Gypsum Stone Research Articles

Biocidal properties of gypsum stone modified with Reynoutria sachalinensis raw materials

The current stage of the construction industry development implies increased requirements for building materials to maintain and improve global environmental processes. The understanding by ecologists globally of the danger of anthropogenic impact on the global environment has been reflected in the formulation of Sustainable Development Goals (SDGs). Thus, scientists and engineers are turning to safe plant-based raw materials as innovative building materials. Of particular interest for practice is the use of Reynoutria sachalinensis, which may exhibit biocidal properties. The purpose of this study was to obtain a gypsum stone modified with an extract from the green mass of R. sachalinensis, as resistant coating to fouling by microscopic fungi. The results indicated 10% decrease in the required water addition to gypsum paste when using plant extract, a slowdown of the initial and final setting time of the modified gypsum paste samples compared to the control samples by 6 and 7 min, respectively, and a slight decrease in bending and compressive strengths of the samples of 12.5% and 6%. The 100% resistance of the modified samples to fouling by microscopic mould fungi was also revealed.

Drill bit hydraulic system for oil and gas boreholes

We set out to improve the existing design of a polycrystalline diamond bit with a steel or matrix body with the purpose of creating a hydro-monitoring effect. The research object was the hydraulic system of a diamond bit with a near-bit jet pump. The near-bit ejector system was studied by a theoretical analysis of the operation of the bit hydraulic system by means of canonical dependencies and hypotheses. A hydraulic system for a polycrystalline diamond bit is proposed. This system includes a high-pressure jet pump, which enhances the hydro-monitoring effect at the bottomhole. The main hydraulic characteristics of the bit flushing system with a jet pump are as follows: at a drilling pump feed of 18.4 l/s and a drilling fluid density of 1180 kg/m3, the working coefficient of jet pump injection equals 0.34; the working nozzle diameter equals 10.3 mm; the mixing chamber is 11.9 mm, bit hydromonitor nozzles are 11.1 mm; the number of hydromonitor nozzles is 3; the velocity at the exit of hydromonitor nozzles is 85.0 m/s; the pressure drop at the bit is 15.7 MPa. The possibility of using the hydro-monitoring effect enhanced by a near-bit jet pump was substantiated, since the velocity at the exit from the hydro-monitoring nozzles is sufficient to destroy most rocks (sandstone, limestone, dolomites, rock salt, gypsum stone, basalt, marble, granite). The jet pump in the proposed design of a polycrystalline diamond bit creates an additional circulation circuit above the bottomhole, injects cuttings from the annular space and feeds them to the hydro-monitor nozzles. This enables a more efficient destruction of the bottomhole rock. The power of hydro-monitor jets is sufficient to improve drilling performance.

Role of Gypsum Stone to improve some physical and Hydrological Properties of heavy soil and yield of Sunflower Helianthus annuus L.

Role of Gypsum Stone to improve some physical and Hydrological Properties of heavy soil and yield of Sunflower Helianthus annuus L.

Profiling Novel, Multifunctional Silane-Phosphonate Consolidants for the Mitigation of Gypsum Stone Deterioration via Concerted Autocondensation/Surface Complexation Processes.

Mineral gypsum (selenite) stones have been used extensively by ancient Cretans in the Minoan Palace of Knossos (Crete, Greece), mostly for building and ornamental purposes. Exposure of mineral gypsum to environmental stresses (temperature fluctuations, rain, air-borne pollutants, soluble salts, etc.) causes solubility-driven degradation, and loss of cohesion of the crystal aggregates, with ensuing aesthetic degradation. In this work, the efficiency of four consolidants for artificial gypsum specimens is presented and evaluated based on drilling resistance measurements [drilling resistance measuring system (DRMS)]. Two of them (commercial names RC-70 and RC-90, RC = Rhodorsil Consolidante) are alkoxysilane-based and they are considered as benchmark consolidants. The other two [3-(trihydroxysilyl)propyl methylphosphonate monosodium salt, TRIMEPHONA, and 3-(trihydroxysilyl)propylamino-diphosphonate, TRIPADIPHOS] are multifunctional consolidants because they possess a self-condensable (after hydrolysis) trihydroxysilyl [-Si(OH)3] moiety and phosphonate groups (one in the former, two in the latter). Consolidants RC-70 and RC-90 exhibit rather low consolidation effectiveness. This is not unexpected, as these are alkoxysilane-based and act simply as "fillers" for the pores of the gypsum. Consolidant TRIMEPHONA demonstrates an enhanced level of consolidation action. This is due to its double functionality, i.e., the presence of an anionic phosphorus-based moiety that anchors onto the gypsum surface, and a condensable silane triol [-Si(OH)3] unit. Consolidant TRIPADIPHOS shows excellent gypsum consolidation features and is much more efficient (per unit concentration) than all other tested consolidants. This is assigned to its better gypsum anchoring ability via surface Ca-complexation. Selected compressive strength studies were performed on gypsum samples treated with the phosphorus-based consolidants, and corroborate the findings from DRMS. To shed further light on possible binding modes of the phosphonate moiety on surface Ca2+ sites in gypsum, two model compounds were synthesized and structurally characterized, Ca-C2D and Ca-C3D (C2D = ethylamino-di(methylenephosphonic acid) and C3D = propylamino-di(methylenephosphonic acid).

