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Das, Swapan Kumar; Kumar, Surendra; Poddar, Palash

doi:10.1023/a:1018529030346

Cited by 8 publications

(4 citation statements)

References 3 publications

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“…After 3 days of hydration as appeared in Fig. 8 b, the crystals are densely packed together with the distribution of the hydrated alumina (AH 3 ) that gave the particles a darker grey color 40 . Moreover, the size of the crystals has decreased with a significant decrease in the pores as well.…”

Section: Resultsmentioning

confidence: 90%

“…= 1390 °C) 34 – 37 formed in “CA60” specimens. Regarding the effect of sintering temperature on the densification behavior of sintered samples “CA40-70”, there was an increase in bulk density and a decrease in apparent porosity with the enhancement of sintering temperature from 1250 to 1450 °C due to the phenomenon of sintering densification and the gradual sedimentation of the formed phases in the voids, which reduces the apparent porosity and enhances the bulk density 12 , 29 , 38 – 40 . Among the tested samples, the “CA60” specimen sintered at 1450 °C revealed the lowest apparent porosity (0.9 vol%) and the highest bulk density (2.7 g/cm 3 ), revealing a semi-molten, fully-dense structure.…”

Section: Resultsmentioning

confidence: 99%

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Maximize the use of municipal waste generated by the hydrogen peroxide industry in the production of high-quality refractory CAC

Amer

El-Maddah

Abuelela

et al. 2022

Sci Rep

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High-grade calcium aluminate cement (CAC) has been successfully synthesized from municipal alumina waste and limestone under mild reaction conditions. Mineralogical composition and microstructure of the sintered mixes were investigated using X-ray diffraction and FESEM; valuable cementing phases such as CA, CA2, and C12A7 were observed in addition to the C3A phase that was detected in the mixes with high CaCO3 content. Mix CA60 containing 60 wt% alumina waste has achieved the best sinterability (less than 1 vol% porosity) and the highest densification (~ 2.65 g/cm3 bulk density) at 1450 °C. Densification, cold-crushing strength (CCS), and microstructure of the hydrated cement samples (From Mix CA60) were investigated. The cast cement specimens revealed better density and CCS characteristics (63.1 and 74 MPa at 7 and 28 days, respectively) in comparison with the commercial cement. Conventional castables (5 × 5 × 5 cm3) were prepared from mixtures composed of 15 wt% cement and 85 wt% aggregates (40% Al2O3), where CA60 and commercial cement were used to compare the effect of the manufactured CA60 cement with the commercial one. The castables prepared with CA60 cement have shown a higher strength at 110 °C with 4.5 MPa when compared to the commercial CAC at the same temperature (1.8 MPa). Accordingly, this study contributes not only to preserving the environment from the accumulation of industrial wastes but also to valorizing and adding value to these wastes.

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Section: Resultsmentioning

confidence: 90%

Section: Resultsmentioning

confidence: 99%

Maximize the use of municipal waste generated by the hydrogen peroxide industry in the production of high-quality refractory CAC

Amer

El-Maddah

Abuelela

et al. 2022

Sci Rep

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“…10-11 ppm. (Figure 5a-point 1) with a cubic/isometric crystal form [30,31]. The EDS spectrum presenting intensity vs. energy of the detected X-ray clearly identifies the peaks of Sr, Ca, Al and O (Figure 5b).…”

Section: Preparation and Treatment Of Cement Pastementioning

confidence: 94%

“…Figure 5 shows the typical microstructure of this cement paste fragment after 24 h hydration at 50°C. The presence of Sr in Sr1.25Ca5.75ZrAl6O18 clinker affects formation of Sr-rich (Sr,C)3AH6 (Figure 5a-point 1) with a cubic/isometric crystal form [30,31]. The EDS spectrum presenting intensity vs. energy of the detected X-ray clearly identifies the peaks of Sr, Ca, Al and O (Figure 5b).…”

Section: Microstructural Studies On the Hydrated Sr125ca575zral6o18mentioning

confidence: 96%

Strontium Retention of Calcium Zirconium Aluminate Cement Paste Studied by NMR, XRD and SEM-EDS

Madej

2020

Materials

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This work concerns the hydration mechanism of calcium zirconium aluminate as a ternary compound appearing in the CaO-Al2O3-ZrO2 diagram besides the calcium aluminates commonly used as the main constitutes of calcium aluminate cements (CACs). Moreover, a state-of-the-art approach towards significant changes in hydraulic properties was implemented for the first time in this work, where the effect of structural modification on the hydration behavior of calcium zirconium aluminate was proved by XRD, 27Al MAS NMR and SEM-EDS. The substitution of Sr2+ for Ca2+ in the Ca7ZrAl6O18 lattice decreases the reactivity of Sr-substituted Ca7ZrAl6O18 in the presence of water. Since the original cement grains remain unhydrated up to 3 h (Ca7ZrAl6O18) or 72 h (Sr1.25Ca5.75ZrAl6O18) of curing period in the hardened cement paste structures, strontium can be considered as an inhibition agent for cement hydration. The complete conversion from anhydrous 27AlIV to hydrated 27AlVI species was achieved during the first 24 h (Ca7ZrAl6O18) or 7 d(Sr1.25Ca5.75ZrAl6O18) of hydration. Simultaneously, the chemical shift in the range of octahedral aluminum from ca. 4 ppm to ca. 6 ppm was attributed to the transformation of the hexagonal calcium aluminate hydrates and Sr-rich (Sr,C)3AH6 hydrate into the cubic phase Ca-rich (Sr,C)3AH6 or pure C3AH6 in the hardened Sr-doped cement paste at the age of 7 d. The same 27Al NMR chemical shift was detected at the age of 24 h for the reference hardened undoped Ca7ZrAl6O18 cement paste.

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Understanding the binding and leaching of Cr(VI) in calcium aluminate cement based solidified/stabilized pastes

Zhang

Chen

Zhang

et al. 2020

Construction and Building Materials

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Untitled

Cited by 8 publications

References 3 publications

Maximize the use of municipal waste generated by the hydrogen peroxide industry in the production of high-quality refractory CAC

Maximize the use of municipal waste generated by the hydrogen peroxide industry in the production of high-quality refractory CAC

Strontium Retention of Calcium Zirconium Aluminate Cement Paste Studied by NMR, XRD and SEM-EDS

Understanding the binding and leaching of Cr(VI) in calcium aluminate cement based solidified/stabilized pastes

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