Effect of particle size distribution on the hydration and compressive strength development of α-calcium sulfate hemihydrate paste

Ye, Qingqing; Guan, Baohong; Lou, Wenbin; Li, Yang; Kong, Bao

doi:10.1016/j.powtec.2010.11.001

Cited by 32 publications

(16 citation statements)

References 25 publications

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“…The α-form is an especially valuable building material due to its enhanced mechanical properties after rehydration. The strength of the obtained plaster and the amount of water needed for setting depends on the particle size distribution [2,3]. For example, the modulus of rupture of commercial α-hemihydrate was reported to be approximately 2 MN/m 2 higher than that of the more commonly used β-hemihydrate.…”

Section: Introductionmentioning

confidence: 99%

The crystal growth kinetics of alpha calcium sulfate hemihydrate in concentrated CaCl2–HCl solutions

Feldmann

Demopoulos²

2012

Journal of Crystal Growth

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The crystal growth kinetics of calcium sulfate α-hemihydrate (α-HH) in nearly constant supersaturated HCl-CaCl 2 solutions were investigated. Two types of solutions were used, the first had a low HCl (1.4 mol/L) and high CaCl 2 (2.8 mol/L) concentration and the second had a high HCl (5.6 mol/L) and low CaCl 2 (0.7 mol/L) concentration. These conditions were chosen to represent the first and last stage of a newly developed stage-wise HCl regeneration process. The seeded growth experiments were carried out in a stirred, temperature controlled semi-batch reactor in which supersaturation was kept constant by simultaneous addition of CaCl 2 and Na 2 SO 4 solutions. The influence of the following parameters on α-HH crystal growth was studied: temperature (70-95°C), specific power input of stirring (0.02-1.29 W/kg) and equimolar inflow rate of CaCl 2 and Na 2 SO 4 (0-0.6 mol/h). The crystal growth rate was derived from particle size distribution measurements made with the laser light diffraction technique. It was found that the surface area normalized crystal growth rate increased linearly with the molar inflow rate up to 0.3 mol/h, at higher inflow rates no further increase of the growth rate was observed. Temperature and specific power input, within the investigated ranges, did not show a marked effect on the growth rate, attributable to a diffusion/adsorption controlled growth process. An interesting finding of the present research is the establishment of a positive relationship between the narrowing of the width of the particle size distribution with increasing crystal growth rate. The results show that the resulting particle size distribution is positively related to the reagent inflow rate, a finding that can be applied to the industrial design and scale-up of the α-HH crystallization/HCl regeneration process.

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Section: Introductionmentioning

confidence: 99%

The crystal growth kinetics of alpha calcium sulfate hemihydrate in concentrated CaCl2–HCl solutions

Feldmann

Demopoulos²

2012

Journal of Crystal Growth

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“…Entretanto, discute-se na literatura (CARNEIRO, 1999) a não representatividade do valor do módulo de finura do agregado, podendo aplicar a mesma ideia na avaliação da granulometria do gesso. Ye et al (2011) mostraram que, para um gesso α, diferentes curvas granulométricas podem gerar os mesmos módulos de finura, e que é possível entender a influência da distribuição do tamanho das partículas nas propriedades do gesso a partir do conjunto distribuição, finura e largura de distribuição.…”

Section: Quadro 1 -Codificação E Origem Das Amostras De Gessounclassified

“…Além desses fatores, a relação a/g, a temperatura da água de amassamento, a matéria-prima, a energia de mistura, as impurezas, o tamanho das partículas e a origem mineralógica têm relação com a qualidade do material (ANTUNES;JOHN, 2000;CAMARINI et al, 2016;CAMARINI;PIMENTEL;SÁ, 2011;CAUFIN;PAPO, 1983;CLIFTON, 1973;KARNI;KARNI, 1995;LEWRY;WILLIAMSON, 1994;SCHMITZ;TAVARES, 2009;YE et al, 2011). O estudo de caracterização e avaliação do gesso para revestimento ocorre nos estados anidro, fresco e endurecido.…”

Section: Introductionunclassified

“…Ensaios de granulometria são de grande importância, pois é uma das formas de classificação do gesso, seja para fins de fundição ou revestimento (ABNT, 2017e). Além disso, essa característica influencia em diversas outras propriedades e características do gesso, como na microestrutura, consistência normal e resistência à compressão (YE et al, 2011). Para Cincotto, Agopyan e Florindo (1988), massa específica e unitária são grandezas que caracterizam a homogeneidade do material.…”

