Autogenous shrinkage of slag-fly ash blends activated with hybrid sodium silicate and sodium sulfate at different curing temperatures

Uppalapati, Siva; Çizer, Özlem

doi:10.1016/j.conbuildmat.2020.121276

Cited by 30 publications

(8 citation statements)

References 63 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The effect of higher amounts of GGBS in alkali-activated GGBS/fly ash is to decrease the setting time as shown in Figure 6(a) and (b), which is consistent with the literature [27]. The fast setting time associated with the presence of GGBS may be addressed in various ways, such as the addition of up to 2% microsilica [29]. Borax may also be used to increase setting time [42].…”

Section: Effect Of Naoh Molarity On Initial Setting (Is) and Final Setting (Fs) Timessupporting

confidence: 83%

“…Calcium is abundant in GGBS precursor in the form of CaO. The fast dissolution of Al and Si, in addition to abundance of calcium, modifies the network and forms reaction products at faster rate [29].…”

Section: Effect Of Naoh Molarity On Initial Setting (Is) and Final Setting (Fs) Timesmentioning

confidence: 99%

“…In addition to C-A-S-H, the presence of fly ash promotes formation of sodium aluminosilicate (N-A-S-H) which is more porous and less compact than C-A-S-H [28]. Uppalapati et al [29] reported that in the early hours after mixing GGBS-fly ashy binder combination, only C-A-S-H is present due to the fast hydration of GGBS with little or no N-A-S-H. This is because dissolution of fly ash takes longer time than hydration of GGBS.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Fresh Properties and Sulfuric Acid Resistance of Sustainable Mortar Using Alkali-Activated GGBS/Fly Ash Binder

Mohamed

Khattab

2022

Polymers

View full text Add to dashboard Cite

In this study, sorptivity, setting time, resistance to sulfuric acid, and compressive strength of mortars that use alkali-activated GGBS and fly ash as binders, were evaluated experimentally. The activation of binders, was achieved at room temperature of 222 0C using combinations of sodium silicates (Na2SiO3) and sodium hydroxide (NaOH) solutions in ratios of 1.5, 2.0, and 2.5. The parameters considered in terms of their effects on fresh and hardened properties include: NaOH molarity, activator ratio Na2SiO3/NaOH, mortar sample age, and relative amount of GGBS/fly ash in binder combination. Sorptivity, change in mass, and compressive strength were determined for mortar samples that were submerged in 10% sulfuric acid solution for 7 days, 28 days, and 90 days. The binder for mortar samples tested at each of the specified ages consisted of 100% GGBS (G100), 75%GGBS+25% fly ash (G75F25), or 50% GGBS + 50% fly ash (G50F50). The binder was activated using Na2SiO3 solution, combined with 10M, 12M, 14M, or 16M NaOH solution. It was found that sorptivity decreases with increase in curing age, for all activator ratios, concentrations, and relative amounts of GGBS/fly ash. Binder consisting of 75%GGBS + 25% fly ash with NaOH concentration of 12M had the lowest sorptivity. Eexposure of alkali-activated GGBS/fly ash mortar samples to sulfate attack did not cause loss in mass nor visible signs of damage/deterioration. All binder combinations experienced increase in compressive strength after curing in 10%sufluric acid solution, with the optimum G75F25 mix achieving a 28-day strength of 80.53 MPa when NaOH molarity is 10M, which increased to 91.06 MPa after 90 days. Variation in concentration of NaOH didn’t cause significant change in the magnitudes of 28-day or 90 day compressive strengths of G50F50. However, despite slow dissolution of fly ash and immersion in 10% sulfuric acid solution, G50F50 developed 28-day compressive strength of 56.23 MPa and 90-day compressive of 86.73 MPa, which qualifies G50F50 as high strength mortar for practical purpose.

show abstract

Section: Effect Of Naoh Molarity On Initial Setting (Is) and Final Setting (Fs) Timessupporting

confidence: 83%

Section: Effect Of Naoh Molarity On Initial Setting (Is) and Final Setting (Fs) Timesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Fresh Properties and Sulfuric Acid Resistance of Sustainable Mortar Using Alkali-Activated GGBS/Fly Ash Binder

Mohamed

Khattab

2022

Polymers

View full text Add to dashboard Cite

show abstract

“…This is mainly due to the large variety in the precursors and activators that are used in these systems 5–7 . The complexity is further increased with the variation in the physical and chemical properties of the precursors, blending of different precursors 8,9 and using different compositions of activators 10,11 . Although this makes AAM systems challenging to analyze, the variability present in component and composition choices increases the flexibility for customizing the final product in line with specific project requirements.…”

Section: Introductionmentioning

confidence: 99%

Effect of nanoparticles on the hydration of NaOH‐activated GGBFS

Joseph,

Unluer

2023

J Am Ceram Soc.

