Structure Of Gypsum Research Articles

Application of ATR-FTIR spectroscopy in tandem with chemometrics for assessing the firing conditions of Hellenistic and Roman ceramic shards excavated from the ancient city of Stratonikeia in South-Western Turkey

The use of attenuated total reflectance (ATR) Fourier transform infrared (FTIR) spectra combined with chemometrics were tested to assess the firing conditions of the shard samples excavated from the ancient city of Stratonikeia. Totally thirty-six principal component analysis (PCA) models were compared according to their ability to classify fifty-five shard samples. The PCA model using normal FTIR spectra ranged between 825 and 400 cm−1 with 25 smoothing points showed the best classification results by dividing the shard samples into five different groups (A, B, C, D, E) based on their different spectral information. To determine the firing conditions and the mineralogical compositions of the shard groups, the second-derivative ATR-FTIR spectra (two polynomial degrees and 11 smoothing points of Savitzky-Golay) between 1700 and 400 cm−1 was successfully used. It was determined that the minerals of pseudo-amorphous structure of meta-smectite, quartz, muscovite, gehlenite, and gypsum were the main phases in the shard samples fired in the oxidizing atmospheric conditions. The obtained findings indicate that the firing temperature is about 800–950 °C and 600–800 °C for the shard groups of A, B, C, and D and E, respectively.

STUDY OF THE IMPACT OF SURFACTANTS ON THE STRUCTURE FORMATION OF HYDRATED GYPSUM BINDER

Relevance. Ukrainian and foreign researches consider gypsum the most effective material due to its peculiar properties. You can hardly find a material like this that would have the same characteristics, sustainability, and ensure adequate standard of living. The production of building materials based on gypsum binders is not associated with hazardous wastes and emissions and does not cause negative environmental impacts. Besides, the manufacture of gypsum binders requires 3…5 times less energy compared to lime and cement. These advantages encourage researchers to proceed with further attempts to obtain a gypsum structure exhibiting the properties of cement binders. One of the trends involving the formation of this kind of structure is studying the impact of additives on the hydration process. The use of plasticizers is of particular interest in this research area. Problem statement. Structure formation process generally depends on the initial content of binding substances and substances interacting during the hydration process. The analysis of technical publications shows that production of composite binders is a priority in the manufacture of mineral binders. A second priority is the use of various additives and factors affecting the hydration process. Most studies using additives involve the structuring of gypsum- and cement-based materials in order to improve physical and mechanical properties. The literature review conducted shows that there is insufficient information on the hydration process mechanism and impact of plasticizers on the structure formation of mineral binders. The purpose of the article. Assessing the effects of surfactants on the mechanism of structure formation and hydration processes in gypsum binders. Conclusion. The studies conducted helped to identify the effects of surfactants on the structure and properties of hydrated gypsum binder; furthermore, the most effective additives were identified, allowing to reduce water-togypsum ratio significantly, improve strength values, and obtain a binder with a higher density structure. If crystals are grown using СаСІ2 + Nа2SO4 + 2Н2O → СаSО4 ∙ 2Н2О + 2NaCl solution, gypsum specimens will have a high-porosity fibrous microstructure. During counterdiffusion growth of gypsum crystals in the presence of surfactants, filling of interlayer voids can be observed in the microphotographs. Crystals begin to grow from one point, which is due to changes in surface tension. The studies have revealed that plasticizers promote the growth of crystals and the surface energy can be modified depending on the type of additive, which can affect the hardened binder structure. The best results have been achieved with Sika and ACE 430 plasticizers. The X-ray diffraction analysis of the produced СаSО4 ∙ 2Н2О crystals has shown that binder hydration process intensity is related to the impact of additives on the shape and size of calcium sulfate crystals and calcium sulfate dihydrate and depends on facial surface energy.

Experimental analysis of moisture transfer and phase change in porous insulation exposed to fire and its effect on heat transfer

Water vapour in porous building materials significantly affects the heat transfer. In addition to the regular humidity, materials, such as gypsum, release water vapour when they are heated, leading to a high resistivity to fire exposure. Although the heat and water vapour transfer through porous building materials at atmospheric conditions is well investigated, no data are available for the effective diffusion coefficient or velocity of the water vapour transfer when the structure is exposed to a thermal load or fire. For this purpose, fire resistance tests were carried out for gypsum/mineral wool constructions to determine the transient heating characteristic and water vapour transfer. It was found that for thin gypsum structures up to 2.5 cm the heating from ambient temperature to 65 ∘C is mainly caused by conduction. Further heating to 100 ∘C is related to the condensation of water vapour instead of thermal heat conduction. Furthermore, a significant decrease of the effective diffusion coefficient of water vapour in the mineral wool from 33.3 mm2/s to 26.7 mm2/s was determined during fire exposure. Based on the measurement the mean velocity of the water vapour transport was determined of being between 1 and 3 mm/s.

