Mineral Additives Research Articles

Multi-Component Cements for Sealing Casing Columns in Boreholes

Ensuring proper and effective cementing of casing pipe columns in boreholes requires maintaining appropriate technological parameters for the developed slurry recipes. It is also necessary to use technology which guarantees effective displacement of the drilling mud for cement slurry injection into the annular space of the borehole. The most important factors that ensure high efficiency of drilling mud displacement by the cement slurry are, among others, the rheological properties of the liquids involved in the process of cementing the casing columns (drilling mud, cement slurry, buffer liquid). The introduced version of the European cement standard, PN-EN 197-1, includes new types of very economical multi-component cements CEM V/A and CEM V/B, which contain 20–40% Portland clinker with a relatively high content of hydraulic and pozzolanic constituents. They occur in the form of granulated blast furnace slag, natural as well as industrial pozzolans and silica fly ash from the combustion of hard coal. The article presents the results of laboratory tests on the technological parameters of both fresh and hardened cement slurries prepared on the basis of CEM V multi-component cement varieties A and B. These slurries meet the standard technological parameters to a demanding extent, which makes it possible to apply them to cementing columns of casing pipes in deep hole drilling. Their detailed properties can be modified by introducing other mineral additives and chemical admixtures to the cement slurry recipes.

MODIFIED COMPOSITE CEMENTS IN THE SYSTEM СаО–Al2O3–SO3–H2O

Problem statement. One of the most important issues today is the reconstruction, reinforcement of buildings and structures, as well as the creation of new construction materials with the required physical and mechanical properties. The solution to this problem is possible through controlling and regulating the properties of the initial components of the concrete mixture, increasing the amount of surface components at the interface. To control the properties of construction materials, and thus to obtain the cement stone with the specified physical and mechanical properties is possible by means of using various mineral and surface-active additives in the composition of hardened cement stone. Development of sulfoaluminate compositions based on calcium sulfates, alumina cement and surface-active substances (surfactants) makes it possible to significantly expand the raw material base and the scope of application. The purpose of article – obtaining a composite binder with increased density, water resistance and improved technological factors. Conclusions. Alumina cement G-40, 50 and gypsum G-5-II in the ratio of 30−70 % (with hemihydrate gypsum being its main material) have been used in the research to achieve the set purpose. Their properties have been determined as well as the optimal ratio of components for obtaining a specific mineralogical composition with the maximum content of chemically bound water is carried out. Studies have shown that increased content of calcium sulfate has a positive effect on the amount of ettringite and that the optimal value is in the range of 30−40 % by weight of the composition. The exact ratio of components can be determined based on their mineralogical compositions and hydration process conditions. At the ratio of AC-40/G % – 70/30 % a considerable amount of calcium hydroaluminates remain; compressive and flexural strength is 14 and 10 MPa, respectively. When conducting research, the effect of plasticizers on the main technological and physical and mechanical properties of composite binders has been established: the Sika Viscocrete G additive has the greatest plasticizing effect. The composite binders presented above can be used for the manufacture of dangerous structures.

Effect of additions on the self-compacting concrete's absorption

Self-compacting concretes (SCC) are unique concretes that have been developed over the past 30 years. They have the distinct property of being very fluid. Even though they have a great deal of potential for growth, they are still classified as "new concretes" today because of their modest use. SCC differs from conventional vibrated concrete (OVC) in that it is extremely flexible and does not involve the use of vibration. They can be cast in places where there is a high reinforcement density because they compact under the weight of their own mass. In order to reduce the amount of cement caused by the increase in paste volume required to allow the concrete to flow, a large volume of mineral addition is required for the formulation of self-compacting concretes. The main goal of this research was to use the capillary absorption test to determine the impact of various cementitious additions (limestone filler (Lf), brick waste powder (Br), and crushed dune sand (Sd)) by partially substituting a specific amount of Portland cement on the SCC. The findings indicate that, with the exception of brick, all self-compacting concretes produce intriguing results in terms of compressive strength and water absorption.

Вязкость разрушения мелкозернистых бетонов, модифицированных минеральными добавками на основе термоактивированных глинистых и карбонатных пород

The use of modifying additives in cement concrete compositions is the most affordable way to improve their technological, physical, and mechanical properties. However, the high cost and territorial limitation of the most effective modifiers (microsilica, metakaolin) production do not meet the growing customer’s demand. The development of mineral additives based on local raw materials will bridge deficit the most common additives, as well as reduce the consumption of Portland cement. The paper presents the results of determining the fracture toughness (crack growth resistance) of fine-grained concretes obtained from self-compacting concrete mixtures modified with thermally activated clay (Nikitskoye deposit, Saransk, Republic of Mordovia) and thermally activated mixture of clay and limestone (Atemar village, Republic of Mordovia). The paper contains the assessment of crack resistance of fine-grained concretes conducted in accordance with GOST 29167-2021 during equilibrium bending tests of type I samples. The paper found a 9 38% increase in fracture toughness of modified fine-grained concretes with increasing binder consumption due to the introduction of mineral additives in the composition under study

