Effects of Na: Al and water: solid ratios on the mechanical properties of fly ash based geopolymer

Yaakob, Sarini Mat; Rabat, Nurul Ekmi; Sufian, Suriati

doi:10.1088/1757-899x/458/1/012011

Cited by 2 publications

(1 citation statement)

References 22 publications

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“…The strength reduction can be attributed to the excess amount of silica content as the SiO 2 /Al 2 O 3 molar ratio was increased from 2.69 to 2.75, which can contribute to the impedance of geopolymerization process. Yaacob et al [114] used a S/L ratio of 0.33 to produce a geopolymer coating with maximum adhesion strength of 3.8 MPa.…”

Section: Factor Affecting Geopolymer Pastementioning

confidence: 99%

The Suitability of Photocatalyst Precursor Materials in Geopolymer Coating Applications: A Review

et al. 2022

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Today, the building and construction sector demands environmentally friendly and sustainable protective coatings using inorganic coating materials for safe, non-hazardous, and great performance. Many researchers have been working on sustainable solutions to protect concrete and metal infrastructures against corrosion and surface deterioration with the intention of introducing green alternatives to conventional coatings. This article presents a review of developments of geopolymer pastes doped with different types of photocatalyst precursors including factors affecting geopolymer properties for enhancing coating with photocatalytic performance. Photodegradation using geopolymer photocatalyst has great potential for resolving harmless substances and removing pollutants when energized with ultraviolet (UV) light. Although geopolymer is a potentially new material with great properties, there has been less research focusing on the development of this coating. This study demonstrated that geopolymer binders are ideal precursor support materials for the synthesis of photocatalytic materials, with a significant potential for optimizing their distinctive properties.

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Section: Factor Affecting Geopolymer Pastementioning

confidence: 99%

The Suitability of Photocatalyst Precursor Materials in Geopolymer Coating Applications: A Review

et al. 2022

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Influence of Silica Modulus on the Activation of Amorphous Wollastonitic Hydraulic Binders with Different Alumina Content: Study of Hydration Reaction and Paste Performance

Antunes,

Santos,

Horta

et al. 2024

Materials

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This study investigates how different sodium silicate SiO2/Na2O MS ratios (0.75, 0.9, and 1.2) affect the hydration behavior of amorphous wollastonitic hydraulic (AWH) binders containing various amounts of Al2O3 content (4, 7, 10, and 12%wt). The effects of and interaction between the MS ratio of the activator and the Al2O3 content of the sample on the hydration reaction and paste performance were investigated. The reaction was followed by calorimetry, and the pastes’ compressive strength performances were tested at different curing times (2, 7, and 28 days). The hydrated pastes were characterized by FTIR, thermogravimetry analysis, and X-ray diffraction. The calorimetric results show that a higher Al2O3 cContent and a higher MS ratio result in a longer induction period. In terms of paste performance, an increase of the Al2O3 coupled with an activation with a 1.2 MS ratio results in a lower compressive strength after 28 days of hydration; the results range from 76 to 52 MPa. A decrease of the MS ratio to 0.9 allowed the obtention of a narrower range of results, from 76 to 69 MPa. Even though a decrease of the MS ratio to 0.75 led to higher hydration kinetics and high compressive strength results at early ages, at 28 days of curing, a decrease in compressive strength was observed. This may be a consequence of the fast kinetic of the mixture, since the rapid growth of hydration products may inhibit the dissolution at later ages and increase the porosity of the paste. Moreover, the high Al intake in the hydration product, facilitated by the high sodium content of the activator, promotes the formation of a higher number of calcium aluminate silicate hydrate structures (C-A-S-H) to the detriment of calcium silicate hydrate structures (C-S-H), decreasing the compressive strength of the samples. The TGA results indicate that the samples hydrated with the MS075 solution resulted in a higher number of hydrated products at early ages, while the samples hydrated with the MS09 and MS1.2 solutions exhibit a steady increase with curing time. Hence, an equilibrium in the hydration kinetic promoted by Si saturation–undersaturation appears to be fundamental in this system, which is influenced by both the MS ratio and the Al(OH)4− content in solution. The results of this study suggest that for this type of binder, optimal performance can be achieved by decreasing the MS ratio to 0.9. This composition allows for a controlled kinetic and overall higher compressive strength results in pastes produced with this AWH precursor.

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Effects of Na: Al and water: solid ratios on the mechanical properties of fly ash based geopolymer

Cited by 2 publications

References 22 publications

The Suitability of Photocatalyst Precursor Materials in Geopolymer Coating Applications: A Review

The Suitability of Photocatalyst Precursor Materials in Geopolymer Coating Applications: A Review

Influence of Silica Modulus on the Activation of Amorphous Wollastonitic Hydraulic Binders with Different Alumina Content: Study of Hydration Reaction and Paste Performance

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