110 °C (and beyond) are associated with the physically-absorbed water and the dehydration of the hydrated phases or the chemical-adsorbed water [18,23].…”

Section: Water Lossesmentioning

confidence: 99%

“…During the dissolution of MK, it is essential to adjust the water to control the degree of polymerisation of the phosphoric acid, which will control the polycondensation reaction [17]. The amount of water affects the setting time and viscosity of the mixture, further influencing the structural phases and mechanical properties of MKGPs [18]. In addition, the residual water in the calcined kaolin is another factor influencing such geopolymeric processes.…”

Section: Introductionmentioning

confidence: 99%

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The Effect of Water on Metakaolin Phosphate-Based Geopolymer Properties

Tian¹

2022

Ceramics - Silikaty

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The work deals with the synthesis of metakaolin phosphate-based geopolymers (MKPGs) using calcined kaolin, phosphoric acid (PA), and mixing water. The metakaolin was thermally treated at 750 °C for different holding times. The different duration in the heating at 750 °C led to the gradual dehydroxylation of kaolin to metakaolin with a different structural water content (inter-layer and inner-layer residual water). Considering the temperature or duration of the thermal dehydroxylation, the inter-layer water evolved first, followed by the inner-layer water at a higher temperature or later time. The polymerisation degree is closely linked with the presence of the inter-or inner-layer water. It was found that the inter-layer residual water negatively influences the compressive strength, while the water in the inner-layer exerts a more negligible effect on the resistance. Indeed, the inter-layer water loss is linked to the structural changes in kaolinite; but the loss of water from the inner-layer is related to the structural changes in the metakaolinite. The holding time of dehydroxylation and waterto-metakaolin (W/M) ratio were optimised. A maximum strength of 57.6 MPa was achieved at the Al/P and W/M ratios of 1.0 and 0.40, respectively. The mass losses at the different temperatures showed that the additional excess mixing water increased the porosity of the MKPGs, resulting in a decrease in the compressive strength.

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Section: Compressive Strengthsupporting

confidence: 93%

Section: Water Lossesmentioning

confidence: 96%

Section: Compressive Strengthmentioning

confidence: 99%

Section: Water Lossesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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