Processing of gypsum-bearing materials in the bronze age Gonur Depe archeological site (Southeast Karakum Desert)

The technology of preparation of an ancient binder mixture used in construction work at the Gonur Depe archeological site (Southeast Karakum desert) is interpreted on the basis of study of its mineral composition and textural-structural features. The material is composed of thin prismatic-angular and fbrous aggregates of reduced gypsum (60–70 %) and β-bassanite (3 %) enclosed in clay-siliceous matrix (20–30 %). The mixture also contains grains of quartz (5–10 %), feldspar (up to 1%), mica (up to 1 %) and other minerals. The mixture was produced from a crushed natural gypsum stone, which was calcinated in air. In this case, gypsum is converted to β-bassanite and partly to anhydride. The morphology and sizes of mineral particle confrm the presence of the calcination stage up to 200 °C. The further addition of water to a dry mixture caused rapid thickening and cementation of the material, which could be used for whitewashing and plastering of the walls.

Effective Method of Improving the Performance Properties of Wall Products On the Basis of the Gypsum Binder

The basis of the conducted research was the goal of modifying composite gypsum-containing binders for the manufacture of wall products with increased water resistance, strength, frost resistance, and durability by developing a hydrophobizing solution for processing products based on gypsum binder. The article presents the results of research on the modification of artificial gypsum stone with a developed hydrophobizing chemical solution based on calcium polysulfide and titanium dioxide. Comparative indicators of water absorption of original and solution-impregnated samples, which were exposed to the frontal influence of water, are given. The water absorption of the modified samples is within 9...21% and does not change after the frontal impact of rain. Indicators of chemical resistance of impregnated samples in solutions of magnesium sulfate, urea, acetic and oxalic acids, which are characteristic components for aggressive environments of livestock complexes, food and chemical industry, are presented. The test results of the samples showed that the developed chemical solution provides a chemical resistance factor of 0.7, that is, they are chemically stable in such environments. It is shown that, depending on the number of applied layers of the solution or the time of impregnation, hydrophobization gives high indicators of the softening coefficient of the products, which is in the range of 0.6...0.82. The research results showed that thanks to the developed hydrophobizing solution, the construction and technical characteristics of the artificial gypsum stone are significantly increased. Wall products made of this material have high operational characteristics, and it is advisable to use them both indoors and outdoors.

ПОВЫШЕНИЕ ЭКСПЛУАТАЦИОННЫХ ХАРАКТЕРИСТИК ГИПСОВОГО КОМПОЗИТА ДЛЯ ДЕКОРАТИВНЫХ ИЗДЕЛИЙ

The article discusses the results of research on the use of modifying additives in gypsum binder. Regulation of the structure and, therefore, the properties of gypsum stone can be carried out using small quantities of highly active additives that can effectively influence the formation of the structure of gypsum stone, and, consequently, its characteristics. Using functional modifying additives in small quantities, which practically do not affect the cost of the material, and using them to control the composition of gypsum binders, it is possible to obtain effective decorative and finishing gypsum products with improved characteristics.
 The work studied the effect of polyvinyl acetate additives together with synthetic polypropylene fiber on the properties of gypsum stone products. A comparison of the physical and mechanical characteristics of modified gypsum composites is presented, and the advantages of introducing fiber are revealed. By covering the pores and capillaries of gypsum stone with fiber fibers, the formation of shrinkage microcracks is significantly reduced, crack resistance increases, and strength characteristics increase.
 It has been established that modification of gypsum stone with polyvinyl acetate together with synthetic fibers helps to improve the physical and mechanical characteristics of gypsum stone. The developed compositions of decorative and finishing gypsum tiles using the additions of polyvinyl acetate and polypropylene fiber make it possible to obtain gypsum finishing materials products with improved characteristics, which demonstrates their increased efficiency as a modern finishing material and opens up broad prospects for use in housing and civil construction.

