Improvement of acid resistance of Portland cement pastes using rice husk ash and cement kiln dust as additives

Hashem, F. S.; Amin, M. S.; El-Gamal, S. M. A.

doi:10.1007/s10973-012-2458-4

Cited by 47 publications

(17 citation statements)

References 20 publications

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“…The DSC curves indicate two main endothermic peaks located at 90-105°C and 420°C. The first endotherm located at 90-105°C is mainly due to the removal of residual free water as well as dehydration of the sulphoaluminate hydrates and the amorphous part of calcium silicate hydrates (CSH) [46]. The enthalpies of this endotherm are 14.6, 23.82 and 16.2 J/g for specimens made from mixes A0, B0 and D0 respectively; the marked increase in the enthalpy value in case of specimens made of mix B0 is attributed to the formation of additional amount of CSH, as a result of the pozzolanic reaction of Homra with free calcium hydroxide liberated from OPC hydration.…”

Section: Differential Scanning Calorimetrymentioning

confidence: 99%

Fire resistance and mechanical properties of carbon nanotubes – clay bricks wastes (Homra) composites cement

Amin

El-Gamal

Hashem

2015

Construction and Building Materials

115

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Section: Differential Scanning Calorimetrymentioning

confidence: 99%

Fire resistance and mechanical properties of carbon nanotubes – clay bricks wastes (Homra) composites cement

Amin

El-Gamal

Hashem

2015

Construction and Building Materials

115

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“…These traces can be formed as a result of long-term contact with the external environment. A mass change at *430°C (*2 mass% for the ACZ and ACD samples, a trace for the ACB sample) for all of the samples indicates the presence of portlandite (Ca(OH) 2 ) [39,40]. This is one of the main minerals in cement paste.…”

Section: Resultsmentioning

confidence: 97%

“…For all of the samples, this was a water loss from the CSH phase [38,39]. Endothermic peaks at *520°C for the samples indicated the presence of portlandite (Ca(OH) 2 ), which was one of the abundant phases in the hydrated cement pastes [39,40]. The weakest effect connected with the dehydroxylation of portlandite (Ca(OH) 2 ?…”

Section: Resultsmentioning

confidence: 97%

Thermal decomposition of asbestos-containing materials

Kusiorowski

Zaremba

Piotrowski

et al. 2013

J Therm Anal Calorim

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Asbestos is the common name applied to a group of natural, fibrous silicate minerals, which were once one of the most popular raw materials to be used in building materials. Asbestos was mainly used for the production of assortment asbestos-cement products. Today it is generally known that asbestos belongs to the group of hazardous materials and shows carcinogenic activity. In Poland, asbestos-containing materials are stored in special landfills. This is not the final solution to the asbestos problem because the fibrous structure of asbestos is still maintained. Therefore, methods based on recycling must be found which will be able to destroy asbestos' dangerous fibrous structure. One of these methods may be thermal decomposition, where chemically combined water is released from the asbestos materials during heating. This leads to changes in the crystal structure and to the formation of new mineral phases. The aim of the preliminary research presented in this study was to determine the thermal behaviour as well as the structural and phase transformations of asbestos-cement materials during heating to high temperature. In the present study, three different types of asbestos-containing materials from Poland were examined. Differential thermal analysis, thermogravimetry with evolved gas analysis, X-ray diffraction, infrared spectroscopy and scanning electron microscopy were used to study the thermal decomposition of asbestos-cement samples. It was found that there were no significant differences between the type of asbestos-cement samples used-their thermal decomposition takes place in a similar way.

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“…Previous works [16][17][18][19][20][21][22][23][24][25][26][27] indicated various decomposition temperatures of Ca-Al hydrates, obtained by thermal analysis methods. According to both Fleisher [16] and Hill [17], C 4 AH [13][14][15][16][17][18][19] phase decomposes in the temperature range 200-280°C or at a temperature of 250°C, respectively.…”

Section: Introductionmentioning

confidence: 99%

“…George [19] reports an endothermic peak due to dehydration of C 2 AH 8 at 170°C. Various authors [9,[20][21][22][23][24][25][26][27] have reported DTA curves including evidence for the presence stable cubic C 3 AH 6 . All report an endothermic peak due to dehydration somewhere in the range 300-330°C.…”

Section: Introductionmentioning

confidence: 99%

Hydration, carbonation and thermal stability of hydrates in Ca7−xSrxZrAl6O18 cement

Madej

2017

J Therm Anal Calorim

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This paper studies hydration stages and phase transformation mechanism of the Sr 2? -doped calcium zirconium aluminate cement at room temperature. Features of different hydration stages of this cement paste are identified by X-ray diffraction, scanning electron microscopy, differential thermal analysis, thermogravimetric analysis, evolved gas analysis and heat evolution test. It was found that the partial isovalent substitution of Ca 2? for Sr 2? such as Ca 7-x Sr x ZrAl 6 O 18 , with x = 0.3, 0.6, 1.0, reduced the hydraulic reactivity of Ca 7 ZrAl 6 O 18 phase. The course of hydration of mixed oxides of the type 6CaOÁSrOÁ3Al 2 O 3 Á ZrO 2 documented using microcalorimetry was supported by investigations of the solid hydration products. Research showed that the hexagonal hydrates were stable at early and middle curing ages, an indication that including Sr in solid solution could effectively inhibit the conversion from both C 4 AH 13-19 and C 2 AH 8 to C 3 AH 6 and AH 3 . Calcium monocarboaluminate C 4 A CH 11 phases were also found in this system due to the carbonation process of C 4 AH 13 phase. Substitution of Ca 2? ions by Sr 2? ions in hexagonal calcium aluminate hydrates causes structural disorder and then contributes to the broadening of lines in the powder X-ray diffraction patterns of layered structures of metastable hydrates. At later curing ages, the formation of two hydrogarnet phases, one Sr-rich (C,Sr) 3 AH 6 and the other Ca-rich (C,Sr) 3 AH 6 , was proved.

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Improvement of acid resistance of Portland cement pastes using rice husk ash and cement kiln dust as additives

Cited by 47 publications

References 20 publications

Fire resistance and mechanical properties of carbon nanotubes – clay bricks wastes (Homra) composites cement

Fire resistance and mechanical properties of carbon nanotubes – clay bricks wastes (Homra) composites cement

Thermal decomposition of asbestos-containing materials

Hydration, carbonation and thermal stability of hydrates in Ca7−xSrxZrAl6O18 cement

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