Influence of the molar ratios CaO/SiO2 contained in the sustainable microcomposites on the mechanical and microstructural properties of (Ca, Na)-poly(sialate-siloxo) networks

Mabah, Dominique E. Tchinda; Tchakouté, Hervé K.; Fotio, Daniel; Rüscher, Claus H.; Kamseu, Elie; Bignozzi, Maria Chiara; Leonelli, Cristina

doi:10.1016/j.matchemphys.2019.121928

Cited by 12 publications

(10 citation statements)

References 26 publications

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“…It was demonstrated that the Ca/Si ratio has an effect on both the density and the specific area of the cementitious C-S-H. As the density increases with the increase in the molar ratio Ca/Si, the specific surface area will decrease (inverse relationship between the specific area and the Ca/Si molar ratio). 24,25 Similar structural results were observed by Mabah et al 25 Their work investigated the influence of the molar ratio CaO/SiO 2 (0, .4, .6, .8, 1.0, and 1.2) contained in the sustainable composites on the microstructural properties using sodium waterglass from rice husk ash and commercial sodium waterglass as chemical reagents. They confirmed that the lower amorphous calcium silicate hydrate content is related to the lower amount of SiO 2 in the structure of microcomposite.…”

Section: Structural Investigation Of Powder Mixtures and Final Cerami...supporting

confidence: 65%

Eco‐friendly preparation and structural characterization of calcium silicates derived from eggshell and silica gel

Kaou

Horváth

Balázsi

et al. 2022

Int J Applied Ceramic Tech

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In this work the preparation of calcium-silicate based composites consisting of natural waste from calcium source as eggshell and silica gel from desiccator as a silicon source both presenting alternative materials for cheap preparation of eco-friendly calciumsilicate bioceramics has been investigated. The effect of CaO/SiO 2 ratio on microstructural properties has also been studied. The pseudo-wollastonite formation has been observed in the case of 40 wt.% CaO and 60 wt.% SiO 2 with lowest porosity and highest density 2.6 g/cm 3 . In the case of 50 wt.% CaO and 50 wt.% SiO 2 the phase transformation from pseudo-wollastonite to wollastonite was observed. Increasing the calcium content caused higher apparent porosity with 19%. It was shown that the development of novel ceramics from reused waste, eggshell or silica can be an optimal solution for low-cost preparation of calcium silicates with potential applications in medicine or cement, food industry.

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Section: Structural Investigation Of Powder Mixtures and Final Cerami...supporting

confidence: 65%

Eco‐friendly preparation and structural characterization of calcium silicates derived from eggshell and silica gel

Kaou

Horváth

Balázsi

et al. 2022

Int J Applied Ceramic Tech

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“…Thus, a technology based on “alkali-activation” for gel formation could completely substitute the requirements of using alite and belite. At this point, we may refer to some investigations and more references therein concerning alternative sources substituting slag (H) for obtaining (Ca, Na, K)-poly(sialate-siloxo) networks as binders for sustainable building constructions, e.g., [ 16 , 17 ], and the effect of calcium phosphate compounds on the mechanical and microstructural properties of metakaolin-based geopolymers, e.g., [ 18 ]. Other directions of recent research concerning new binders for building construction are acid-based geopolymers, including calcined laterites [ 19 ].…”

Section: Discussionmentioning

confidence: 99%

The Effect of Gel-Type Contributions in Lime-Sand Bricks, Alkali-Activated Slags and CEMI/CEMIII Pastes: Implications for Next Generation Concretes

