Contributions to the study of porosity in fly ash-based geopolymers. Relationship between degree of reaction, porosity and compressive strength

Luna-Galiano, Y.; Fernández‐Pereira, Constantino; Izquierdo, María

doi:10.3989/mc.2016.10215

Cited by 50 publications

(29 citation statements)

References 45 publications

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“…Additionally, higher percentages of RHA provide a higher concentration of soluble silica, which hinders the geopolymerization process , resulting in more unreacted or partially reacted material particles (as observed from Figure ) and thus limiting the pore refinement/filler effect. Moreover, a low reactivity of RHA in comparison with FA may be another possible cause of low geopolymerization reaction rate . These test results are in good agreement with the strength development of brick samples, as the more the void volume within the bricks, the higher the water absorption rate and the poorer the brick strength is.…”

Section: Resultssupporting

confidence: 73%

Effect of residual rice husk ash on mechanical‐microstructural properties and thermal conductivity of sodium‐hydroxide‐activated bricks

Huynh

Hwang

Lin

et al. 2017

Env Prog and Sustain Energy

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This research compares the mechanical‐microstructural properties and thermal conductivity of the solid, green construction bricks that contain different percentages of sodium‐hydroxide‐activated residual rice husk ash and class‐F fly ash. The brick specimens were prepared following the guidelines of Vietnamese national standard in term of mixing, forming, and curing. Various percentages of rice husk ash (0%, 10%, 20%, 30%, 40%, and 50%) were added to a standard brick mixture in order to evaluate the influence of rice husk ash content on the strength development, void volume, water absorption capacity, bulk density, and thermal conductivity of the hardened bricks. Moreover, scanning electron microscopy was used to characterize surface morphologies of the brick samples. Further, the suitability of using a binder of rice husk ash and fly ash to produce alkali‐activated construction bricks was investigated. The bricks that were produced demonstrated generally good engineering performance and conformed to the relevant Vietnamese codes. Of particular note, the addition of rice husk ash influenced the properties of the bricks significantly, with brick strength peaking at a rice husk ash content of 10% and decreasing progressively at higher percentages. The findings from the present study support the efficacy of using a binder that contains rice husk ash and fly ash to produce green alkali‐activated construction bricks. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 1647–1656, 2018

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Section: Resultssupporting

confidence: 73%

Effect of residual rice husk ash on mechanical‐microstructural properties and thermal conductivity of sodium‐hydroxide‐activated bricks

Huynh

Hwang

Lin

et al. 2017

Env Prog and Sustain Energy

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“…Figures 4e and 4f show mechanical performance in mortars AAFA. Strength was much lower in these mortars than in the other two at all the ages studied (44). In the 28 day specimens, 100% replacement of siliceous aggregate by R or H aggregates induces a steep decline in compressive strength (72% and 56% for R and H respectively).…”

Section: Mechanical Performancementioning

confidence: 76%

Viability of the use of construction and demolition waste aggregates in alkali-activated mortars

2018

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This study explores the technological feasibility of using construction and demolition waste (C&DW) as recycled aggregate in alkali activated mortars, ascertaining the mechanical and microstructural behavior. Shrinkage behavior of alkali activated slag mortars (AAS) and fire resistance of alkali activated fly ash (AAFA) incorporating recycled aggregates have been also tested Normalized siliceous sand and two types of recycled concrete aggregates were used in the mixes at different proportions. The findings showed that water demand was higher in mortars prepared with recycled aggregate. Partial replacement (20% - 80/20) of conventional aggregate with the recycled material was also observed to yield mortars with high mechanical strength, although total porosity also rose. Total replaclement, gave worse mechanical performance however. Fire resistance and shrinkage studies conducted indicated that alkaline cement mortars prepared with 80/20 recycled aggregated exhibit acceptable performance.

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“…Furthermore, the XRD peak between 20° and 40° is higher for the water-glass activating solution than that for the hydroxide activating solution. Although both activating solutions have a pH of 14, the hydroxide activating solution yields a lower reactivity than the silicate activating solution during the geopolymerization reaction [ 22 ].…”

Section: Resultsmentioning

confidence: 99%

Microstructure, Compressive Strength and Sound Insulation Property of Fly Ash-Based Geopolymeric Foams with Silica Fume as Foaming Agent

Liu

Chu

2020

Materials

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Geopolymer as an alternative to cement has gained increasing attention. The aim of this article is to study the influence of the silica fume content and activator type on the porous fly ash-based geopolymer with silica fume as foaming agent. Geopolymeric foams were fabricated using low-calcium fly ash, silica fume, and sodium-based alkaline activator as initial materials. The designed silica fume contents were 0, 15, 30, and 45 wt % and two kinds of activators of water glass and sodium hydroxide were used for comparison. Phase composition, microstructure, mechanical properties and sound insulation properties of as-prepared bulks were systematically investigated. It was found that, with increasing silica fume content, the density and compressive strength decreased simultaneously, whereas the porosity and sound insulation performance were effectively enhanced. At the silica fume content of 45% with sodium hydroxide as activator, the porosity was increased 3.02 times, and, at the silica fume content of 45% with water glass as activator, the mean sound insulation value of 43.74 dB was obtained.

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Contributions to the study of porosity in fly ash-based geopolymers. Relationship between degree of reaction, porosity and compressive strength

Cited by 50 publications

References 45 publications

Effect of residual rice husk ash on mechanical‐microstructural properties and thermal conductivity of sodium‐hydroxide‐activated bricks

Effect of residual rice husk ash on mechanical‐microstructural properties and thermal conductivity of sodium‐hydroxide‐activated bricks

Viability of the use of construction and demolition waste aggregates in alkali-activated mortars

Microstructure, Compressive Strength and Sound Insulation Property of Fly Ash-Based Geopolymeric Foams with Silica Fume as Foaming Agent

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