Dehydration kinetics of calcium aluminate cement hydrate under non-isothermal conditions

Abstract The studies focused on the kinetics of early hydration in the high-calcium aluminate cement (CAC 70)—by-pass cement kiln dusts (BPCKD)—mixtures. For this purpose, the mixtures of cement with this additive or with some potential constituents of dusts were produced. The microcalorimeter was applied to follow the kinetics of hydration. The investigations with the aim of finding the relationship between the components of initial mixtures and the modification of hydration process were carried out. The rheological properties were characterized, and the chemical shrinkage characteristics were produced. The phase assemblage characterization and microscopic observations were done as well. In case of the high-calcium aluminate-based binders, the modification of setting process was observed; the rheological properties and chemical shrinkage were affected too. The acceleration of heat evolution—the shortening of so-called induction period in the presence of BPCKD additive—was observed. The results were compared to those obtained for the CAC with ordinary Portland cement additive. The results of calorimetric measurements are discussed in terms of the chemical and phase assemblage of this additive as compared to the Portland cement clinker precursors and potassium chloride—the solid and liquid components of the dust.

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Leaching kinetics of Cr(VI) phases in the matrices of calcium aluminate cement-bonded refractory castables: Role of micro-silica

Journal of the European Ceramic Society ◽

10.1016/j.jeurceramsoc.2020.07.055 ◽

2020 ◽

Vol 40 (15) ◽

pp. 6123-6131 ◽

Cited By ~ 1

Author(s):

Shengqiang Song ◽

Wenke Zhang ◽

Mithun Nath ◽

Pin-Wen Guan ◽

Zhengliang Xue ◽

...

Keyword(s):

Calcium Aluminate ◽

Calcium Aluminate Cement ◽

Leaching Kinetics ◽

Refractory Castables ◽

Micro Silica ◽

Kinetics Of ◽

Aluminate Cement

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Role of Cement Type on Carbonation Attack

Journal of Materials Research ◽

10.1557/jmr.2002.0271 ◽

2002 ◽

Vol 17 (7) ◽

pp. 1834-1842 ◽

Cited By ~ 29

Author(s):

S. Goñi ◽

M. T. Gaztañaga ◽

A. Guerrero

Keyword(s):

Calcium Aluminate ◽

Calcium Aluminate Cement ◽

Alkali Content ◽

X Ray Diffraction ◽

Before And After ◽

Natural Carbonation ◽

Kinetics Of ◽

Aluminate Cement ◽

Hydrated Calcium

The carbonation of two hydrated ordinary portland cements of alkali content 1.03% or 0.43% Na2O equivalent and hydrated calcium aluminate cement (0.1% Na2O equivalent) was studied in a semi-dynamic atmosphere of 100% CO2, and 65% relative humidity at 20 ± 1 °C, for a period of 100 days. The changes of the microstructure before and during the carbonation were characterized by x-ray diffraction, mercury intrusion porosimetry, and scanning electron microscopy. The kinetics of the process was evaluated from the total CaCO3 content by means of thermogravimetric analysis. The changes of the mechanical flexural strength were also studied. The pore solution was collected and analyzed before and after different periods of time. The results were compared with those obtained under natural carbonation conditions. The results showed that the alkali content of cement does not influence the kinetics of the process when the carbonation is accelerated. In the case of natural carbonation, an induction period is produced in the ordinary portland cement of low alkali content and calcium aluminate cement. The carbonation rate of calcium aluminate cement is the slowest for accelerated and natural carbonation.

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Synthesis and hydration kinetics of calcium aluminate cement with micro MgAl2O4 spinels

Materials Chemistry and Physics ◽

10.1016/j.matchemphys.2015.01.060 ◽

2015 ◽

Vol 154 ◽

pp. 158-163 ◽

Cited By ~ 16

Author(s):

Boquan Zhu ◽

Yanan Song ◽

Xiangcheng Li ◽

Pingan Chen ◽

Zheng Ma

Keyword(s):

Calcium Aluminate ◽

Calcium Aluminate Cement ◽

Hydration Kinetics ◽

Kinetics Of ◽

Aluminate Cement

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Physicochemical, Mineralogical, and Mechanical Properties of Calcium Aluminate Cement Concrete Exposed to Elevated Temperatures

Materials ◽

10.3390/ma14143855 ◽

2021 ◽

Vol 14 (14) ◽

pp. 3855

Author(s):

Amirmohamad Abolhasani ◽

Bijan Samali ◽

Fatemeh Aslani

Keyword(s):

Temperature Rise ◽

Calcium Aluminate ◽

Elevated Temperatures ◽

Ultrasonic Pulse Velocity ◽

Pulse Velocity ◽

Calcium Aluminate Cement ◽

Cement Concrete ◽

Sem Images ◽

Strength Deterioration ◽

Aluminate Cement

One commonly used cement type for thermal applications is CAC containing 38–40% alumina, although the postheated behavior of this cement subjected to elevated temperature has not been studied yet. Here, through extensive experimentation, the postheated mineralogical and physicochemical features of calcium aluminate cement concrete (CACC) were examined via DTA/TGA, X-ray diffraction (XRD), and scanning electron microscopy (SEM) imaging and the variation in the concrete physical features and the compressive strength deterioration with temperature rise were examined through ultrasonic pulse velocity (UPV) values. In addition, other mechanical features that were addressed were the residual tensile strength and elastic modulus. According to the XRD test results, with the temperature rise, the dehydration of the C3AH6 structure occurred, which, in turn, led to the crystallization of the monocalcium dialuminate (CA2) and alumina (Al2O3) structures. The SEM images indicated specific variations in morphology that corresponded to concrete deterioration due to heat.

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