Metakaolin as an effective additive in the production of AAC

AbstractThe paper presents a study of the current state of autoclaved aerated concrete production. Global trends of autoclaved aerated concrete market confirm the tendency to reduce the density of wall blocks from 400–500 kg/m3 to 300–350 kg/m3. At the same time their strength level is required to be maintained. The search for inexpensive and available local effective pozzolanic additives may increase the economic and ecological attractiveness of AAC production.The performed studies have shown that using metakaolin additive helps to reduce energy consumption for AAC production. As a result of the research it was found that metakaolin can act as an alternative component of binder in aerated concrete mixture and replace gypsum additive. Metakaolin in the low density aerated concrete mixture stabilizes the processes of macrostructure formation of raw AAC. Performing functions of gypsum stone, this additive has a positive effect on the strength of the aerated concrete.Industrial tests have shown that the efficiency of metakaolin additive increases as the density of the aerated concrete decreases. The greatest effect of use of additive metakaolin is noted in concrete mixtures of low density (130‐150 kg/m3). It is advisable to introduce the additive into the aerated concrete mixture together with other components at the stage of mixture formation.

Engineering Assessment and Recycling of Building Stones Produced from the Destroyed Buildings in Old Mosul City

Building stones have various mineralogical, textures, microstructures, and physical and mechanical properties. Limestone, dolomite, and gypsum stone samples were taken from the old city of Mosul, which was destroyed due to the liberation operation of the city. From the study of the rock segments, it appeared that there was a low percentage of the pores that were formed due to the dissolution process, as well as the effect of weathering was a few centimeters in depth. From the results of the physical tests of the samples, it appeared that the density of the limestone is low to high for the grey gypsum. The grey gypsum has zero porosity, while low in gypsum and medium to high in dolomite and limestone, respectively. The rate of forced water absorption varies, and the reason is the difference in the porosity as it increases with connected pores, which in term leads to an increase in the amount of absorbed water. According to the results of the mechanical tests of the rocks, the compressive strength was low to medium, and the durability of the rocks was high, this confirms the validity of the rocks in the study area as unloading bearing stones. The economic feasibility results from not transporting the old rocks, but rather using them in the same site in the city. These huge quantities of stones, which took a great deal of work and money to bring to the city from the outskirts, cannot be wasted by transporting them outside the city because it will cause significant pollution and cost time and money, whereas they can be used in the reconstruction of the destroyed city, for instance, unloading bearing stones.

EXAMINATION OF NEW GROWTHS IN MODIFIED SULFATE-BASED COMPOSITES BY SCANNING ELECTRON MICROSCOPY

The structure of a gypsum matrix, which is characterized by the size, shape, and morphology of crystals, the state of the interfacial surface, and the number and strength of contacts between new growths, determines the basic physical and technical properties of materials. The effect of various modifiers, mainly of technogenic origin, on the gypsum stone structure has been examined by scanning electron microscopy and energy-dispersive X-ray analysis. In the study, building gypsum and metallurgical dust, granulated blast furnace slag, and siltstone mineral modifiers have been used. It has been established that the introduction of modifiers improves the physical and mechanical properties of a binder. This is probably due to the fact that the additives act as crystallization centers during the matrix structure formation and facilitate filling of the stone pore space.

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.

Thermodynamic Foundations for the Use of Gypsum and Magnesia Stone for the Neutralization of Heavy Metal Ions

The need to protect technogenic soils from contamination with heavy metal ions determines the relevance of the topic under study. The aim of the work is to thermodynamically substantiate the ability of gypsum and magnesia stone to neutralize heavy metal ions. Such properties of gypsum and magnesia stone can be called geoecological protection, and the substances themselves can be called mineral geoantidotes. The main method for substantiating geoecological protection properties is a thermodynamic assessment of the reactions of interaction between ions of heavy metals and mineral geoantidotes, as well as an assessment of the solubility product of substances formed during their interaction. As a result of the research, the values of changes in the Gibbs energy during the interaction of mineral geoantidotes and heavy metal ions have been determined; it has been shown that possible products of interaction reactions can be minerals similar to natural ones. Calculations have shown the possibility of reactions occurring under non-standard conditions (1 to 40°C). The experiments carried out made it possible to determine the geoecological protective capacity of gypsum and magnesia stone in non-standard conditions and showed the absence of dependence of the geoecological protective capacity on the ambient temperature in the range from 1 to 40°C. The materials of the article can be useful for the development of technological solutions to reduce harmful pollution by ions of heavy metals of technogenic soils using gypsum and magnesia stone.

