Characterization of gypsum using TMDSC

Dantas, Herbert Figueiredo; Mendes, R. A. S.; Pinho, R. D.; Soledade, L. E. B.; Paskocimas, C. A.; Lira, Belarmino Barbosa; Schwartz, Manfred O. E.; Souza, A. G.; Santos, I. M. G.

doi:10.1007/s10973-006-7733-9

Cited by 25 publications

(10 citation statements)

References 10 publications

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“…Its use in construction dates back to the Neolithic age, and it still represents a commodity material in the building industry with an annual worldwide production of about 150 million tons . Consequently, the formation, , processing, and mechanical properties of gypsum and its related compounds, anhydrite (CaSO 4 ) and bassanite (CaSO 4 ·0.5H 2 O), have been studied in great detail. Using infrared spectroscopy, the water dynamics inside gypsum crystals can be studied, indicating that the crystal water in bulk gypsum is constrained to a single conformation .…”

Section: Introductionmentioning

confidence: 99%

Does the Structural Water within Gypsum Remain Crystalline at the Aqueous Interface?

Söngen

Silvestri

Roshni³

et al. 2021

J. Phys. Chem. C

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Solid−liquid interfaces are omnipresent in nature and technology. Processes occurring at the mineral−water interface are pivotal in geochemistry, biology, as well as in many technological areas. In this context, gypsumthe dihydrate of calcium sulfateplays a prominent role due to its widespread distribution in the Earth's crust and its manifold applications in technology. Despite this, many fundamental questions regarding the molecular-scale structure, including the fate of the crystal water molecules at the aqueous interface, remain poorly studied. Here, we present an atomic force microscopy (AFM) and molecular dynamics (MD) investigation to elucidate molecular-level details of the gypsum−water interface. Three-dimensional AFM data shed light into the hydration structure, revealing one water molecule per surface unit cell area in the lowest layer accessible to experiment. Comparing with simulation data suggests that the AFM tip does not penetrate into the surface-bound layer of crystal water. Instead, the first hydration water layer on top of the crystal water is mapped. Our findings indicate that the crystal water at the interface remains tightly bound, even when in contact with bulk water. Thus, the interfacial chemistry is governed by the crystal water rather than the calcium or sulfate ions.

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Section: Introductionmentioning

confidence: 99%

Does the Structural Water within Gypsum Remain Crystalline at the Aqueous Interface?

Söngen

Silvestri

Roshni³

et al. 2021

J. Phys. Chem. C

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“…In materials such as silica, researchers have identified that the phase transformation of the materials due to the increase in the contact stresses is the primary reason for pop-in events in the loading curves [ 23 , 25 ]. However, for porous materials (such as shales, plaster, or other cementitious materials), phase transformations due to temperature changes [ 44 , 45 ] and hence the pop-in events in such materials can be attributed to the possible dislocation networks and cracking during the indentation loading.…”

Section: Resultsmentioning

confidence: 99%

Application of Nanoindentation in the Characterization of a Porous Material with a Clastic Texture

Kasyap

Senetakis

2021

Materials

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In materials science and engineering, a significant amount of research has been carried out using indentation techniques in order to characterize the mechanical properties and microstructure of a broad range of natural and engineered materials. However, there are many unresearched or partly researched areas, such as, for example, the investigation of the shape of the indentation load–displacement curve, the associated mechanism in porous materials with clastic texture, and the influence of the texture on the constitutive behavior of the materials. In the present study, nanoindentation is employed in the analysis of the mechanical behavior of a benchmark material composed of plaster of Paris, which represents a brand of highly porous-clastic materials with a complex structure; such materials may find many applications in medicine, production industry, and energy sectors. The focus of the study is directed at the examination of the influence of the porous structure on the load–displacement response in loading and unloading phases based on nanoindentation experiments, as well as the variation with repeating the indentation in already indented locations. Events such as pop-in in the loading phase and bowing out and elbowing in the unloading phase of a given nanoindentation test are studied. Modulus, hardness, and the elastic stiffness values were additionally examined. The repeated indentation tests provided validations of various mechanisms in the loading and unloading phases of the indentation tests. The results from this study provide some fundamental insights into the interpretation of the nanoindentation behavior and the viscoelastic nature of porous-clastic materials. Some insights on the influence of indentation spacing to depth ratio were also obtained, providing scope for further studies.

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“…With regard to different phases of calcium sulfate, crystal water content is one of the key parameters to assess their phase transformation and crystallization . Hence, TG analysis was performed and the results are shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Effect of CuCl₂ on hydrothermal crystallization of calcium sulfate whiskers prepared from FGD gypsum

Wang

Jin

Yang

et al. 2015

Crystal Research and Technology

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Using purified flue‐gas desulfurization (FGD) gypsum as raw material, effects of CuCl2 on crystal morphology, phase structure, aspect ratio and crystallization of hydrothermal products prepared via hydrothermal crystallization in H2SO4‐H2O solutions were investigated. The results show that dosage of CuCl2 has a significant effect on the morphology, aspect ratio and crystallization of calcium sulfate whiskers (CSWs), but no effect on their phase transformation. At a dosage of 15 g CuCl2/kg FGD gypsum, the produced calcium sulfate whiskers had diameters ranging from 1 to 3 μm with average aspect ratio greater than 200. Transmission electron diffraction patterns and highly magnified surface morphology of CSWs were found different from those of self‐assembly crystals. Compared to self‐assembly crystals, the produced CSWs showed a single crystal structure and their surface was very smooth.

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Characterization of gypsum using TMDSC

Cited by 25 publications

References 10 publications

Does the Structural Water within Gypsum Remain Crystalline at the Aqueous Interface?

Does the Structural Water within Gypsum Remain Crystalline at the Aqueous Interface?

Application of Nanoindentation in the Characterization of a Porous Material with a Clastic Texture

Effect of CuCl₂ on hydrothermal crystallization of calcium sulfate whiskers prepared from FGD gypsum

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Characterization of gypsum using TMDSC

Cited by 25 publications

References 10 publications

Does the Structural Water within Gypsum Remain Crystalline at the Aqueous Interface?

Does the Structural Water within Gypsum Remain Crystalline at the Aqueous Interface?

Application of Nanoindentation in the Characterization of a Porous Material with a Clastic Texture

Effect of CuCl2 on hydrothermal crystallization of calcium sulfate whiskers prepared from FGD gypsum

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Product

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Effect of CuCl₂ on hydrothermal crystallization of calcium sulfate whiskers prepared from FGD gypsum