Mineral Additives Based on Industrial Waste for Modifications of Bitumen Polymers

The increase in cost of carbonaceous materials, as well as significant costs of industrial waste, have prompted scientists to use alternative raw materials as components of the construction industry. This study investigated the suitability of waste products from the coke industry as modifying agents for polymer bitumen. The by-product of the coking industry reaches a high level of silicon and is called silicon-containing additive (SCA), the composition of which is similar to the mineral solutions for bitumen. In this article, the results of using SCA as standard additives for modified polyethylene terephthalate (PET) with bitumen waste is presented. Using the Simdist boiling point distribution method, simulated high temperature distillation by gas chromatography, differential thermal (DTA) analyzes, and other methods of physic- chemical properties of bitumen after adding of SCA were studied. It was revealed that the connection and consumption of additives occurs because of the content of aromatic components, as well as an increase in the consumption of bitumen characteristics. Thus, the presented method for obtaining road surfaces based on PET waste and coke production waste meet the requirements of sustainable development, which implements both a significant use of industrial waste as secondary products and their processing into a new product using an energy-saving technology that reduces the consumption of raw materials and resources.

ABOUT THE DEVELOPMENT, APPLICATION AND INNOVATIONS OF POLYMER COMPOSITES

The physical-mechanical, thermophysical, and other important properties of polymer composites primarily depend on the polymer fillers used as modifiers. Examples of fillers include substances that act as structural modifiers, additives, mineral additives, and so on. As studies conducted in this area show, modifiers for various purposes are used to improve chemical and physical-mechanical parameters. The article provides information about the development and production of polymer composite materials. The possibility of obtaining and using composite materials in various fields of technology is shown. In addition, a review of studies that provide a broad understanding of polymer composite materials is also collected. It has been shown that the use of polymer composite materials can lead to significant advances in modern manufacturing. The article also provides information on or-ganic and inorganic fillers with different properties. Based on this, the results of studies carried out in the direction of obtaining polymeric materials using carbon, carbon graphite, fiberglass, etc. are summed up. The nanocomposites of the new generation demonstrate innovative results. This paper shows innovative applications of polymer composite materials for various purposes. All this makes it possible to use the rich mineral resources of Azerbaijan in the production and operation of polymer composite materials

Effect of mineral additions on the mechanical behavior of polymer concretes

PurposeThe objective of this research is to evaluate the influence of mineral additions on the mechanical performances of polymer concrete. This study aims to propose a novel approach formulation of polymer concrete based on reduction in the quantity of the binder and disposal of large quantities of industrial by-products and household waste such as the marble, the brick and silica fume whose valuation in polymer concrete could be an interesting ecological and economical alternative. The incorporation of a rate of 10% brick powder affects the distribution of pores inside polymer concrete, that is, the pore diameters become thinner and decrease and the porosity becomes evenly distributed. The recycled mineral brick powder addition in polymer concrete mix improved the mechanical properties.Design/methodology/approachThis polymer concrete was prepared by using polyester resin and two different types of sand, following a new formulation based on an empirical method. Furthermore, the optimal binder percentage was of 20% resin and a mixture of 52% dune sand and 48% quarry sand according to the Abrams method. To achieve our objective, five rates (from 2% to 10%) of brick powder, marble powder and silica fume were examined. Afterwards, its mechanical characteristics were evaluated via a three-point flexural with compressive resistance. The findings indicated that the addition of brick, marble and silica fume to polymer concrete increases the flexural strength with 21.84%, 12.76% and 9.07%, respectively.FindingsConcerning the compressive strength, the best resistance is that of polymer concretes based on brick powder, and this economic formulation of polymer concrete serves the optimal cost/resistance ratio criteria. It allows an improvement in the mechanical resistance of concrete are obtained by adding brick powder that exceed that of the reference concrete.Originality/valueIn the past few decades, there has been several contribution concerning the subject of the reduction of the binder quantity in polymer concretes and adding the industrial and household wastes. However, previous studies revolving around the same area disregarded the effect of the brick powder, which appears scientifically of great importance for enriching the literature.