Section: Introductionunclassified

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Caracterização mecânica do gesso para revestimento produzido no Polo Gesseiro do Araripe

2019

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Resumo O gesso é um material de grande uso na construção civil, destacando-se seu emprego como pasta de gesso para revestimento. No Brasil, o Polo Gesseiro do Araripe é o maior produtor. Percebe-se a necessidade de conhecimento das propriedades e características desse material, principalmente, com foco no produto acabado como revestimento interno em paredes. Nesse contexto, o presente trabalho visa realizar um estudo de caracterização de cinco amostras de gesso do Polo do Araripe, e avaliar a capacidade aderente dos revestimentos executados em pasta desses gessos. O estudo de caracterização ocorreu no estado anidro, por meio de ensaios de granulometria, massa unitária, massa específica, teores de água livre e de cristalização; no estado fresco, por meio de ensaios de consistência normal, tempo de pega e calorimetria; e no estado endurecido, por ensaios de dureza e resistência à compressão. Os ensaios de resistência de aderência à tração ocorreram nos revestimentos de pasta de gesso executados em base cerâmica, produzidos com e sem pré-umedecimento da base. Com os resultados, verifica-se que as pastas de gesso apresentam desempenhos satisfatórios e semelhantes, independentemente do porte do fabricante; entretanto, alguns requisitos normativos não são atendidos.

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“…At a fixed load level, the intermittent grading of the particle voids is significantly less than the continuous grading. This is the superiority of the intermittent grading [35]. Therefore, the intermittent grading is used to study the effect of Al grading on the mechanical properties of ECSPs in this work.…”

Section: Effect Of Al Gradingmentioning

confidence: 99%

Effects of Aluminum and Temperature on the Tensile Mechanical Properties of Lithium‐Perchlorate/Polyvinyl Alcohol‐Based Electrically Controlled Solid Propellants

Xia

et al. 2019

Propellants Explo Pyrotec

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To study the mechanical properties of lithium‐perchlorate/polyvinyl alcohol‐based aluminized electrically controlled solid propellant (LP/PVA‐Al‐ECSP), the effects of Al particle size, grading, and content on the mechanical properties of the propellant at various temperatures were investigated. The uniaxial tensile experiments were conducted over the temperature range from −40 °C to +50 °C using universal testing machine with a crosshead speed of 100 mm min−1. A scanning electron microscope (SEM) was employed to observe the fracture surface morphologies of the specimens. The results indicate that Al powder and temperature greatly affects the mechanical properties of the composite propellant. From experiments in which the size and the fine‐to‐coarse ratio of Al were changed at constant solid loading, the tensile strength and initial modulus of the propellant are improved with the increase of Al particle size and coarse‐to‐fine ratio at 25 °C. The increase in Al content improves the tensile strength and initial modulus of the propellant, whereas reduces the elongation. The results of experiments in which the temperature changed indicate that the tensile strength and initial modulus of the propellant are improved at low temperatures, whereas the mechanical properties of the propellants deteriorate at high temperatures. The elongation of the propellants is greatly reduced at low temperatures. The stress−strain curve of ECSP shows three regions at low temperatures and five regions at room temperature and high temperatures. The LP/PVA‐Al‐ECSP has poor tensile strength and initial modulus, whereas its elongation is extremely high at room temperature. The propellant with 5 μm Al to 65 μm Al ratio of 3/7 exhibits the best comprehensive mechanical properties.

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Effect of particle size distribution on the hydration and compressive strength development of α-calcium sulfate hemihydrate paste

Cited by 32 publications

References 25 publications

The crystal growth kinetics of alpha calcium sulfate hemihydrate in concentrated CaCl2–HCl solutions

The crystal growth kinetics of alpha calcium sulfate hemihydrate in concentrated CaCl2–HCl solutions

Caracterização mecânica do gesso para revestimento produzido no Polo Gesseiro do Araripe

Effects of Aluminum and Temperature on the Tensile Mechanical Properties of Lithium‐Perchlorate/Polyvinyl Alcohol‐Based Electrically Controlled Solid Propellants

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