Water retention and setting in gypsum/polymers composites Zatrzymanie wody i zestalanie w kompozytach gips/polimer

Kocemba, Aleksandra; Mucha, Maria

doi:10.15199/62.2016.5.22

Cited by 6 publications

(7 citation statements)

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“…The value of σ max depends on the porosity of the material and increases with w/g. Cellulose ethers cause a few percent increase in water retention in the system containing gypsum [8,18]. Therefore, it is proposed that two different types of pores (of different origin) exist in the material.…”

Section: Mechanical Resultsmentioning

confidence: 99%

“…Several explanations can be found in the literature [11][12][13][14][15][16][17][18][19][20][21][22] for the retardation in gypsum (or cement) hydration in the presence of organic compounds such as: nucleation control, disturbance in the crystal growth, decrease in ion mobility [4]. The water-soluble polymers such as cellulose ethers contain numerous hydroxyl groups which are able to form hydrogen bonds with oxygen ions on the surface of anhydrous materials (absorption).…”

Section: Kinetics Of Gypsum Crystallization/hydrationmentioning

confidence: 99%

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Microstructural formation of gypsum by setting in the presence of hydroxypropyl methylcellulose (HPMC)

Mucha

Mróz

Wrona

et al. 2020

J Therm Anal Calorim

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The role of a polymer as a retarder additive is to enhance workability of the gypsum paste by modifying its setting process and to improve its properties. The study focuses on the influence of water-soluble cellulose derivative hydroxypropyl methylcellulose (HPMC) on the setting kinetics as well as on the properties and the microstructure of gypsum. The influence of HPMC (used in mass fractions of up to 1.5%) on the kinetics of crystallization/hydration of hemihydrate calcium sulfate was investigated by heat flow measurements using differential scanning calorimetry (DSC). To describe the experimental results, the Avrami equation was used and its parameters n and K were determined. The hydration/crystallization process was modified by the presence of the polymer. As a result, the K value decreased, but n ≈ 2.5 pointed to the three-dimensional diffusion-controlled mechanism. The morphology studies involved porosity measurements. Mechanical properties of the gypsum plaster composites were examined using the bending strength test and correlated with the sample microstructure.

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Section: Mechanical Resultsmentioning

confidence: 99%

Section: Kinetics Of Gypsum Crystallization/hydrationmentioning

confidence: 99%

Microstructural formation of gypsum by setting in the presence of hydroxypropyl methylcellulose (HPMC)

Mucha

Mróz

Wrona

et al. 2020

J Therm Anal Calorim

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“…Among the many cellulose ethers, HEMC (Sigma Aldrich, Warsaw, Poland) has found a wide application in material engineering, as it is used to modify building materials based on gypsum or cement [ 5 , 14 , 15 , 16 ]. In turn, silica aerogel particles were used; the particles had a fraction size within the range of 0.7–4.0 mm [ 17 , 18 ].…”

Section: Methodsmentioning

confidence: 99%

“…More detailed information concerning the chemical structure, chemical composition and microstructure of the additives used is presented in publications [ 5 , 14 , 15 , 16 ].…”

Section: Methodsmentioning

confidence: 99%

“…The gypsum composites were conditioned for 28 days under the same conditions as the geopolymer samples. The view of the geopolymer and gypsum samples after the conditioning time is shown in Figure 1a More detailed information concerning the chemical structure, chemical composition and microstructure of the additives used is presented in publications [5,[14][15][16].…”

Section: Methodsmentioning

confidence: 99%

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Comparison of the Thermal Properties of Geopolymer and Modified Gypsum

et al. 2021

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The paper presents the results of research concerning the influence of micromaterials on the heat conductivity coefficient λ, specifically heat Cp and thermal diffusivity a of modified gypsum and geopolymer. Microspheres, hydroxyethyl methylcellulose (HEMC) polymer, and aerogel were used as the gypsum’s modifying materials. The study also investigated an alkali potassium-activated methakaolin-based geopolymer with the addition of aluminium dust. During the measurements of thermal parameters, the nonstationary method was chosen, and an Isomet device—which recorded the required physical quantities—was used. When compared to the reference sample, a decrease in the thermal conductivity and diffusivity of the hardened gypsum— and a simultaneous increase in specific heat—was observed with the addition of micromaterials. The geopolymer sample was characterized by the lowest value of thermal conductivity, equal to 0.1141 W/(m·K). It was over 62% lower than the reference sample containing only gypsum. The experimental values of the thermal conductivity of the gypsum samples with the addition of HEMC, aerogel and microspheres were, respectively, over 23%, 6%, and 8% lower than those of the unmodified gypsum samples. The lowest values of thermal conductivity were observed in the case of the gypsum samples modified with polymer; this resulted from the fact that the polymer caused the greatest change in the structure of the gypsum’s composite, which were expressed by the lowest density and highest porosity.

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