Effect of micro-sized alumina powder on the hydration products of calcium aluminate cement at 40 °C

Shang, Xue‐Jun; Ye, Guotian; Zhang, Yaqian; Li, Huanhuan; Hou, Di

doi:10.1016/j.ceramint.2016.06.005

Cited by 28 publications

(23 citation statements)

References 16 publications

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“…Furthermore, the SEM examination also showed, especially in the mortars with V-TiO 2 , some areas of stacked hexagonal thin layers that have been ascribed to C 2 AH 8 and C 2 ASH 8 , stratinglite (thickness around 0.1 microns), according to the EDS elemental mapping analysis (Figure 11j,k, outlined areas with white ovals; Figure 11l shows a detailed examination of these piles of layered crystals). These compounds have been reported to be formed in CAC under hydration conditions similar to those of the curing condition 2 of the current work [38,39,40,41,42,43,44]. These phases grew at the expense of CAH 10 and should be expected to convert into C 3 AH 6 at later hydration stages.…”

Section: Resultssupporting

confidence: 68%

The Effect of TiO2 Doped Photocatalytic Nano-Additives on the Hydration and Microstructure of Portland and High Alumina Cements

et al. 2017

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Mortars with two different binders (Portland cement (PC) and high alumina cement (HAC)) were modified upon the bulk incorporation of nano-structured photocatalytic additives (bare TiO2, and TiO2 doped with either iron (Fe-TiO2) or vanadium (V-TiO2)). Plastic and hardened state properties of these mortars were assessed in order to study the influence of these nano-additives. Water demand was increased, slightly by bare TiO2 and Fe-TiO2, and strongly by V-TiO2, in agreement with the reduction of the particle size and the tendency to agglomerate. Isothermal calorimetry showed that hydration of the cementitious matrices was accelerated due to additional nucleation sites offered by the nano-additives. TiO2 and doped TiO2 did not show pozzolanic reactivity in the binding systems. Changes in the pore size distribution, mainly the filler effect of the nano-additives, accounted for the increase in compressive strengths measured for HAC mortars. A complex microstructure was seen in calcium aluminate cement mortars, strongly dependent on the curing conditions. Fe-TiO2 was found to be homogeneously distributed whereas the tendency of V-TiO2 to agglomerate was evidenced by elemental distribution maps. Water absorption capacity was not affected by the nano-additive incorporation in HAC mortars, which is a favourable feature for the application of these mortars.

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Section: Resultssupporting

confidence: 68%

The Effect of TiO2 Doped Photocatalytic Nano-Additives on the Hydration and Microstructure of Portland and High Alumina Cements

et al. 2017

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“…The CAC hydration and CAC hydrate conversion have attracted attention in CAC-bonded castables because these reactions may generate porous channels for released water from the decomposition of the hydrates. 1,8,12,13 As a result, the conversion reactions have an impact on the explosion resistance of CAC-bonded castables. 1 Several hypotheses about the transformation mechanisms of CAC hydrates have been proposed.…”

Section: Introductionmentioning

confidence: 99%

Conversion of calcium aluminate cement hydrates at 60°C with and without water

Zhang

et al. 2018

J Am Ceram Soc

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There have been different hypotheses about the transformation mechanisms of calcium aluminate cement hydrates and this work aims to clarify the long‐running debate about the conversion approaches. In this work, CAH10 and C2AH8 were produced from the pastes of calcium aluminate cement (CAC) cured for 24 hours at 10 and 20°C separately. And the cured pastes were continually cured at 60°C for 3 days with water and without water, respectively. The hydration of the pastes was halted by freeze‐drying, and the phases and microstructure of hydrates were investigated by XRD and SEM, respectively. The results indicate that CAH10 and C2AH8 converted into C3AH6 and AH3 in water presence at 60°C, but did not transform into C3AH6 and AH3 without water. It is confirmed that the conversion of CAH10 and C2AH8 to C3AH6 and AH3 happens through preceding solution of CAH10 and C2AH8 and subsequent precipitation of C3AH6 and AH3.

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“…7b) confirmed the presence of C 3 AH 6 , AH 3 and C 4 A CH 11 and lack of CA 2 . Results of gas evolution curves were not changed significantly (decomposition temperatures: of C 3 AH 6 : 303°C, of AH 3 : 283°C, of C 4 A CH 11 : 150°C) [23][24][25][26][27][28]. SEM observations confirmed the presence of cubic C 3 AH 6 with grain size about 2 lm (Fig.…”

Section: Hydration Of Calcium Aluminate Cement 'Gorkal 70'mentioning

confidence: 89%

“…On the base of gas evolution curves (DSC-TG-EGA(MS)) ( Fig. 10), the main products of hydration were C 3 AH 6 (decomposition temperature: 307°C), AH 3 (decomposition temperature: 283°C) and C 4 A CH 11 (decomposition temperature: 152°C) [23][24][25][26][27][28]. SEM observations confirmed the presence of cubic C 3 AH 6 with a grain size of 1.5-3 lm, hexagonal platelets of metastable hydrates and residue of AH 3 (Fig.…”

Section: Hydration Of Calcium Aluminate Cement 'Gorkal 70'mentioning

confidence: 99%

“…Fine nodules of C 3 AH 6 were obtained from C 2 AH 8 ; the granular-shaped crystals from C 2 AH 8 (in the presence of alumina powder) and 10-100 nm layered nano-particles [4,8,[15][16][17][18][19][20][21][22][23]. Moreover, some authors reported that the presence of gypsum, deflocculants on the basis of polycarbonate ethers and the carbonation process was a favorable factor to give C 3 AH 6 [24][25][26][27][28].…”

Section: Introductionmentioning

confidence: 99%

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Structure, microstructure and thermal stability characterizations of C3AH6 synthesized from different precursors through hydration

Litwinek

Madej

2019

J Therm Anal Calorim

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In this paper, the influence of precursors (CA, C 7 A 3 Z, C 12 A 7 , C 6 SrA 3 Z, C 7 A 2 FZ and commercial calcium aluminate cement 'Gorkal 70') on the structure, microstructure and thermal stability characterizations of C 3 AH 6 through hydration was investigated. The materials were characterized by X-ray diffraction, differential thermal analysis-thermogravimetric analysis-evolved gas analysis and scanning electron microscopy combined with energy-dispersive spectroscopy 24 h and 72 h after starting the hydration process. Results of investigation confirmed the influence of precursor on shape and grain size of C 3 AH 6 . The CaO/Al 2 O 3 mass ratio of precursors before the hydration process affects the size of C 3 AH 6 crystals: the higher the CaO/Al 2 O 3 value, the larger the size of the crystals of C 3 AH 6 . Moreover, the presence of Sr and Fe affects the formation of stable C 3 AH 6 crystals.

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Effect of micro-sized alumina powder on the hydration products of calcium aluminate cement at 40 °C

Cited by 28 publications

References 16 publications

The Effect of TiO2 Doped Photocatalytic Nano-Additives on the Hydration and Microstructure of Portland and High Alumina Cements

The Effect of TiO2 Doped Photocatalytic Nano-Additives on the Hydration and Microstructure of Portland and High Alumina Cements

Conversion of calcium aluminate cement hydrates at 60°C with and without water

Structure, microstructure and thermal stability characterizations of C3AH6 synthesized from different precursors through hydration

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