The Effect of Gypsum on the Fixation of Selenium in the Iron/Calcium-Selenium Coprecipitation Process.

The coprecipitation of selenium(IV) (Se) with iron(III) (Fe) is a widely practiced method for the removal of Se from mineral processing effluents, but the effect of gypsum as a major secondary mineral on the iron-selenium coprecipitation process is still of concern. In our work we first investigated the effects of pH, Fe/Se molar ratio and the neutralizing agent on the removal efficiency of Se by iron-selenium coprecipitation method. The developed two-step Fe-Se coprecipitation method (Fe/Se molar ratio of 4) was superior to the one-step Fe-Se coprecipitation method at pH 4 using CaO as base in terms of the stability of the generated Fe-Se coprecipitates. Raman experimental results indicated the iron-selenium coprecipitates had the by-product of calcium selenite. We then investigated the effect of incorporation of Se into gypsum on the coprecipitation process at different pHs. The fourier transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), and scanning electron microscopy (SEM) of the calcium-selenium coprecipitates showed that the Se incorporated into the structure of gypsum at pH 8-10. Therefore, this work has important implications for the development of new technologies for efficient Se removal.

Hybrid TiO2-Polyaniline Photocatalysts and their Application in Building Gypsum Plasters.

Hybrid materials of conjugated polymer and titanium(IV) oxide have attracted considerable attention concerning their potential benefits, including (i) efficient exploitation of visible light, (ii) a high adsorption capacity for organic contaminants, (iii) and effective charge carriers separation. The new class of the photocatalysts is promising for the removal of environmental pollutants in both aqueous and gaseous phases. For the first time, in this study, the polyaniline (PANI)–TiO2 hybrid composite was used for the degradation of phenol in water and toluene in the gas phase. Polyaniline–TiO2 was prepared by the in situ polymerization of aniline on the TiO2 surface. The obtained hybrid material was characterized by diffuse reflectance spectroscopy (DR/UV-Vis), X-ray diffraction (XRD), fast-Fourier transformation spectroscopy (FTIR), photoluminescence (PL) spectroscopy, microscopy analysis (SEM/TEM), and thermogravimetric analysis (TGA). An insight into the mechanism was shown based on the photodegradation analysis of charge carrier scavengers. Polyaniline is an efficient TiO2 photosensitizer for photodegradation in visible light (λ > 420 nm). The trapping experiments revealed that mainly h+ and ˙OH were the reactive oxygen species that were responsible for phenol degradation. Furthermore, the PANI–TiO2 hybrid nanocomposite was used in gypsum plaster to study the self-cleaning properties of the obtained building material. The effect of PANI–TiO2 content on the hydrophilic/hydrophobic properties and crystallographic structure of gypsum was studied. The obtained PANI–TiO2-modified gypsum plaster had improved photocatalytic activity in the reaction of toluene degradation under Vis light.

Changes in structure and composition of gypsum paste at elevated temperatures

The structure and composition of the gypsum at elevated temperatures were studied by means of scanning electron microscopy, X-ray diffraction (XRD) and thermogravimetry (TG). The gypsum paste samples were heated to the temperatures from 50 to 1000 °C. The changes in the structure of gypsum were in good accordance with the changes in properties. The crystals of calcium sulphate dihydrate were disrupted at the temperature between 50 and 100 °C, and the strength decreased significantly; after heating to 700 °C, the crystals started to be thicker and packed closer to each other and the strength increased again. After heating to 1000 °C, the strength was the same as the original strength. The results of XRD showed that the changes of calcium sulphate forms (dihydrate to hemihydrate and then to different modifications of anhydrite) were not sudden but occurred gradually, and different forms of calcium sulphate existed in the heated gypsum paste together. It was confirmed that several parallel or subsequent reactions occurred during dehydration. The dehydration started at the temperature under 50 °C and lasted up to 500 °C.