Effect of weak inclusions on the fracture toughness of interfaces between various rocks

Fracture toughness (FT) is one of the parameters that characterise the tendency of materials to crack and fracture. FT is usable for individual materials (such as metals, concrete, and composites) and the interfaces between them. The fracture toughnesses of interfaces between different rocks or minerals are also of interest when assessing the stability of rock mass in mining and building construction. The novelty of this work is regarding the fracture toughness of interfaces between various types of rocks. Standardized techniques exist for metals, concrete, and composite materials. For rocks, the investigation uses the methodology recommended by the International Society of Rock Mechanics (ISRM). The paper contains the FT values for gypsum stone, flint, as well as for the interfaces between them, which also include interlayers of carbonaceous clays. The regression equation describes dependence of the fracturetoughness on the relative area of carbonaceous clays interlayers, with the correlation factor R = –0.714.

ПОЛУЧЕНИЕ СМЕШАННЫХ КОМПОЗИЦИОННЫХ ЦЕМЕНТОВ НА ОСНОВЕ ФЕРРИТНОГО КЛИНКЕРА

The possibility of using ferritic clinker as a component of binders with special performance properties is considered. Such types of cements can solve the problems of providing the construction industry with high-strength, resistant to external aggressive effects and relatively cheap binders. However, the mechanism of hardening and curing of cement stone obtained by using ferritic clinkers is complicated and depends on a number of parameters.
 It was found that the greatest thermal effect (more than 70%) during the hydration of the resulting ferritic clinker with the introduction of various additives (lime and gypsum stone) is achieved up to 4 hours from the moment the binder compositions are mixed by means of a calorimetric analysis carried out during the hydration of the developed special binder compositions. That corresponds to the course of the induction period of hydration of the used Portland cement, at the time of the occurrence of primary contacts between crystalline hydrates and sufficient mobility of the cement mass. In this time interval, the strength of the cement stone is not high enough and the produced iron-containing hydration products are able to fill the space of the cement matrix, making it more dense and less defective. 
 The formation of iron-containing crystalline hydrates from ferritic clinker can proceed in several stages: hydrolysis of dicalcium ferrite at the initial stage of the reaction and further interaction of its products with portlandite in the period from 7 to 14 days from the moment of mixing the binder compositions. The main crystalline hydrates formed from ferritic clinker are iron-bearing ettringite and hydrogarnet.
 The study of the physical and mechanical characteristics of cement stone showed that the optimal content of ferritic clinker in the composition of the binder compositions is 5%. With a given quantity, the strength of the cement stone in compression and bending exceeds that of the control sample by 11.5%. The input of 15 and 30% ferritic clinkers into the composition of special binders reduces the strength characteristics by 15-20%.

Influence of the macrostructure on the physic-mechanical and heat-protective characteristics of porous gypsum concrete

The work is devoted to the study of the characteristics of porous gypsum concretes obtained by the methods of foaming and gas formation using an acid blowing agent. Modification of the structure of gypsum stone makes it possible to obtain materials with high strength and good heat and sound insulation characteristics. The characteristics of the durability of the material largely depend on the type of pore structure, and the creation of the required pore structure can be carried out by various methods, among which the most studied and effective are foaming, which involves the introduction of gypsum dough into a pre-prepared foam and gas formation initiated by introducing gas-forming agents into the mixture at the stage mixing. In the work, samples of foam-gypsum and gas-gypsum were made, their strength characteristics and their thermal conductivity were evaluated. Using the method of optical microscopy, a comparative assessment of the macrostructure of cellular gypsum concretes and its comparison with gypsum stone was made. Using an electronic microscope, the microstructures of gas gypsum and foam gypsum were studied at x20, x100 and x500 magnifications. Fundamental differences in the resulting structures are established. From the array of data obtained, the most effective compositions were selected, proving the prospects for the development of porous gypsum materials. Based on the analysis and generalization of the obtained experimental data, recommendations are given on the use of the obtained compositions of porous gypsum concretes in civil engineering.

Technological foundations for solving problem of metallurgy and TPP waste utilization for development of "Green" technology for composite cements production

The chemical-mineralogical compositions and physic-chemical properties of slag waste from the Angren TPP and Uzmetkombinat JSC were determined. A Conclusion was issued on their suitability for use as additives in cement and the possibility of using them for producing new types of hybrid additives for the production of composite Portland cements. With different combinations and ratios of Portland cement clinker, natural gypsum stone, and hybrid additives, the compositions of composite Portland cements were obtained and optimized, and Conclusions were issued on their compliance with the requirements of the Standard of the Republic of Uzbekistan Uz DSt 2830:2014 "Portland cement with composite additives. Specifications".

