Mixture Of Gypsum Research Articles

Limits for the Identification of Smectites Mixed with Common Minerals Based on Short-Wave Infrared Spectroscopy

The identification of minerals, particularly clay minerals, using visible, near-infrared, and short-wave infrared (VNIR-SWIR) spectroscopy has gained prominence due to its efficiency and the advancement of remote hyperspectral sensors. However, identifying minerals in polymineralic samples remains challenging due to overlapping absorption features. This study prepared systematic binary mixtures of two smectites (dioctahedral and trioctahedral) with common non-clay minerals (calcite, dolomite, gypsum, quartz, and feldspar). Spectra from these mixtures were obtained using the ASD FieldSpec 4 Hi-Res spectroradiometer and analyzed with continuum removal and second derivative preprocessing to define detection limits. These limits indicate the minimum percentage of each mineral required for clear identification in various smectite–non-clay combinations. After continuum removal, smectites are identified at ≥5%–10% in mixtures with carbonates, quartz, and feldspar, but ≥70% is needed for gypsum. Non-clay minerals have detection limits of ≥70% for calcite and 20% for gypsum in the presence of smectites, while dolomite remains undetectable. The second derivative improves these limits, enabling smectite identification at 5% in carbonate mixtures and 5%–15% in gypsum mixtures. Calcite detection limits are 65%, and dolomite can be identified at ≥65% and ≥85% with dioctahedral and trioctahedral smectites, respectively. Gypsum detection limits are reduced to 10%, while quartz and feldspar cannot be identified due to lacking absorption features.

Rebuilding with sand roses: Cold sintering of sand-gypsum mixture for sustainable brick production

In the arid climate of the Sahara Desert, several historical cities dating back to the 16th century were constructed using bricks made from sand roses, a rosette-like rock composed of sand and gypsum. This study proposes the cold sintering of sand – dihydrate gypsum (uncalcined) mixtures as a sustainable approach to develop geomimetic sand roses with satisfactory mechanical performance. The results showed that crucial factors for enhancing the unconfined compressive strength (UCS) of the cold-sintered sand-gypsum mixtures are reducing gypsum size, utilizing cyclic loading, and applying higher pressures. Reducing sand size or introducing lubricant has minimal or negative effects. Cold-sintered sand-gypsum mixtures containing over 30 % micron-sized gypsum, subjected to cyclic pressures of 100 MPa for 15 minutes, can achieve superior UCS values compared to equidimensional concrete bricks. In addition, coating the mixture with calcium carbonate can be a viable approach for protecting against weathering agents. Coating and recycling the sand-gypsum mixture do not compromise the mechanical performance of the bricks. The proposed integration of sustainable materials and manufacturing practices has the potential to reduce costs, energy consumption, and industrial emissions, while promoting a circular economy and resource preservation. The proposed brick is referred to as “sand rose brick.”

Utilization of coconut fiber waste as a filling material for list profile

Abstract List profile is a mineral board product that is increasingly in demand by the wider public. One of the advantages of list profiles is that they are cheap, quick to obtain, resistant to attacks by wood-destroying organisms, and can be obtained in the form of attractive ornaments. From an economic perspective, list profile with rofing filler is more expensive. Coconut fiber can be used as a type of filler that has the same strength at a low price. This research aims to determine the type and level of gypsum adhesive, white cement, and their mixtures on the properties of the coconut fiber list profile. The research design used a completely randomized design with Tukey’s follow-up test. The factors used were the type of adhesive (gypsum, white cement, and a mixture of gypsum with white cement), and the amount of adhesive (600 g, 690 g, and 780 g). The parameters observed were water content, density, thickness expansion, and fracture toughness. The research results showed that the type of adhesive had a significant effect on water content and thickness development, the amount of adhesive had a significant effect on density and the adhesive type had a significant effect on water content, while the amount of adhesive had a significant effect on density and thickness development. The average value of water content is 15.90 - 18.85 %, density 0.67 - 0.92 g/cm3, thickness expansion 0.37 - 2.54 % and strength at fracture 3.88 - 35.90 kg/cm2.