Incorporation of trace metals Cu, Zn, and Cd into gypsum: Implication on their mobility and fate in natural and anthropogenic environments

The coexistence of calcium (Ca2+), sulfate (SO42−) with trace metal cations (M(II)) can possibly lead to M(II)-gypsum coprecipitation and solid solution formation. However, gypsum's role in the fixation of M(II) is still largely unknown. This study investigated the precipitation of Ca2+ and SO42− in the presence of M(II) (i.e., Cu2+, Zn2+, or Cd2+) and the incorporation of the metal cations into the gypsum structure at different environmental conditions. Trace metals in two natural gypsum samples (Yunnan and Neimeng, China) and one hydrometallurgical byproduct gypsum sample from a Cu refinery were also assessed. X-ray diffraction, scanning electron microscopy-energy dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy were employed to characterize the solid samples. The lab-scale results showed that the M(II) content in the coprecipitates increased with pH and the initial M(II) concentration. At lower pH, Zn2+ and Cd2+ were dominantly fixed through isomorphic substitution for Ca2+ in the gypsum structure, while Cu2+ was likely incorporated into the channel structure of the gypsum where the water molecules reside. In contrast, at higher pH, thermodynamic modeling results indicated that M(II)-hydroxides and base metal sulfates (Mx(OH)y(SO4)z) were formed and constituted an appreciable fraction of M(II)-bearing species in the host solids. Our study further showed that trace amounts of Cu, Zn, and Cd were also substitutianly incorporated in the two natural and one hydrometallurgical gypsum samples. The present study may have important implications for understanding the geochemical cycle of trace metals in Ca2+ and SO42− coexisting systems, as well as possible attenuation mechanisms that may occur along their supersaturation and coprecipitation.

Sequestration of Selenite and Selenate in Gypsum (CaSO4·2H2O): Insights from the Single-Crystal Electron Paramagnetic Resonance Spectroscopy and Synchrotron X-ray Absorption Spectroscopy Study.

Gypsum is the most common sulfate mineral on Earth's surface and is the dominant solid byproduct in a wide variety of mining and industrial processes, thus representing a major source for heavy metal(loid) contamination, including selenium. Gypsum crystals grown from the gel diffusion technique in 0.02 M Na2SeO4 solution at pH 7.5 and 0.02 M Na2SeO3 solutions at pH 7.5 and 9.0 contain 828, 5198, and 5955 ppm Se, respectively. Synchrotron Se K-edge X-ray absorption spectroscopic analyses show that selenite and selenate are the dominant species in Se4+- and Se6+-doped gypsum, respectively. The single-crystal EPR spectra of Se4+- and Se6+-doped gypsum after gamma-ray irradiation reveal five selenium-centered oxyradicals: SeO2-(I), SeO2-(II), SeO2-(III), SeO3-, and HSeO42-. The former three radicals provide unequivocal evidence for the substitution of their paramagnetic precursor SeO32- for SO42- in the gypsum structure, while the latter two confirm the replacement of SeO42- for SO42-. These results demonstrate that gypsum has a significant capacity for sequestrating both selenite and selenate in the structure but has a marked preference for the former, thus confirming important controls on the mobility and bioavailability of selenium oxyanions and pointing to optimal applications of gypsum for remediating selenium contamination under neutral to alkaline conditions.

Atık Selülozik Karışımı Kaynaklardan Üretilen Alçı Esaslı Levhalar: 2. Bölüm. Kimyasal ve Teknolojik Özellikler