Hazardous properties of mineral and organo-mineral plastic additives and management of hazardous plastics

Many plastic additives are mineral or organo-mineral substances having functions as pigments, heat stabilizers, flame retardants, process adjuvants and the like. Are additivated plastics hazardous when they become waste? Data from the Plastic Additives Initiative, a joint industry and EU effort, was used, along with substance hazard statements from the ECHA website and hazard properties from the waste classification. 20 elements of 91 substances, namely Al, B, Ba, Bi, Cd, Co, Cr, Cu, F, I, Li, Mn, Ni, Pb, Pr, Sb, Sn, Ti, V and Zn were selected, and their additives used in 11 polymers, considered. Of the 91 substances selected, 57 are non-hazardous or are hazardous but used at too low concentration to render the plastic hazardous when it becomes waste. 34 substances (= 37% of 91) are hazardous and make plastics hazardous as waste. These are mainly heat stabilizers (for PVC), or pigments and flame retardants (for all polymers). The sorting of these plastics by the mineral concentration of their additives with online XRF is theoretically achievable. With data from previous papers, 63 additives (= 27% of 233) make plastic hazardous. The brominated flame retardants are the less documented. Only essential use should be encouraged for pigments. Waste management today should focus on turning waste into non-waste, not waste leakage. With occupational safety and health regulations during processing, and with product regulations during its second life, the material should be managed as another hazardous or non-hazardous (virgin) raw material, and given end-of-waste status when it enters the loop.

Concrete manufacturing with a low CO2 footprint

The object of the research is the current state of the climate action strategy for cement and concrete production, including possible levers for reducing CO2 emissions. It has been determined that the main source of carbon dioxide emissions per tonne of Portland cement, and subsequently per cubic metre of concrete, is the decarbonization of calcium carbonate, the main raw material component of Portland cement clinker. It also involves the combustion of fossil fuels, which are necessary for the decarbonization and firing of raw materials. Therefore, Portland cement with a reduced content of Portland cement clinker is considered as a solution for concrete manufacturing with a low CO2 footprint. Additionally, the potential of Ukraine in the development of a sustainable Portland cement clinker production approach based on using alternative fuels and alternative raw materials, which will positively affect the total amount of CO2 per ton of clinker, was evaluated. Improved quality performance of cement has been identified as a key direction in product portfolio management to promote cements with a lower clinker factor by increasing the content of active mineral additives. It is shown that the production of concrete with increased strength and durability requirements based on cements saturated with active mineral additives is an important task. Since active mineral additives have different origins, not all of them available for use in cement production exhibit hydraulic properties inherent in Portland cement clinker. Was investigated that «Complex Performance Testing System» (CPTS) as the main test method for evaluating the quality parameters of Portland cement with a reduced clinker factor in accordance with specific applications. This customer-oriented approach opens up the possibility of producing low-CO2 concrete. It has been shown that using the CPTS method, a reduction in the total amount of cement per cubic meter of concrete can be achieved, given the specified parameters of the concrete mix, which has a direct impact on the total amount of CO2/m3.

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.

Managing soil organic carbon in tropical agroecosystems: evidence from four long-term experiments in Kenya

Abstract. In sub-Saharan Africa, maize is one of the most important staple crops, but long-term maize cropping with low external inputs has been associated with the loss of soil fertility. While adding high-quality organic resources combined with mineral fertilizer has been proposed to counteract this fertility loss, the long-term effectiveness and interactions with site properties still require more understanding. This study used repeated measurements over time to assess the effect of different quantities and qualities of organic resource addition combined with mineral nitrogen (N) on the change of soil organic carbon (SOC) contents over time (and SOC stocks in the year 2021) in four ongoing long-term experiments in Kenya. These experiments were established with identical treatments in moist to dry climates, on coarse to clayey soil textures, and have been conducted for at least 16 years. They received organic resources in quantities equivalent to 1.2 and 4 t C ha−1 yr−1 in the form of Tithonia diversifolia (high quality, fast turnover), Calliandra calothyrsus (high quality, intermediate turnover), Zea mays stover (low quality, fast turnover), sawdust (low quality, slow turnover) and local farmyard manure (variable quality, intermediate turnover). Furthermore, the addition of 240 kg N ha−1 yr−1 as mineral N fertilizer or no fertilizer was the split-plot treatment. At all four sites, a loss of SOC was predominantly observed, likely because the sites had been converted to cropland only a few decades before the start of the experiments. Across sites, the average decline of SOC content over 19 years in the 0 to 15 cm topsoil layer ranged from 42 % to 13 % of the initial SOC content for the control and the farmyard manure treatments at 4 t C ha−1 yr−1, respectively. Adding Calliandra or Tithonia at 4 t C ha−1 yr−1 limited the loss of SOC contents to about 24 % of initial SOC, while the addition of sawdust, maize stover (in three of the four sites) and sole mineral N addition showed no significant reduction of SOC loss over the control. Site-specific analyses, however, did show that at the site with the lowest initial SOC content (about 6 g kg−1), the addition of 4 t C ha−1 yr−1 farmyard manure or Calliandra with mineral N led to a gain in SOC contents. The other sites lost SOC in all treatments, albeit at site-specific rates. While subsoil SOC stocks in 2021 were little affected by organic resource additions (no difference in three of the four sites), the topsoil SOC stocks corroborated the results obtained from the SOC content measurements (0–15 cm) over time. The relative annual change of SOC contents showed a higher site specificity in farmyard manure, Calliandra and Tithonia treatments than in the control treatment, suggesting that the drivers of site specificity in SOC buildup (soil mineralogy, soil texture, climate) need to be better understood for effective targeting management of organic resources. Farmyard manure showed the highest potential for reducing SOC losses, but the necessary quantities to build SOC are often not realistic for smallholder farmers in Africa. Therefore, additional agronomic interventions such as intercropping, crop rotations or the cultivation of crops with extended root systems are necessary to maintain or increase SOC.