Effect of ratio of desulfurization gypsum to carbide slag on low-carbon phase change composites for energy storage

To recycle industrial wastes sufficiently, this work innovatively proposed a mixture of desulfurization gypsum and carbide slag as skeleton material to fabricate phase-change composites with NaNO3 as phase change material in a mass ratio of 5 to 5. Four phase-change composites were fabricated with different ratio of desulfurization gypsum to carbide slag by the cold compression-hot sintering method, and then key thermal and mechanical properties, microscopic morphology and chemical compatibility between components were investigated in detail. Results show that the mixture of desulfurization gypsum and carbide slag as skeleton material is feasible and reliable and an optimal mass ratio of desulfurization gypsum to carbide slag was obtained to be 3.5 to 1.5; the phase-change composite with the optimal mass ratio possesses good mechanical strength of up to 134.116 MPa and an energy storage capacity of 483.151 J/g in the range of 100 to 400 °C, as well as excellent thermal stability and chemical compatibility between components, inside which the NaNO3 is well encapsulated. Moreover, the phase-change composites fabricated in this work have far low energy consumption and carbon dioxide emission.

Topography of root-end surface after freehand and three-dimensional-guided apicoectomy procedure: A scanning electron microscope study.

Dentinal microcracks formed during apical resection may lead to increased susceptibility to root fracture and improper sealing of apical preparation that may negatively influence the outcome of endodontic microsurgery. This study was performed to analyze the root-end surface for dentinal microcracks using a scanning electron microscope (SEM) after resection with high-speed bur and trephine drill. Thirty extracted single-rooted maxillary premolar teeth were selected and randomly distributed into two groups (n = 15). Working length was established using a #15 K-type file. Canals were prepared with a rotary Ni-Ti system to size 30/0.06 using endomotor, irrigated with 3% sodium hypochlorite, dried with paper points, and obturated with gutta-percha cones using a single-cone technique. All samples were mounted on preformed molds and poured using a mixture of sawdust and gypsum. In Group A; tungsten carbide bur was used to perform a freehand apicoectomy. In Group B; a trephine drill was used with a three-dimensional guide to perform 3 mm of root resection. Apicoectomy was performed in both groups under a dental operating microscope. Resected root ends were inspected for microcracks using SEM. The Shapiro-Wilk and Mann-Whitney U-test were used for statistical analysis. Microcracks were observed in all samples in both study groups. Trephine drill produced more microcracks on the resected root surface compared to the use of high-speed tungsten carbide bur with a statistically significant difference (P < 0.05). The trephine drill used during targeted endodontic microsurgery produced more microcracks on the resected root dentine surface compared to the high-speed tungsten carbide bur used during freehand apicoectomy.

Brevipalpus yothersiBaker (Tenuipalpidae) development in sweet orange plants is influenced by previous mite infestation and the presence of shelters.

Citrus leprosis is the most important viral disease affecting citrus. The disease is caused predominantly by CiLV-C and is transmitted by Brevipalpus yothersi Baker mites. This study brings some insight into the colonization of B. yothersi in citrus [(Citrus × sinensis (L.) Osbeck (Rutaceae)] previously infested by viruliferous or non-viruliferous B. yothersi. It also assesses the putative role of shelters on the behavior of B. yothersi. Expression of PR1 and PR4 genes, markers of plant defense mechanisms, were evaluated by RT-qPCR to correlate the role of the plant hormonal changes during the tri-trophic virus-mite-plant interplay. A previous infestation with either non-viruliferous and viruliferous mites positively influenced oviposition and the number of adult individuals in the resulting populations. Mite populations were higher on branches that had received a previous mite infestation than branches that did not. There was an increase in the expression of PR4, a marker gene in the jasmonic acid (JA) pathway, in the treatment with non-viruliferous mites, indicating a response from the plant to their feeding. Conversely, an induced expression of PR1, a marker gene in the salicylic acid (SA) pathway, was observed mainly in the treatment with viruliferous mites, which suggests the activation of a plant response against the pathogen. The earlier mite infestation, as well as the presence of leprosis lesions and a gypsum mixture as artificial shelters, all fostered the growth of the B. yothersi populations after the second infestation, regardless of the presence or absence of CiLV-C. Furthermore, it is suggested that B. yothersi feeding actually induces the JA pathway in plants. At the same time, the CiLV-C represses the JA pathway and induces the SA pathway, which benefits the mite vector.

