Effects of the type of calorimeter and the use of plasticizers and hydrophobizers on the measured hydration heat development of FGD gypsum

Tydlitát, Vratislav; Tesárek, Pavel; Černý, Robert

doi:10.1007/s10973-007-8709-0

Cited by 20 publications

(8 citation statements)

References 9 publications

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“…The heats of hydration for neat α-hemihydrate and βhemihydrate are reportedly 112 and 100 kJ•kg −1 , respectively. 11 The measured values listed in Table 4 were lower. The heat of hydration, for the Base1 composition, which comprised a combination of CaSO 4 •0.5H 2 O and Al, was measured as 83 ± 4 kJ•kg −1 .…”

Section: ■ Results and Discussionmentioning

confidence: 88%

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Burn Rate of Calcium Sulfate Dihydrate–Aluminum Thermites

Govender

Focke

Tichapondwa

et al. 2018

ACS Appl. Mater. Interfaces

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The energetics of cast calcium sulfate dihydrate-aluminum thermites were investigated. The casts were prepared from water slurries with a solids content below 65 wt %. The base case thermite comprised 60 wt % calcium sulfate dihydrate as the oxidizer with 40 wt % aluminum as fuel. The heat of hydration of the base case was 83 ± 4 kJ·kg (dihydrate basis) and the initial setting time was about 100 min. The compressive strength reached 2.9 ± 0.2 MPa after 3 days of drying in ambient air. The open air burn rate was 12.0 ± 1.6 mm· s and a maximum surface temperature of 1370 ± 64 °C was recorded with a pyrometer. Bomb calorimetry indicated an energy output of 8.0 ± 1.1 MJ·kg, slightly lower than predicted by the Ekvi thermodynamic simulation. Substitution of 10 wt % of the oxidant with copper sulfate pentahydrate significantly decreased the initial setting time of the casts to less than 30 min but a secondary aluminum oxidation reaction commenced after 2 h. The density of the castings was varied by either adding hollow sodium borosilicate microspheres or by adding excess water during the casting process. The addition of the hollow glass microspheres caused a decrease in the burning rate. Dehydration of the casts by thermal treatments at either 155 or 200 °C led to significant increases in the burning rate.

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Section: ■ Results and Discussionmentioning

confidence: 88%

“…The kinetics of the calcium sulfate hydration reactions were investigated using isothermal heat flow calorimetry , at a temperature of 25 °C. The heat flow rate was measured as a function of time and the heat of hydration was determined with a TA Instruments TAM air flow calorimeter.…”

Section: Methodsmentioning

confidence: 99%

Burn Rate of Calcium Sulfate Dihydrate–Aluminum Thermites

Govender

Focke

Tichapondwa

et al. 2018

ACS Appl. Mater. Interfaces

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“…The isothermal heat flow calorimeter KC 01 [7] was applied for the measurement of hydration heat development in the analyzed alkali activated aluminosilicates. The device is based on the differential measurement of heat flow.…”

Section: Experimental Methodsmentioning

confidence: 99%

Monitoring the course of early-age reactions in alkali activated aluminosilicates

2019

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In this paper the reaction heat development of alkali activated aluminosilicates is studied by an isothermal heat flow calorimeter. The highest reaction activity is observed during two hours after mixing. The hydration heat power at early time is influenced mainly by the composition of tested mixtures involving ceramic dust as precursor and different amounts of sodium hydroxide and water glass as activators and by temperature.

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“…The surface distribution of sorbed Pb was examined by Scanning Electron Microscope (SEM) Phenom XL (Phenom World, Eindhoven, the Netherland) with EDS (Energy-Dispersive X-ray spectroscopy) detector. The initial part of hydration process in cement pastes was monitored by isothermal calorimetry (homemade heat flow calorimeter KC01) [38]; two replicates were done. The compressive strength of pastes (after 3, 7, 14 and 28 days of curing) was determined by help of MTS Criterion 43 device with controlled speed of deformation (0.2 mm/s).…”

Section: Methodsmentioning

confidence: 99%

Hydration of Ordinary Portland Cement in Presence of Lead Sorbed on Ceramic Sorbent

et al. 2018

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Lead, a highly toxic element, is frequently present in various solid wastes as well as in industrial effluents. Sorption with a low cost sorbent is a simple way of Pb removal from liquid streams, but stabilization of spent sorbent has to be ensured in order to prevent Pb leaching out and possible environmental contamination. In previous research, ceramic sorbent, generated as waste product in brick industry, was tested as sorbent and proved high sorption capacity for lead. Lead was sorbed partially as hydrocerussite and partially as adsorbed surface layer. The Pb leaching from sorbent was very high and thus further immobilization of sorbent was necessary. Lead, as well as other heavy metals, is known as retarder of the hydration process of Ordinary Portland Cement (OPC), used for the immobilization. In this paper, influence of sorbed Pb and PbO, as reference compound, on cement hydration was studied by calorimetry, thermogravimetry and Magic Angle Spinning Nuclear Magnetic Resonance Spectroscopy (MAS NMR). The sorbed lead was found to be less detrimental to hydration retardation due to the lower solubility of precipitated hydrocerussite in basic environment compared to PbO, which forms plumbate anion.

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Effects of the type of calorimeter and the use of plasticizers and hydrophobizers on the measured hydration heat development of FGD gypsum

Cited by 20 publications

References 9 publications

Burn Rate of Calcium Sulfate Dihydrate–Aluminum Thermites

Burn Rate of Calcium Sulfate Dihydrate–Aluminum Thermites

Monitoring the course of early-age reactions in alkali activated aluminosilicates

Hydration of Ordinary Portland Cement in Presence of Lead Sorbed on Ceramic Sorbent

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