View full text Add to dashboard Cite

The effect of nanoparticles and nucleation seeds on the hydration kinetics of alkali‐activated materials is not well understood. Implications of nano‐TiO2 (nTiO2) and C–S–H nucleation seeds (XSeed) on the early‐age hydration and later‐age properties of sodium hydroxide‐activated ground granulated blast furnace slag were investigated. The effect of NaOH concentration (0.5, 1, 2, and 4 M) in the activator solution was reported. Results indicated the acceleration of early hydration kinetics with mixes of XSeed and nTiO2 when the concentration of the activator solution was 0.5/1 M. No considerable effects were noted with XSeed addition for 2/4 M, whereas there was an acceleration with the addition of nTiO2. These differences were attributed to the lack of dispersion of XSeed at higher activator concentrations. Hydrate phase assemblage did not change with the addition of nanoparticles by 28 days of hydration. Increase in strength, along with pore refinement, was observed with the incorporation of nanoparticles.

show abstract

“…Uppalapati et al 38 demonstrated that increasing Na 2 O content from 1.75 to 2.75% increases the 1-, 3-, 7-, and 28-day compressive strength of GGBS + fly ash (GGBS/fly ash = 80%/20% by volume) mortars, activated using a mixture of sodium silicate and sodium sulfate solutions. Similarly, increasing the curing temperature from 20 to 40 °C also consistently increases the compressive strength at each of the curing days.…”

Section: Introductionmentioning

confidence: 99%

Effect of relative GGBS/fly contents and alkaline solution concentration on compressive strength development of geopolymer mortars subjected to sulfuric acid

Mohamed

Khattab

Hawat

2022

Sci Rep

View full text Add to dashboard Cite

The effect of submerging geopolymer mortar samples in highly acidic solution for 7-, 28-, and 90-days on stability of mass and the development of compressive strength development was assessed experimentally. The mortar binder consisted of GGBS or blends of GGBS and fly ash activated using combinations of NaOH and Na2SiO3 solutions, and samples were cured in room temperature. It was found that maintaining mortar samples continuously under sulfuric acid doesn’t cause reduction compressive strength or mass from one age to the other, up to 90 days. While decalcification, delaumination, and formation of calcium salts due to sulfate attack may have affected mass and strength, submerging samples under water supported formation of geopolymerization products C-A-S-H and N-A-S-H, and consequently increased the mass and compressive strength of cubic mortar samples with fly ash + GGBS blended binder. The resistance of mortar to sulfuric acid remained consistent when mortars were prepared using GGBS:fly ash ratio of 3:1, equal amounts of GGBS and fly ash, and GGBS as sole binder. When geopolymer mortar samples made with each of the three binders was left exposed to air after casting, compressive strength increased from 7- to 28-days after casting, but at 90-days, all mortar samples experienced decrease in compressive strength relative to the 28-day values. The relatively high content of GGBS (≥ 50%) and absence of curing water in relatively dry conditions caused shrinkage cracking and decrease in compressive strength.

show abstract

Autogenous shrinkage of slag-fly ash blends activated with hybrid sodium silicate and sodium sulfate at different curing temperatures

Abstract: The autogenous shrinkage increased with increasing the concentration of sodium sulfate solutions. Increasing curing temperature decreased the autogenous shrinkage of AASF systems. The S ions provided by the activating solutions have limited influence on the reaction process.

Cited by 30 publications

References 63 publications

Fresh Properties and Sulfuric Acid Resistance of Sustainable Mortar Using Alkali-Activated GGBS/Fly Ash Binder

Fresh Properties and Sulfuric Acid Resistance of Sustainable Mortar Using Alkali-Activated GGBS/Fly Ash Binder

Effect of nanoparticles on the hydration of NaOH‐activated GGBFS

Effect of relative GGBS/fly contents and alkaline solution concentration on compressive strength development of geopolymer mortars subjected to sulfuric acid

Contact Info

Product

Resources

About