Preparation and Performance Study of Alkali-active Gypsum Mixture System

To improve the mechanical properties and water resistance of gypsum specimens, thus solving the pollution problem due to the accumulation of flue gas desulfurization gypsum (FGD gypsum), etc. The article utilizes flue gas desulfurization gypsum, gypsum citrate, and mineral powder as the main raw materials under a fixed ratio. The Alkali-activation gypsum-based cementitious material (Alkali-activation GM-S95 system) was obtained by modifying it with 0-5% Na(OH) and Ca(OH)2 alkaline admixtures, and the mechanical properties and water resistance of the Alkali-activation GM-S95 system were thoroughly investigated. The structural characteristics of the Alkali-activation GM-S95 system specimens were investigated using XRD, TG, SEM and LF-NMR techniques to explore their interactions. The results showed that the compressive strength of the Alkali-activation GM-S95 system was significantly increased to 26 MPa when 4% Ca(OH)2 was added alone, and the water absorption was decreased to 12.5%.The addition of 4% Ca(OH)2 caused the crystals of gypsum dihydrate to be thicker and denser, and AFT and C-S-H gels were produced, which were attached around the crystals of gypsum dihydrate. The addition of different admixtures can reduce the proportion of large pores and further fill the crystal structure. In summary, the addition of 4% Ca(OH)2 can improve the compressive strength and water resistance of the samples of Alkali-activation GM-S95 system, thus laying a solid foundation for the comprehensive utilization of flue gas desulfurization gypsum.

Influence of steel fiber (SF) addition on the enhancement compressive strength of pure gypsum

This research examines how reinforcing pure gypsum with steel fiber (SF) changes its compressive strength. Six pure gypsum-only mixtures will be used in the study. There are two groups of these mixtures, with water-to-gypsum ratios of 0.6 and 0.7, respectively. Steel fiber volume fractions of 0 %, 0.15 %, and 0.3 % were used to subdivide each group into three subgroups further. For every group, three samples were taken in 50x50x50 mm cubes. Steel fibers added to pure gypsum mixtures were shown to boost compressive strength for both water/gypsum ratios, with the percentage increase increasing with the water/gypsum ratio. However, the compressive strength decreases for all volume fractions of steel fiber as the water/gypsum ratio rises.

Experimental investigation of the rock cutting process and derivation of the 3D spatial distribution of the formation strength using in-cutter sensing

Recent advances in downhole measurements allow to accurately measure drilling forces at the drill bit, and estimate the evolution of the rock strength along the well profile. This paper presents an experimental methodology that allows to measure drilling forces, at the cutter scale, with a sensor embedded behind a polycrystalline diamond compact (PDC) cutter, and to infer the 3D spatial distribution of the rock strength. Two experimental campaigns have been performed on a laboratory-scaled drilling rig and complemented with standard mechanical tests to validate rock strength estimations. In the first campaign, homogeneous synthetic rock samples have been prepared. The average rock strength of each sample derived from cutter force measurements and a cutter–rock interaction model, compares well with the one derived from mechanical tests. In the second campaign, heterogeneous synthetic rock samples have been prepared. They are made of two layers of gypsum mixtures of different strengths, separated by a slanted bedding plane. Based on the instrumented cutter measurements, the 3D spatial distribution of the rock strength has been reconstructed along its path. Rock strength estimations are consistent with results obtained from mechanical tests, and the reconstructed geometry of the bedding plane matches well its actual geometry. The experimental methodology and technology presented in this paper lay the foundations for estimating rock properties in 3D, at the drilling stage. It has the potential to provide geoscientists information about complex lithological structures at an early stage, reducing the need for expensive and time-consuming coring and logging operations.

