The change of the peak temperature of the specific heat capacity of gypsum boards mainly affects the simulation accuracy of the dehydration stage of the gypsum board. 14, 15 Therefore, to quantify the impact on peak temperature and determine its value, this section uses the simplified curve of the test results of the ninth working condition ...
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Influence of the Gypsum Dehydration Temperature and Alkali Additives on the Properties of Anhydrite Cement ... pH = 10.20–10.30, when W/S ─ 10. The curve of X-ray diffraction analysis of the ...
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The DSC curve for the dehydration of calcium sulphate dihydrate shows a double peak which was not present in the DSC curve for the dehydration of natural gypsum. The mean weight loss for calcium sulphate dihydrate was 19.2 f 0.89% (which corresponds to the loss of 1.79 water molecules from the reactant) but is somewhat less than the 21% ...
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This article investigates the thermal performance of gypsum boards in the dehydration temperature region, where pronounced chemical reactivity is anticipated. Gypsum board samples were gradually heated up to 3008C, using a low heating rate. ... In particular, the ASTM E119 temperature curve was designed to represent cellulosic fuels that are ...
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We present 35 experiments on gypsum dehydration with independently controlled confining pressure, pore fluid pressure and temperature. Results show that a pore fluid pressure decrease at constant confining pressure has a strong effect on the average rate of the reaction. ... All volume expulsion curves show a sigmoidal form as expected from ...
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Gypsum plaster is an inorganic binder that is prepared in a two-step process. The first step is dehydration: heated to 100–200 °C, gypsum (CaSO 4 ·2H 2 O) releases water as vapor [1, 2] and, depending on temperature and water vapor partial pressure (p H2O) [3, 4] forms either hemihydrate (CaSO 4 •½H 2 O) or γ-anhydrite (CaSO 4), the main components of the …
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DSC curves as a function of sample temperature and heat ramp curves for the chemically bound water dehydration reaction of a commercial gypsum board (a and c) and …
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This article investigates the thermal performance of gypsum boards in the dehydration temperature region, where pronounced chemical reactivity is anticipated. Gypsum board samples were gradually heated up to 300°C, using a low heating rate.
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Download scientific diagram | European fire testing standard time/temperature curves (ISO 834 = curve #1). from publication: Enhanced Gypsum Panels for Fire Protection | The fireproofing materials ...
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Download scientific diagram | Pressure^temperature graph showing the gypsum-out curve from Zen (1965), the metastable bassanite-in curve of McConnell et al . (1987), 30 8 C km À 1 and 15 8 C km ...
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For the measuring temperature of 80 °C the data show two different steps of dehydration more pronouncedly than the data obtained at 84 °C, with a linear time dependence of the fraction of conversion over approximately 20 h and up to ~13% of gypsum dehydrated to bassanite, followed by a sigmoidal fraction of conversion curve (which reaches ...
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With the addition of gypsum (CaSO4.2H2O), the initial decomposition temperature decreased slightly relative to that of EPS/HFR0 due to dehydration of the gypsum to form thermally stable calcium ...
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This article investigates the thermal performance of gypsum boards in the dehydration temperature region, where pronounced chemical reactivity is anticipated. ... (2012) 141–147 Fig. 1. DSC curves as a function of sample temperature and heat ramp curves for the chemically bound water dehydration reaction of a commercial gypsum board (a and c ...
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The dehydration started at the temperature under 50 °C and lasted up to 500 °C. The structure and composition of the gypsum at elevated temperatures were studied by means of scanning electron microscopy, X-ray diffraction (XRD) and the ... The DSC curve of gypsum powder showed an endothermic peak at the temperature 180 °C, which corresponded ...
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curves of gypsum boards. First, the effect of test parameters was quantified by 10 groups of specific heat capacity tests of gypsum boards through the uniform ... ten levels, the peak temperature of dehydration and dehydration energy was used as the test indexes. The test arrangement was con-ducted using the uniform table U* 10(108) ...