En yüksek toplam renk farkı (∆E) benzer üretim şartlarında atık kağıt ve eski oluklu muykavvalardan üretilmiş levhalarda (A4: 6.09; B4: 5.79) gözlemlenmiştir. Bu levhalara aynı zamanda en düşük CIE whiteness değerleri göstermiştir (A4: -33.19; B4: -28.44). FTIR tekniği yarımıyla levhaların yüzeylerindeki kimyasal gruplar incelenmiştir. A ve C tipi levhaların diagramları benzerlik göstermekle birlikte B tipi levhaların TGA diyagramları oldukça farklı olduğu anlaşılmıştır. Özellikle başlangış sıcaklık değerlerinde (100-120 0C) B tipi levhaalrın ağırlık kaybı diğer A ve C tipi levhadan daha yüksektir. Bu durum muhtemelern atık oluklu mukavva (B tipi levha) yapısında selülozik liflerden ayrı olarak daha yüksek oranda nişasta, silika, lignin bulunmasından ileri gelmesindir. Deneme levhalarının yüzeyine uygulanan alevin, tüm levhalar için kritik eşik değer olan 150 mm seviyesine gelmediği gözlemlenmiştir. Alev uzaklaştırıldıktan sonra dahi, yüzeydeki yayılma kritik sınır değerine ulaşmamıştır. Buradan üretilen deneme levhalarının TS EN-ISO 11925-2 standardına göre yanma malzeme sınıfına dahil edilebilir. Deneme levhalarının ısı yalıtım özellikleri incelendiğinde, alçı yapısına lignoselüloik hammaddenin ekllenmesinin olumlu katkı yaptığı anlaşılmıştır. Levha yapısında %10 dan daha yüksek atık kağıt eklenmesinin (A3-A6 levhalar) aynı üretim şartlarındaki atık oluklu mukavva (B tipi) ve sekonder lif esaslı (C tipi) deneme levhalarından daha yüksek ısı yalıtımı sağladığı anlaşılmıştır. Genel olarak ısı transfer ortalama değerleri kontrol örneğine göre daha iyi olduğu görülmüştür. İlginç olarak en yüksek ısı izolasyonu sağlayan örnek aynı zamanda en yüksek kütle kaybı göstermiştir. En yüksek kütle kaybı A tipi levhadalarda %3,52 (A6), B tipi levhalarda 3.46% (B6) ve C tipi levhalarda 3.28% (C8) olarak ölçülmüştür.

The effect of disinfectants on the accuracy, quality and surface structure of impression materials and gypsum casts: A comparative study using light microscopy, scanning electron microscopy and micro computed tomography

The aim of this study was to compare the effect of several commercially available disinfectants on the accuracy of various types of impression materials and their compatibility with gypsum including surface quality and structure evaluation. Four alginate and three elastomeric impression materials in combination with disinfectants Aseptoprint Liquid, Zeta 7 solution, Silosept and Dentaclean Form were tested. The dimensional changes, detail reproduction, the compatibility with gypsum and surface/subsurface morphology were evaluated using light microscopy, scanning electron microscopy and micro computed tomography. Two alginate materials disinfected in Dentaclean Form exhibited the most significant differences (p<0.0001). The loss of detail on some alginate impressions in combination with this disinfectant including deterioration and change of morphology of gypsum surfaces was observed. Porosity in subsurface area and exposed large particles were detected. It was confirmed that the desired properties of impressions may be negatively affected in combination with some disinfectants.

Properties of Gypsum Boards Made of Mixtures of Wood and Rice Straw

Aims: It was investigated to produce gypsum-based experimental composite panels with red pine wood/rice straw particles in the mixture up to 60:40 (ratio) (w/w) in gypsum-water mixture. In this case, the additives could be observed more closely.&#x0D; Methodology: The red pine wood chips and the rice straw (stalks) have been turned into suitable particle dimensions. The experimental boards were cut to determine the IB (Internal bond), MOE–MOR (Modulus of Elasticity and Rupture), and TS (thickness swelling after 24 hours immersion in water). A standard flame combustion test system was conducted according to TS EN-ISO 11925-2. For surface chemical analyses, FTIR was used to evaluate the chemical groups present in the board surface. The thermogravimetric analysis (TGA) was conducted for measuring changes in boards as a function of increasing temperature. The natural weathering tests were conducted that were exposed to outdoor for two months then color and surface hardness measurements conducted for determining property changes.&#x0D; Results: The rice straw had negative impact on thickness swelling (TS) properties of boards in water. The highest TS value of 47.66% was observed in the board that produced from 60:40 (ratio) (w/w) wood/rice straw mixture (DE4). However, the addition of rice straw to the wood/gypsum mixture has a lowering effect on the internal bond (IB) and bending strength (MOR) properties of experimental boards some level. The maximum IB strength of 0.06 N/mm2 and MOR of 2.77 N/mm2 found control sample (DE0). However, the highest MOE value of 553 N/mm2 was calculated on the DE4 board, which was produced by adding 40% rice straw to the wood/gypsum mixture. The addition of rice straw and wood particles to the gypsum structure has a positive effect on the heat transfer properties.&#x0D; Conclusion: It is clear that the addition of rice straw to the wood/gypsum mixture adversely affected the strength properties negatively. However, rice straw in wood chip/gypsum mixture helps to improve heat resistance (insulation) properties of panels at some level. Moreover, the addition of rice straw to wood/gypsum mixture effects on extending hardening time.