CHARACTERIZATION OF A GRECO-ROMAN STUCCO MASK (REG. NO. 229) PRESERVED AT THE NATIONAL MUSEUM OF EGYPTIAN CIVILIZATION, CAIRO, EGYPT

The Greco-Roman stucco masks are of great historical, artistic and religious importance. According to the restoration-conservation strategies, the detailed mineral characterization of artifacts is an important step that facilitates the selection of appropriate restoration procedures. Different characterization techniques such as USB digital microscope, scanning electron microscopy–energy dispersive X-ray analysis, X-ray diffraction analysis (XRD), thermal analysis (DTA/DTG), Fourier transform infrared and micro-Raman spectroscopies were used. The results indicated that gypsum is the main component of the stucco mask. As well, calcite was found as an impurity or an addition together with halite and anhydrite as deterioration products. The iron nail corrosion was the reason for a notable discoloration to the stucco mask. FTIR analysis confirms that animal glue is the adhesive material used for the reassembly of the mask. The used pigments for painting the mask are hematite for red-orange color, mixture of hematite and magnetite for brown color and mixture of gypsum and hematite for the white brown color.

Semi-quantitative measurement of calcium carbonate in historic gypsum mortars, using diffuse reflectance infrared Fourier transform spectroscopy

This paper uses Fourier transform infrared spectroscopy to semi-quantitatively measure the amount of calcium carbonate in historical gypsum mortars. 17 historical mortar samples related to Arch of Alishāh in Tabriz-Iran, belonging to the Ilkhanid period, were evaluated. The methodology used in this study was diffuse reflectance infrared Fourier transform spectroscopy [DRIFTS]. Gypsum mortars containing 0-6.5% calcite were prepared and analysed using an FTIR spectrometer. The calibration curve was prepared based on the band intensity ratio of 1485 cm-1 related to carbonate vibrations in calcite to 660 cm-1 corresponding to sulphate vibrations in gypsum. Calculating the amount of carbonate in all historical mortars shows the presence of about 0.12 to 1.08% carbonate in gypsum mortar. According to obtained results, it can be acknowledged that due to the meagre amount of carbonate in the mixture of mortars, the existing carbonate has entered the mortar as an impurity through soil or dissolved salts. This can indicate that, contrary to the initial idea about some of these mortars, lime and gypsum mixture was not used as the main component in the making these mortars.

The mixture of Radix isatidis, Forsythiae, and Gypsum alleviates lipopolysaccharide-induced fever in broilers by inhibition of TLR4/NF-κB signaling pathway

To determine whether the antipyretic effect of the mixture of Radix isatidis, Forsythiae, and Gypsum (RIFG) on lipopolysaccharide (LPS) induced fever broilers and its related mechanisms. A total of 315 24-day-old yellow-plumed broilers were randomly divided into 7 groups, except for the control group, other groups were injected with LPS. Two hours later, RIFG were given drinking water to relieve fever, and it was evaluated by the expression of genes and proteins of the maximum body temperature rise (∆T), body temperature response index (TRI), serum and hypothalamic pyrogenic heat factor. RIFG could reduce the body temperature of broilers with fever (P < 0.01). It inhibited the expressions of IL-6 and PGE2 (P < 0.01), down-regulated mRNA expression levels of TNF-ɑ and COX-2 (P < 0.01), and promoted the generation of antipyretic factor AVP mRNA (P < 0.01). In addition, the expression level of TLR4 and NF-κB p65 protein can be down-regulated, and LPS+RM group has the best down-regulated effect. RIFG had a good antipyretic effect on reducing LPS-induced fever of broilers by inhibiting the activation of TLR4/NF-κB signaling pathway and thermogenic factors.

Dependence of mechanical and thermal properties on the composition of lightweight gypsum composites

One of the ways to use the treated gypsum waste is in gypsum mixtures for the production of gypsum blocks. Gypsum blocks can be used in standard interior as well as exterior applications and are made of gypsum, water, PP microfibres and are lightened with foam, which is created from a foaming additive and water. Above all, the amount of foam significantly influences the bulk density of the resulting material, and the bulk density then has a major influence on the mechanical and thermal properties. The use of PP microfibres had a positive effect on the overall stability of the foamed structure, which resulted in an increase in compressive strength while maintaining good thermal insulation properties.

