Fibers, Geopolymers, Nano and Alkali-Activated Materials for Deep Soil Mix Binders

Wong, John Kok Hee; Kok, Sien Ti; Wong, Soon Yee

doi:10.28991/cej-2020-03091511

Cited by 13 publications

(3 citation statements)

References 52 publications

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“…This partial replacement will affect the mechanism and rate of formation hydration products. [2] Alkali-activated slag produces hydration products based on C-(A)-S-H gel and, in the case of activated fly ash, hydration products based on N-A-S-H gel are formed [2,[8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Influence of Fly Ash Denitrification on Properties of Hybrid Alkali-Activated Composites

2022

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This article deals with the possibility of partial replacement of blast furnace slag (GGBFS) with fly ash after denitrification (FAD) in alkali-activated materials. Physical-mechanical and durability properties were tested, hydration reaction was monitored, and infrared spectroscopy was performed. Results were compared between mixtures prepared with fly ash without denitrification (FA), and also with a mixture based only on GGBFS. The basic result is that hybrid alkali-systems with FAD show similar trends to FA. The significant effect of fly ash is manifested in terms of its resistance to freeze-thaw processes. Reactions in a calorimeter show a slower development of reactions with increasing replacement of GGBFS due to the lower reactivity of the fly ash. Through testing the leaching resistance, a decrease in flexural strength was found. This may be due to the descaling of the main hydration product, C–(A)–S–H gel. After 28 days of maturation, compressive strengths of all monitored mixtures ranged from 96 to 102 MPa. The flexural strengths ranged from 6.8 to 8.0 MPa. After 28 days of maturation, the higher strengths reached mixtures without replacing GGBFS. In terms of resistance to freeze-thaw processes, the largest decrease (almost 20%) of flexural strength was achieved by a mixture with 30% of GGBFS replacement by FA. No fundamental differences were found for the mixtures in the FTIR analysis.

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Section: Introductionmentioning

confidence: 99%

Influence of Fly Ash Denitrification on Properties of Hybrid Alkali-Activated Composites

2022

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“…This partial replacement will affect the mechanism and rate of formation hydration products. [2] Alkali-activated slag produces hydration products based on C-(A)-S-H gel and in the case of activated fly ash, hydration products based on N-A-S-H gel are formed [2,[8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Influence of Fly Ash Denitrification on Properties of Hybrid Alkali Activated Composites

Procházka¹,

Boháčová²,

Vojvodíková³

2022

Preprint

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This article deals with the possibility of partial replacement of blast furnace slag with fly ash after denitrification by the Selective Non-Catalytic Reduction (SNCR) method in alkali-activated materials. In the experiment, the basic physical-mechanical properties and durability properties were tested, the hydration reaction was monitored in a calorimeter and infrared spectroscopy was performed. Results were compared between mixtures prepared with fly ash without denitrification and also with reference mixture based only on alkali-activated blast furnace slag. The basic result is the finding, that hybrid alkali-systems with fly ash after denitrification show similar trends as hybrid alkali-systems with fly ash without denitrification. The significant effect of fly ash is manifested especially in terms of resistance to freeze-thaw. The reactions in the calorimeter show a slower development of reactions with increasing replacement of slag by fly ash. In the case of testing resistance to leaching in demineralised water, a decrease of flexural strength was found, which corresponds to the conclusions of strength testing, that long-term deposition of bodies in water causes deterioration of mechanical properties.

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“…This addition affects the mechanism and rate of gel formation. In the case of slag alkali activation by the silicate solution, the gel of type C-A-S-H dominates, and in the case of fly ash alkali activation by the silicate solution, N-A-S-H is formed [2][3][4][5][6][7]. The combination of blast furnace slag and fly ash produces these products simultaneously if the amount of fly ash does not exceed 75%.…”

mentioning

confidence: 99%

Effect of Admixtures on Durability Characteristics of Fly Ash Alkali-activated Material

Procházka

Boháčová

2020

Emerg Sci J

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This paper deals with the possibility of partial replacement of blast furnace slag with fly ash and fly ash after denitrification by SNCR method in alkali-activated materials based on granulated blast furnace slag. The aim of this paper is to verify the effect of fly ash on properties of alkali-activated materials based on blast furnace granulated slag. Frost resistance and resistance to aggressive environments, represented by demineralized water were tested. The reference mixture was based on blast furnace granulated slag activated by sodium water glass with silicate modulus of 2. Mixtures with an ash content of 10, 20, and 30% were then compared with the reference mixture. The influence of the denitrification process on fly ash and its use in mixed alkali activated materials was also compared. As a part of the experiment, alkali-activated pastes were also prepared. Infrared spectroscopy with Furier transformation was subsequently determined on these pastes. The reference mixture achieved the highest compressive strength in the experiment and the strength decreased with increasing amount of fly ash. In terms of flexural strength, the highest values were reached for mixtures with 10% slag replacement by fly ash. In the case of frost resistance, the significant increase of flexural strength, which was 50% for the reference mixture, is particularly interesting. For compressive strength, the frost resistance coefficient ranged from 0.95 to 1.00. In the case of resistance to aggressive environments, no differences were observed in the compressive strength, on the other hand, flexural strength decrease of up to 20% was detected for 10 and 20 percent replacement of slag with fly ash that did not undergo denitrification. Monitored properties did not show any negative effect of the denitrification process on fly ash properties. Infrared spectroscopy identified the main hydration product in the region of 945 cm-1which is a C-(A)-S-H gel and in combined mixtures with fly ash also N-A-S-H gel. Doi: 10.28991/esj-2020-01247 Full Text: PDF

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Fibers, Geopolymers, Nano and Alkali-Activated Materials for Deep Soil Mix Binders

Cited by 13 publications

References 52 publications

Influence of Fly Ash Denitrification on Properties of Hybrid Alkali-Activated Composites

Influence of Fly Ash Denitrification on Properties of Hybrid Alkali-Activated Composites

Influence of Fly Ash Denitrification on Properties of Hybrid Alkali Activated Composites

Effect of Admixtures on Durability Characteristics of Fly Ash Alkali-activated Material

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