Influence of dispersion and content of mineral filler on the structure and properties of gypsum binder

The effect of dispersion on the structure and properties of gypsum binder and the content of mineral filler from industrial waste (15%) - crushed steel-smelting slag from the mass of gypsum binder was studied. With the introduction of the optimal amount of filler, in turn, it can significantly improve the macrostructure of the composite, increase the strength of the gypsum stone by 20%, despite the reduction in the consumption of gypsum binder up to 25%. At the same time, their strength characteristics are preserved, relative to the gypsum binder without filler. The resulting gypsum binder can be used in the manufacture of gypsum tongue-and-groove boards for the construction of partitions in rooms with normal humidity.

Protection and Management of the Destroyed Heritage in the Old City of Mosul, Northern Iraq

Mosul has been freed from the clutches of terrorists since 2018, yet the city remains in serious need of reconstruction and redevelopment. The current study attempts to determine whether the fragments of damaged structures can be used in the reconstruction of the old city of Mosul, as well as its economic, cultural, and civilizational feasibility. Old-heritage materials have been categorized into four primary categories, which can be used to avoid confusion while disposing of them. The first category includes antique art elements such as struts, gypsum arches, door frames, and windows, the majority of which were less than 200 years old. The second category included items that were more than 200 years old and were discovered in a few locations, including the Great Mosque of Al-Nuri and the Al-Tahera Church. The third category consists of irregularly shaped stone building materials that were extensively employed in the construction of home walls and ceilings and have survived their engineering characteristics for decades. There are two primary types of stone building materials: limestone and gypsum stone. Finally, plaster, a once-common binder, produced enormous quantities of recyclable materials as well as the new mortar that might be utilized in rebuilding. These significant old-heritage materials went unnoticed and were handled haphazardly. Many of them were removed by massive bulldozers, resulting in the dilemma of their destruction and the search for places to discard them. Recycling these old-heritage materials, according to the study, will help to preserve the irreplaceable artifacts embossed with magnificent ornamentation, sketches, and inscriptions. Obtaining antiquities buried beneath these structures that could be 800 years old or older. Taking advantage of low-cost, high-economic-feasibility building materials and abandoning the idea of destroying and discarding them, which costs a lot of money and pollutes the environment. The geotechnical assessment of categories 1, 3, and 4 revealed that they are recyclable. Category 1 showed that the percentage of damage caused by nature does not exceed 1% and 7% as a result of the war. In categories 3 and 4, the proportion of natural damage caused by weathering does not exceed 1%, while the percentage of natural damage caused by war does not exceed 3%.

Композиционные механоактивированные вяжущие на основе золы тепловой станции, кальцита и двуводного гипса

The paper presents the results of studying the binding properties of a mechanically activated composition including fly ash from the Apatity Thermal Power Plant with increased calcium content, calcite concentrate produced from apatite-carbonatite ores of the Kovdorsky deposit and natural gypsum stone. It was found that the composition, depending on the mixing ratio and curing conditions, displays characteristics of both hydraulic binder similar to lime-ash one and air binder similar to gypsum.

<strong>Comparison of brittleness and flowability between Cipetir Gutta-Percha and commercial Gutta-Percha</strong>

Introduction: Gutta-Percha (GP) is a standard endodontic filling material found in pure form in the Cipetir area, Indonesia. However, a study comparing physical properties (brittleness and flowability) between pure GP and commercially used GP has not been found. Therefore, this study aims to test the brittleness and flowability of Cipetir GP compared to commercial GP. Methods: This study was quasi-experimental. Forty samples were prepared for each material and test, according to ANSI/ADA specification-GP cones-no 78 in 2006. The first step began by making a sample of Cipetir GP using moulds from a cuvette, commercial GP (Inline #80), and gypsum stone. The second step was to test the brittleness (Crease Recovery Tester) and flowability (according to ADA No. 78 of 2000) of Cipetir GP and commercial GP. Results: The brittleness test of Cipetir GP showed unbroken samples, and the commercial GP showed four broken samples. The Fisher's Exact test showed a p-value of 0.087, which means there was no significant difference in brittleness between Cipetir GP and commercial GP. At the same time, the average value of flowability of Cipetir GP and commercial GP were 6.46 mm and 0.19 mm, respectively. The unpaired t-test showed a p-value<0.05, which means there was a significant difference in the flowability between Cipetir GP and commercial GP. Conclusions: There is a brittleness similarity between Cipetir GP and commercial GP, while the flowability value of Cipetir GP is higher than commercial GP. Those initial findings showed that the Cipetir GP might become an excellent candidate to be an alternative endodontic filling.