Comparative assessment of physical and mechanical indicators of packing materials of complete removable dentures

Successful dental rehabilitation of a patient with complete removable dentures depends not only on a number of features of the selected design and clinical conditions of the patient's prosthetic area. Also on the manufacturing technology of the materials used for its manufacture. The purpose of our study was a comparative assessment of the physical and mechanical properties of doped packing materials for removable denture structures using an improved method. An alloyed packing material based on gypsum and supergypsum, modified with nitrile rubber latexes and organosilicon emulsion, was developed. The selected modifiers differ in their structure, group polarity and lyophilicity. The comparative analysis of the quality of auxiliary dental materials included a generalization of the results of a laboratory study of the physical and mechanical properties of various types of plaster. In the system of qualitative assessment of plasters, the indicative properties of auxiliary materials were investigated: "ORTHOGYPS", "Gypsum highness type 10", "Base Stone", provided by ISO 6873, which are divided by us into technological (defining features of the material packaging process) and physical and mechanical (total working time, structuring time, relative expansion during structuring, relative expansion after structuring, compressive strength, linear shrinkage). As a result, it was determined that the developed modified components of the alloy packing material, in turn, provided acceptable accuracy of the base of the removable dentures, which corresponded to the working model due to the improvement of the physical and mechanical properties of the packing material and, as a result, improved manufacturability of removable orthopedic structures of dental prostheses. Keywords: orthopedic treatment, physical and mechanical properties, complete removable dentures, modifier, gypsum mixture.

The Use of Aluminosilicate Ash Microspheres from Waste Ash and Slag Mixtures in Gypsum-Lime Compositions.

The article considered the issues of the modification of gypsum stone to improve its performance properties. The influence of mineral additives on the physical and mechanical characteristics of the modified gypsum composition is described. The composition of the gypsum mixture included slaked lime and an aluminosilicate additive in the form of ash microspheres. It was isolated from ash and slag waste from fuel power plants as a result of their enrichment. This made it possible to reduce the carbon content in the additive to 3%. Modified compositions of the gypsum composition are proposed. The binder was replaced with an aluminosilicate microsphere. Hydrated lime was used to activate it. Its content varied: 0, 2, 4, 6, 8 and 10% of the weight of the gypsum binder. Replacing the binder with an aluminosilicate product for the enrichment of ash and slag mixtures made it possible to improve the structure of the stone and increase its operational properties. The compressive strength of the gypsum stone was 9 MPa. This is more than 100% higher than the strength of the control composition of gypsum stone. Studies have confirmed the effectiveness of using an aluminosilicate additive-a product of enrichment of ash and slag mixtures. The use of an aluminosilicate component for the production of modified gypsum mixtures allows the saving of gypsum resources. Developed formulations of gypsum compositions using aluminosilicate microspheres and chemical additives provide the specified performance properties. This makes it possible to use them in the production of self-leveling floors, plastering and puttying works. Replacing traditional compositions with a new composition based on waste has a positive effect on the preservation of the natural environment and contributes to the formation of comfortable conditions for human habitation.

Thermal and Sound Characterization of a New Biocomposite Material.

Bio-based composites are increasingly used. One of the most frequently used materials is hemp shives, which is agricultural waste. However, as the quantities of this material are lacking, there is a tendency towards finding new and more available materials. Corncob and sawdust are bio by-products that have great potential as insulation materials. In order to use these aggregates, it is necessary to examine their characteristics. New composite materials based on sawdust, corncobs, styrofoam granules, and the mixture of lime and gypsum as the binder were tested in this research. This paper presents the properties of these composites obtained by determining the porosity of samples, volume mass, water absorption, airflow resistance and heat flux, which was followed by the calculation of the thermal conductivity coefficient. Three of the new biocomposite materials, whose samples were 1-5 cm thick for each type of mixture, were investigated. The aim of this research was to analyze the results of different mixtures and sample thicknesses in order to determine the optimum composite material of the proper thickness so that the best possible thermal and sound insulation could be obtained. Based on the conducted analyses, the biocomposite with a thickness of 5 cm, composed of ground corncobs, styrofoam, lime, and gypsum, proved to be the best in terms of thermal and sound insulation. New composite materials can be used as an alternative to conventional materials.