Rüscher

Lohaus

Jirasit

et al. 2021

Gels

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Lime-sand bricks of different ages were investigated using IR-spectroscopy, thermogravimetry, and X-ray diffraction/scattering. After subtraction of the dominant quartz contribution (80%), the IR spectra show the absorption peaks of the hydrothermally formed binder phases. The spectra also show the alteration of the binder during ageing under atmospheric conditions by the influence of CO2 forming carbonate and a condensed SiO2-gel (secondary gel). The alteration could also be proven in X-ray pattern, obtaining a separation between crystalline CSH and amorphous contributions in the freshly produced lime-sand brick, too. Here, the formation of CSHamorph could be understood as a precursor state (primary gel) to the crystallization of CSH phases. X-ray patterns of aged bodies of alkali-silicate solution activated slags (AAS), CEM-I/CEM-III pastes, and CEM-I concrete indicate that in all cases a similar amorphous CSH-type phase (CSHamorph) was formed, which is responsible for the hardening properties as the glue. The main X-ray peak of CSHamorph obtained using CuKα-radiation with a usual diffractometer is observed between 24° and 35° 2 Theta with maximum at about 29° 2 Theta, whereas it appears much more broadly distributed between 15° and 35° 2 Theta with maximum between 26° and 28° 2 Theta for a geopolymer body prepared using the reaction of alkali-silicate solution and metakaolin (AAMK). This is due to the network formed by siloxo and sialate units in the case of AAMK, given that any crystallization can be ruled out. The origin of increasing mechanical strength during the ageing of AAS mortars must be due to further crosslinking of the preformed siloxo chains. Thermal treatment up to 800 °C leads to a complete loss of any mechanical strength of the CEM pastes due to the destruction of crystalline CSH-phases, whereas geopolymer bodies maintain their strength. Implications for next generation concrete include that cement clinker could be completely replaced by using a using alkali silcate solution technology for gel formation.

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“…The chemical compositions of the kaolin and rice husk ash are presented in Table 3 . Rice husk ash has already been used and is described by Melele et al [ 41 ], Mabah et al [ 42 ] and Tchakouté et al [ 40 ]. NaOH pellet was provided by the laboratory-grade granules (96 wt.%, Sigma Aldrich, Milano, Italy).…”

Section: Materials and Experimental Methodsmentioning

confidence: 99%

Effects of Iron Minerals on the Compressive Strengths and Microstructural Properties of Metakaolin-Based Geopolymer Materials

Ngnintedem

Lampe

Tchakouté

et al. 2022

Gels

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The current study aims to investigate the influence of iron minerals on the amorphous phase content, compressive strengths and the microstructural properties of the geopolymer materials. Geopolymer materials were prepared by the substitution of metakaolin by 10 and 20 wt.% of each iron mineral sample. Sodium waterglass from rice husk ash was used as a hardener, and metakaolin was used as an aluminosilicate source. The X-ray patterns show that the iron minerals denoted FR and FB are associated with hematite and magnetite, respectively. FY contains goethite together with a significant content of kaolinite and quartz. It is observed in the XRD patterns and FTIR absorption spectra that the additions of hematite, magnetite and goethite remain largely unreacted in the geopolymer binder. The compressive strengths of the related geopolymer composites show some significant variations indicating certain effects for mechanical stability obtained: 10 wt.% replacement of metakaolin by hematite increased the compressive strength from 51.1 to 55.5 MPa, while 20 wt.% hematite caused a decrease to 44.9 MPa. Furthermore, 10 and 20 wt.% replacement with FB revealed decreased values 47.0 and 40.3 MPa, respectively. It was also found that 10 and 20 wt.% of FY caused lower values of 30.9 and 39.1 MPa, respectively. The micrographs of geopolymer materials present some voids and cracks. The denser matrix is related to a superior gel formation producing a better glue between the crystalline additions. The unsubstituted geopolymer sample provides with about 50% the highest X-ray-amorphous content, whereas the substituted samples range between 35 and 45%, indicating systematically smaller gel contents without any clear trend with the compressive strength variation, however. The strength dependencies reveal more complex interaction between the gel and crystalline additions.

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Influence of the molar ratios CaO/SiO2 contained in the sustainable microcomposites on the mechanical and microstructural properties of (Ca, Na)-poly(sialate-siloxo) networks

Cited by 12 publications

References 26 publications

Eco‐friendly preparation and structural characterization of calcium silicates derived from eggshell and silica gel

Eco‐friendly preparation and structural characterization of calcium silicates derived from eggshell and silica gel

The Effect of Gel-Type Contributions in Lime-Sand Bricks, Alkali-Activated Slags and CEMI/CEMIII Pastes: Implications for Next Generation Concretes

Effects of Iron Minerals on the Compressive Strengths and Microstructural Properties of Metakaolin-Based Geopolymer Materials

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