Atık Selülozik Karışımı Kaynaklardan Üretilen Alçı Esaslı Levhalar: 1. Bölüm. Fiziksel ve Mekanik Özellikler

It was realized that post-consumer waste paper, old corrugated container (OCC) and secondary fiber addition (cellulosic additives) to gypsum in panel structure negative impact on Thickness Swelling (TS) values in water. However, highest TS values of 23.32% (A6) in A-type, 12.76 (B6) in B-type and 7.79% (C6) in C-type experimental boards found at similar proportions (50:50 w/w) of gypsum and cellulosic additives while the lowest with control sample that was only 1.88%. Moreover, the boards produced by secondary fiber/gypsum mixture (C type boards) under similar ratios (w/w) were found to higher IB strength than others . The highest IB strength value of 0.60 N/mm 2 found for C3 board while the ratio of the secondary fiber in the mixture to be more than 20% negative effects on IB values ​​to a certain extent. The addition of all three cellulosic sources to the gypsum structure increases the bending strength properties some level. At 10% (A2: 6.59 N/mm 2 ) and 50% (A6: 6.44 N/mm 2 ) proportion levels, A-type boards show higher bending strengths than the B- and C-type boards. In all manufacturing conditions and board types, the natural weathered boards have always shown lower hardness properties than counterpart control samples.

Role of basalt dust in the formation of the modified gypsum structure

Waste disposal in the production of building materials and the organization of waste-free technological processes require a large amount of multilateral research. The application of basalt dust in the production of gypsum materials has been little studied. The paper investigated the effect of basalt dust - waste production of basalt fibers, on the working mixtures and the properties of hemihydrate of calcium sulfate paste (standard consistency, setting time of gypsum dough, water absorption of the resulting gypsum stone). It is known that the addition of basalt waste has a positive effect on strength, but there is no data on its effect on the rheological properties of gypsum mixtures. It was revealed that the introduction of basalt dust into the composition of the gypsum composite contributes to the change of the plaster mix rheology and of the properties of the gypsum structure. This must be taken into account when selecting optimized formulations of working mixtures on the hemihydrate of calcium sulfate.

Softening Damage Analysis of Gypsum Rock With Water Immersion Time Based on Laboratory Experiment

In view of the effect of water on the physical and mechanical parameters of natural gypsum rock, in this study, gypsum rock in the goaf of a gypsum mine was selected as the research object, and gypsum rock samples were prepared with different immersion times. In addition, uniaxially tests were performed separately on the gypsum rock samples. Compression and scanning electron microscopy experiments were carried out to analyze the effects of immersion time on the uniaxial compressive strength, elastic modulus, Poisson’s ratio, and microstructure of gypsum. The results show that the uniaxial compressive strength and elastic modulus of gypsum are inversely proportional to the water content. However, the Poisson’s ratio is direly proportional to the water content, and the failure mode is destroyed by the brittle fracture of a single crack and is transformed into the shear ductile failure of the Y-shaped crack. Microscopically, with increasing immersion time, the bonds in the crystal of the microporous cracks and microcrack tips are weakened by hydrolysis, and the macroscopic structure is complicated by the internal structure of gypsum, and the end of the crack is expanded by the compressive action of water. Based on the damage mechanics, the evolution equation of gypsum soaking softening damage based on time factor was derived. The relationship between the brittleness coefficient and softening damage variable is revealed, providing a theoretical basis for the determination of the softening degree of gypsum in the goaf.

Kinetics of plaster hydration and structure of gypsum: Experiments and kinetic Monte Carlo simulations with added gypsum seeds

Experiments and simulation results are compared in order to make precise the conditions optimizing both the kinetics of plaster hydration and the structure of the resulting material. Calorimetry experiments performed for different amounts of added gypsum seeds are used to assign values to the simulation parameters controlling kinetics, e.g. time step, surface density of gypsum germs on plaster grains. Simulation provides a reliable quantity to follow the beginning of setting, the fraction of gypsum needles belonging to a percolating cluster, as proven by comparing its evolution with the one of the elastic modulus during shear experiments. The simulations reveal that the beginning of needle growth may be hindered by two many small plaster grains, whereas big plaster grains slow down the end of the reaction. We suggest to add gypsum germs with an mg/mp=0.002 gypsum-to-plaster mass ratio in order to optimize homogeneity of the final material.