MP68-02 WHAT ARE THE OPTIMAL LASER SETTINGS FOR STONE DUSTING USING THE POPCORN TECHNIQUE

You have accessJournal of UrologyCME1 Apr 2023MP68-02 WHAT ARE THE OPTIMAL LASER SETTINGS FOR STONE DUSTING USING THE POPCORN TECHNIQUE Oleksandr Chepeliuk, Asaf Shvero, Dorit Zilberman, Zohar Dotan, and Nir Kleinmann Oleksandr ChepeliukOleksandr Chepeliuk More articles by this author , Asaf ShveroAsaf Shvero More articles by this author , Dorit ZilbermanDorit Zilberman More articles by this author , Zohar DotanZohar Dotan More articles by this author , and Nir KleinmannNir Kleinmann More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003331.02AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: When evoking stones with a laser (Dusting) it is common to use the "popcorn" technique to complete the dusting. Today there are advanced and much more powerful laser machines, which allows the use of a variety of intensities, rates, and modulations. The purpose of the study is to check what are the most effective holmium laser settings while performing the popcorn technique. METHODS: Stones were brewed from gypsum mixtures in three density levels. Their density was measured by CT imaging. 5 stones of size 2.8-3.3 mm were filtered and put into test tubes, and their weight was measured. Under continuous washing, "popcorn" stone dusting was performed with a holmium laser using a 272 micron fiber, using the popcorn technique for 2 minutes at intensities 0.3J/80Hz, 0.5J/40Hz, 1J/20Hz, 1J/ 30Hz, 1.5J/20Hz. With/without Moses modulation (distance). 3 repetitions were performed for each intensity. The mass of the remaining stone was weighed, and the stones larger than 1 and 2 mm were counted. The efficacy and evaporation rates of the stones were compared. RESULTS: The density of the hard, medium and soft stones was 2095,995,548 HU respectively. The average rate of evaporation in soft, medium and hard stones was 68%, 50%, 47%. In soft stones it was found that the rate of vaporisation was the largest in the laser settings of 1J/30Hz without Moses (93%). There were no stones >2 mm left, and the number of crumbs between 1-2 mm was 3. In medium density stones, the rate of vaporisation was the greatest in the settings 1.5J/20Hz with Moses (71%). No stones >2 mm remained, and the number of stones between 1-2 mm was 3. In hard stones, it was found that the rate of vaporisation was the greatest in the laser settings of 1J/30Hz with Moses (76%). There were no stones >2 mm left, and the number of stones between 1-2 mm was 7. Moses modulation did not change the total vaporisation rate (p=0.256). CONCLUSIONS: When using the "popcorn" technique for laser dusting of kidney stones, we found different efficiency rates between the different laser settings. The most effective laser settings were in soft stones 1J/30Hz without Moses, in medium 1.5J/20Hz with Moses, and in hard stones 1J/30Hz with Moses. Source of Funding: Sheba Medical Center © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e952 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Oleksandr Chepeliuk More articles by this author Asaf Shvero More articles by this author Dorit Zilberman More articles by this author Zohar Dotan More articles by this author Nir Kleinmann More articles by this author Expand All Advertisement PDF downloadLoading ...

