Hydration reactions and microstructural characteristics of hemihydrate with citric and malic acid

Magallanes-Rivera, R.X.; Escalante-Garcı́a, J.I.; Gorokhovsky, Alexander

doi:10.1016/j.conbuildmat.2008.07.022

Cited by 68 publications

(21 citation statements)

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“…by forming complexes or chelating agents with the active ions in the nucleating solutions (equation 1; where x = 2 for maleic/tartaric acids or 3 for citric acid) or by sorbing to active crystal sites and inhibiting mineral growth (e.g. Crabtree et al, 1999;Badens et al, 1999;Ersen et al, 2006;Magallanes-Rivera et al, 2009).…”

Section: Discussionmentioning

confidence: 99%

Carboxylic acids: effective inhibitors for calcium sulfate precipitation?

2014

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Results are reported here of an investigation into the effects of three carboxylic acid additives (tartaric, maleic and citric acids) on the precipitation of calcium sulfate phases. Precipitation reactions were followed at pH 7 in the pure CaSO 4 system and in experiments with 0À20 ppm carboxylic acids added using in situ UV-VIS spectrophotometry (turbidity). The solid products were characterized in terms of their mineralogical composition, using X-ray diffraction, during and at the end of each reaction, and in terms of their morphological features, by scanning electron microscopy. All additives increased the time needed for turbidity to develop (induction time, start of precipitation) and the comparison between additive and additive-free experiments showed that, at equivalent concentrations, citric acid performed far better than the other two carboxylic acids. In all cases bassanite precipitated first and with time it transformed to gypsum. The addition of citrate stabilized bassanite and changed the final gypsum habit from typical needle-like crystals in the pure CaSO 4 system to plates in the citrate-additive experiments.

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Section: Discussionmentioning

confidence: 99%

Carboxylic acids: effective inhibitors for calcium sulfate precipitation?

2014

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“…Badens et al [17] showed that the retarding action of citric and malic acids was caused by the adsorption of the acids onto the gypsum crystals, which acted as nucleation sites. Magallanes-Rivera et al [18] reasoned that the addition of the acids divided the hydration process into two stages. In the first stage, adsorption of the acids onto the hemihydrate retarded its dissolution.…”

Section: Introductionmentioning

confidence: 99%

Thermal conductivity and strength of foamed gypsum formulated using aluminum sulfate and sodium bicarbonate as gas-producing additives

Umponpanarat

Wansom

2015

Mater Struct

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The present work aimed to explore the potential of using Al 2 (SO 4 ) 3 and NaHCO 3 as gasproducing additives for the formation of foamed gypsum. Three systems of additives, namely Al 2 (SO 4 ) 3 ? CaCO 3 , Al 2 (SO 4 ) 3 ? citric acid, and NaHCO 3 , were investigated for their foam-forming ability in order to lower the thermal conductivity while preserving the compressive strength of the foamed gypsum. Emphasis was given to the setting time such that it would lie within 20-25 min, for the formulation to be practically useful. The results showed that, within the desired setting time, NaHCO 3 provided the lowest thermal conductivity (*0.22 W/mK) and the highest efficiency (i.e., the highest rate of the thermal conductivity reduction for each percent of additives) among the three systems studied. It was also the system that best preserved the compressive strength for every unit reduction in the thermal conductivity. However, the corresponding compressive strength of 0.72 MPa was still very low, about three times lower than that of the other systems. The Al 2 (SO 4 ) 3 ? CaCO 3 system yielded a lower thermal conductivity (*0.24 W/mK) than the Al 2 (SO 4 ) 3 ? citric system (*0.31 W/mK), although their corresponding compressive strengths (*2.4 MPa) were quite similar. Therefore, given the desired setting time, the Al 2 (SO 4 ) 3 ? CaCO 3 system produced the best combination of thermal conductivity and compressive strength.

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“…Calorimetric studies have been a useful tool to understand the hydration reactions by following the heat liberation rate (HLR) of the reacting PC (15), the technique can also be applied to other cementitious materials (16,17). It is generally accepted that the curves of hydration of PC show 5 periods I -preinduction, II -induction, III -acceleration, IV -deceleration and V -diffusion (6,17).…”

Section: Early Hydrationmentioning

confidence: 99%

“…Isothermal conduction calorimetry (ICC), based on the Forrester design (15,16), was carried out to follow the early hydration of samples of about 15 g at 20 °C. The SC pastes were mixed inside the cells of the calorimeter, so the collected data included from the hydration time =0.…”

Section: Characterizationmentioning

confidence: 99%

Early and late hydration of supersulphated cements of blast furnace slag with fluorgypsum

Bazaldúa-Medellín¹,

Fuentes²,

Gorokhovsky³

et al. 2015

Mater. construcc.

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ABSTRACT:The hydration, strength development and composition of hydration products of supersulphated cements were characterized from the first 48 hours up to 360 days. Two compositions of 80% Blast furnace slag, 10-15% Fluorgypsum and 10-5% Portland cement were cured in dry and wet conditions. The main hydration products were ettringite and C-S-H since the first hours and up to 360 days as evidenced by X-ray diffraction, thermal analysis and electron microscopy. The strength was favored by higher fluorgypsum contents and lower Portland cement contents. These cements generated heats of hydration of 40-57 KJ/Kg after 28 hours, which are lower than portland cement. RESUMEN: Hidratación temprana y tardía de cementos supersulfatados de escoria de alto horno con fluoryeso.Se realizó la caracterización de la hidratación, desarrollo de resistencia y la composición de los productos de hidratación de los cementos supersulfatados durante las primeras 48 horas y hasta 360 días. Se estudiaron dos composiciones de 80% de Escoria de alto horno, 10-15% de Fluoryeso y 10-5% de Cemento portland, se curaron en condiciones secas y húmedas. Los principales productos de hidratación fueron etringita y C-S-H desde las primeras horas y hasta 360 días, como se evidenció por difracción de rayos X, análisis térmico y microscopía electrónica de barrido. La resistencia se favoreció con mayor contenido de fluoryeso y bajos contenidos de cemento portland. Estos cementos generaron calores de hidratación de 40-57 KJ/Kg después de 28 horas, los cuales resultan más bajos que los generados por el cemento portland.

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Hydration reactions and microstructural characteristics of hemihydrate with citric and malic acid

Cited by 68 publications

References 4 publications

Carboxylic acids: effective inhibitors for calcium sulfate precipitation?

Carboxylic acids: effective inhibitors for calcium sulfate precipitation?

Thermal conductivity and strength of foamed gypsum formulated using aluminum sulfate and sodium bicarbonate as gas-producing additives

Early and late hydration of supersulphated cements of blast furnace slag with fluorgypsum

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