Structural evolution of gypsum under high pressure: single-crystal X-ray experiments revisited

The structures of gypsum at pressures up to approximately 4 GPa are studied with density functional theory (DFT) and thoroughly compared with single-crystal X-ray diffraction experiments reported in the literature [Comodi et al. in (Am Miner 93:1530–1537, 2008)]. It is found that the exchange–correlation density functional revPBE (revised Perdew–Burke–Ernzerhof) in conjunction with a nonlocal van der Waals (vdW) correction is capable of modeling the lattice constants, axial compressibility, and bulk modulus with good accuracy, suggesting that the inclusion of the vdW functional is crucially important for understanding the structure of hydrous minerals. To gain further physical insights, the geometric parameters associated with the constituting components of gypsum (water molecules, SO4 tetrahedra, and CaO8 polyhedra) are analyzed and compared with the experimental values. DFT simulations show that, under pressure, the polyhedral layers remain as nearly planar sheets of interconnecting SO4 tetrahedra and CaO8 polyhedra without further crinkling. DFT analysis on the layer compressibility along the major crystal axis reveals that, in contrast to experimental reports, the hydrous interlayer is less compressible than the polyhedral layer. Squeezed by the lateral pressure, the water molecules in the hydrous interlayer become better affixed along the major axis, making the interlayer harder to compress along this axis.

Examination of the structural characteristics arising in gypsums by the GPR and MASW methods (Sivas, Turkey)

This study was performed at an area of 50 × 48 m2 being defined as a new settlement in the northeast of Sivas. In the study, the discontinuities that are not deep and their geophysical characteristics were examined by the GPR and MASW methods. For interpretation, GPR cross sections were prepared as 2D–3D, and MASW cross sections were prepared as 2D. As for geophysical cross sections, about 10 m depth was examined. It was understood that the reflections observed in the form of hyperbolas in GPR cross sections correspond to areas having low S wave velocity (Vs) in MASW cross sections. It was understood that the S wave velocities are lower than 653 m/s, that the seismic velocities in between 653 and 275 m/s indicate partially deteriorated areas and that the S wave velocities of unweathered gypsums are higher than 1275 m/s at these low-velocity zones. Thus, it was thought that the fill material that may arise in the fracture, crack and deterioration areas arises from intercalation and clastic gypsum units, and that it plays a role in having low value S wave velocities. In all the geophysical cross sections, it was understood that the structures with gypsum are intense at the initial 5 m. And a fracture at the south of the study area, that it was estimated might be longer than 40 m, was determined as the largest gypsum structure. It was understood that this fracture starts from a depth of about 5 m in the west and that it slopes down to 7 m depth in the east. According to these results, it was understood that the damage amount arising in time in the gypsum structures from the effect of water may increase, the study area was defined as risky, and the required importance should be attached to these structures especially in foundation engineering.

Frame-Monolithic Technology of Construction of Low-Rise Buildings Made of Foam Gypsum and Steel Thin-Walled Structures

Frame-Monolithic Technology of Construction of Low-Rise Buildings Made of Foam Gypsum and Steel Thin-Walled Structures

The use of pulverized wastes of basalt production as a filler of gypsum compositions

These studies are aimed at improving the performance of gypsum materials and products by using in their composition waste production of basalt fibers. The purpose of this study is to prove the possibility of using waste production of basalt fibers as a filler in gypsum composites. As the main materials used gypsum binder (Samara), as well as waste production of basalt fibers (Tver production). The positive effect of the waste is due to the participation of soluble minerals of basalt in the processes of hardening of gypsum binder. Also, the waste particles form a more perfect structure of gypsum stone., filling the pore space. It is revealed that the use of waste production of basalt fibers is advisable to use as a filler in gypsum composites.

The influence of cellulose derivatives on water structure in gypsum

In this study the influence of cellulose derivatives modifiers: 2-hydroxyethyl methylcellulose (HEMC), hydroxypropyl methylcellulose (HPMC) and hydroxypropyl cellulose (HPC) on the gypsum setting process and their respective changes in water arrangement were analysed. IR spectroscopy revealed the differences in the water structure between the surface and the fracture of gypsum samples. In comparison to pure gypsum, the setting process is slower in the presence of cellulose derivatives as the hydrophilic polymer partially traps the water molecules. Through the comparison of IR, SEM, DSC and micro-mechanical measurements supramolecular model of gypsum structure containing cellulose derivatives which stabilized water clusters was proposed.