Investigation of Gamma-Ray Shielding Properties of Bismuth Oxide Nanoparticles with a Bentonite–Gypsum Matrix

Due to the present industrial world, the risk of radioactivity is notably increasing. Thus, an appropriate shielding material needs to be designed to protect humans and the environment against radiation. In view of this, the present study aims to design new composites of the main matrix of bentonite-gypsum with a low-cost, abundant, and natural matrix. This main matrix was intercalated in various amounts with micro- and nanosized particles of bismuth oxide (Bi2O3) as the filler. Energy dispersive X-ray analysis (EDX) recognized the chemical composition of the prepared specimen. The morphology of the bentonite-gypsum specimen was tested using scanning electron microscopy (SEM). The SEM images showed the uniformity and porosity of a cross-section of samples. The NaI (Tl) scintillation detector was used with four radioactive sources (241Am, 137Cs, 133Ba, and 60Co) of various photon energies. Genie 2000 software was used to determine the area under the peak of the energy spectrum observed in the presence and absence of each specimen. Then, the linear and mass attenuation coefficients were obtained. After comparing the experimental results of the mass attenuation coefficient with the theoretical values from XCOM software, it was found that the experimental results were valid. The radiation shielding parameters were computed, including the mass attenuation coefficients (MAC), half-value layer (HVL), tenth-value layer (TVL), and mean free path (MFP), which are dependent on the linear attenuation coefficient. In addition, the effective atomic number and buildup factors were calculated. The results of all of these parameters provided the same conclusion, which confirms the improvement of the properties of γ-ray shielding materials using a mixture of bentonite and gypsum as the main matrix, which is much better than using bentonite alone. Moreover, bentonite mixed with gypsum is a more economical means of production. Therefore, the investigated bentonite-gypsum materials have potential uses in applications such as gamma-ray shielding materials.

Leaching Behaviour of Synthetic Leachate through a Sewage Sludge and Red Gypsum Composite as Intermediate Landfill Cover

This paper examines the environmental impact of the use of compacted sewage sludge:red gypsum (SS:RG) mixture as intermediate landfill cover in terms of yield and quality of leachate as characterised by hydraulic conductivity and leaching behaviour. A series of column tests using the constant head method is carried out by percolating the synthetic leachate through samples that have been compacted at various degrees (60, 70, 75, 80 and 85%). The leachate quality is monitored at pre-determined days for pH, COD, Cu, Fe and Zn. In general, hydraulic conductivity decreases in three stages, in which the first stage is mainly attributed to the particle rearrangement and hydration of calcium silicate hydrate (CSH). The hydration of CSH increases the pH, which causes the heavy metal to precipitate and be entrapped within the matrices of CSH gel, thereby further reducing the porosity and hydraulic conductivity. A minimum of 75% compaction has shown favourable final porosity, hydraulic conductivity, and leachate quality, although a minimum of 80% compaction is recommended in order to achieve a satisfactory compressive strength of greater than 345 kPa for a landfill operation.

Upcycling of FGD Gypsum into a Product to Reduce Interrill Erosion: A Study Assessing Methods of Soil Surface Application

Soil conditioners have shown benefits in the reduction of soil erosion. A concomitant application of gypsum and polyacrylamide promotes aggregate stability and reduces the amount of runoff discharge and soil losses. Synthetic gypsum produced from flue gas desulfurization (FGD) at coalfired power plants has the potential to serve as a more sustainable source for the agricultural application of this soil conditioner. Upcycling of FGD gypsum into a pellet of a mixture of ground FGD gypsum and polyacrylamide (PAM) was compared to other types of soil surface application methods. Results confirm that surface application of PAM and FGD gypsum reduced soil erosion. Depending on the type of application method, addition of PAM and FGD gypsum presented different effects on the local hydrological processes and microtopography. Though PAM in solution acts as a physical net on the soil surface, the amount of water needed for its application makes it impractical for agricultural fields. Granular application of PAM and FGD gypsum, as well as pellets (upcycled product) has been shown to have a delayed effect in reducing soil erosion, as these methods required PAM particles to be activated. The upcycled product of FGD gypsum and PAM in the form of pellets demonstrates that the sudden expansion of the pellets due to PAM hydration results in the rapid release of the gypsum grains, providing a better treatment on the soil surface. Moreover, the increased surface area of PAM and gypsum due to the grinding is advantageous for a more rapid activation of the soil conditioners. The upcycled product of FGD gypsum and PAM is a practical application method that could be adapted by farmers to be used at field scale.