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Fig. 1 illustrates the DSC curves for the dehydration of gypsum board chemically bound water (Fig. 1 a) and the evaporation of the deionized water (Fig. 1 b) as a function of sample temperature, for different heating rates, at autogenous water vapour partial pressure conditions, as well as a typical heat ramp (temperature over time) showing the ...
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According to the thermal curves, the gypsum dehydration comports two steps described by the following equations: CaSO 4 •2H 2 O( s )→CaSO 4 •1/2H 2 O( s )+3/2H 2 O( g ) (I)
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This article investigates the thermal performance of gypsum boards in the dehydration temperature region, where pronounced chemical reactivity is anticipated. Gypsum board samples were gradually heated up to 3008C, using a low heating rate. ... The temperature evolution at the center of the sample (curve C1) is similar to the temperature rise ...
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The temperature at which the gypsum binder (calcium sulfate hemihydrate) is industrially produced, between 80 and 180 °C, is often mentioned in the literature [14,15,16,17].However, dehydration from gypsum to basanite (CaSO 4 ·0.5H 2 O) starts at a much lower temperature. The dehydration temperature depends on the measurement method, the …
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From the weight loss curves obtained by DVS it is evident that the humidity has an important influence on the dehydration process. The time to weight equilibrium shortens drastically with …
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Jacques et al. [26] found that the dehydration temperature of waste gypsum is lower than that of pure gypsum, implying that the presence of impurity ion might lower the dehydration temperature for ...
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tion engineering for the dehydration of a lump sample of gypsum was also developed by Sugiyama et al.1>3>10) andSugimoto et al.9). However, it has not yet been elucidated how dehydration temperature, equilibrium dehydration pressure, and dehydration rate are inter-related to each other. In this paper, the drying and the thermal dehydration
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Considering the B1-B2 interface, time–temperature curves of specimen BR-SGP-S4 as an example (Fig. 10), at the beginning of the fire test, due to the large amount of heat absorbed through heating-induced dehydration and water evaporation of the fire-side gypsum boards, the time–temperature curve of the B1-layer, gypsum board cold surface ...
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The dehydration products of gypsum under different temperature and water vapor pressure were investigated by thermodynamic theory. Additionally, the rehydration mechanism of soluble anhydrite was also studied by Monte Carlo (MC) simulations. The thermodynamic calculation results reveal that the dehy …
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Herein, an in situ high–temperature synchrotron X–ray diffraction study of gypsum is performed in the temper-ature range of 30–200 °C to investigate the continuous structural change from …
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NOV.1985 Thermal Analysis of Gypsum 1. Introduction Gypsum has long been used as a building material and is used for that purpose in the following items. ... The DSC curve reached maximum around 180°C. The thermal ratio of the two peaks was 3 to 1 (75% to 25%), which corresponds well with the ratio of
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Gypsum plaster is an inorganic binder that is prepared in a two-step process. The first step is dehydration: heated to 100–200 °C, gypsum (CaSO 4 ·2H 2 O) releases water as vapor [1,2] and, depending on temperature and water vapor partial pressure (p H2O) [3,4] forms either hemihydrate (CaSO 4 •½H 2 O) or γ-anhydrite (CaSO 4), the main components of the …
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1. Ultrasonic results indicate gypsum hydration reaction consists of two stages: the dissolution of hemihydrate in the first stage and the nucleation and precipitation of dihydrate in the second stage. 2. Gypsum hydration is strongly influenced by water amount. Spread flow test is suitable to determine the water demand for gypsum hydration.
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The dependence of the solubility of gypsum on temperature is nonlinear, reaching a maximum at 43°C. ... = Curves for gypsum and. ... that gypsum dehydration occurs widely.
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Typical DTA curves of natural gypsum samples from different locations are shown in Fig. 2 (a–d). ... °C correspond to dehydration of gypsum; in the temperature range (400–900) °C decomposition and dissociation of some impurity minerals occurs, for example calcite, which is contained in samples ##5, 7, 12.
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