Performance of resource saving agro-industrial wastes and their utilization in lightweight concrete -A review

The high demand for natural aggregates has created opportunities for the use of agro-industrial waste in the building sector brought on by rising urbanization and the disposal issue of agricultural and industrial waste. Numerous agricultural waste and industrial by-products are already employed in concrete in place of cement, fine aggregate, coarse aggregate and reinforcing elements. Furthermore, there is an increase in the use of Lightweight concrete (LWC) in civil structures such as high-rise buildings, off-shore structures, and long-span bridges owing to the need of concrete, lighter than the conventional one. Presence of natural aggregates makes the concrete dense and heavy, hence the use of lightweight aggregates (LWA), such as perlite, paper industry waste, expanded shale, volcanic pumice, slate, wood ash waste, and expanded polystyrene (EPS), in the production of LWC can effectively decrease the self-weight of a structure. In a comparable manner agricultural wastes, like oil palm shell (OPS), coconut shell (CS), rice husk ash (RHA) and industrial waste like fly ash, plastic aggregate, silica fume (SF), metakaolin (MK) have the potential of a LWA. This study reviewed the utilization of oil palm shells (OPS), coconut shells (CS), expanded polystyrene (EPS), and silica fume (SF) in concrete, among the numerous available agro-industrial wastes. For the past decade, research has been ongoing on aggregate processing to meet special concrete requirements such as low density, thermal insulation, and strength. These wastes exhibit similar properties to conventional concrete when used in combination with mineral additives like SF and RHA, among others. The study also highlights the eco-efficiency and functional benefits of using these wastes as lightweight aggregates (LWA).

Results analysis of building structure inspection operated in corrosion environment

Examination of the reinforced concrete structures state under the influence of organic corrosion environments showed a direct dependence of the nature of the platelet structure of concrete on the polyhydric alcohols adsorption activity of low concentrations. The author has proved the connection between the concrete organic corrosion and its destruction by organic substances, including polyhydric alcohols, aggressive towards cement stone and concrete, especially under the combined action of climatic factors — moistening and drying, freezing and thawing; in these cases, there is an accumulation of internal defects in the concrete in the form of microcracks, which lead to a decrease in its operational properties and further destruction of structures. Field studies conducted by the author included the study of the nature, causes and sources of aggressive secretions, which were monitored, the intensity of the secretions, the limits of distribution and the places of their accumulation were determined. Samples from the damaged areas were taken to clarify the damage nature and degree in the laboratory using physical, mechanical and chemical research methods. According to the inspections results, intensive destruction of the foundation sections under the tanks of finished products, elevated road’s reinforced concrete columns under the alcohol supply pipelines, and floors on acid-resistant tiles were detected. The reasons for the penetration of aggressive solutions through leaks and broken coatings of structures are shown. The inspection also made it possible to identify the causes of aggressive emissions: leakage, insufficient sealing of containers, spills during equipment operation, and others. The author has shown the negative impact of the simultaneous exposure to corrosion environment and low temperatures, and also found that with an increase in the content of mineral additives in the binder, the adsorption of polyhydric alcohols on the cement stone decreases. The high degree of the concrete pore space filling with solutions of polyhydric alcohols is also the main reason for their rapid destruction during frost exposure. Recommendations are given to improve the durability of structures by introducing hydraulic additives into the composition of the binder.

Forecasting Strength Parameters of Hardened Geopolymer Slurries Applied to Seal Casing Columns in Boreholes

Ensuring effective sealing of casing columns in boreholes requires the use of the appropriate technology of cement slurry injection into the annular space and the use of a properly designed cement slurry recipe. Very often, when selecting the technological parameters of the cement slurry, special attention is paid to the technological parameters of the fresh cement slurry, but little attention is paid to the mechanical parameters of the cement sheath that is being formed (the cement slurry after setting). In order to improve the parameters of the hardened cement slurry in the annular space, the cement slurry of a new generation with increased durability (so-called geopolymers) is used. Slurries based on geopolymers are obtained by modifying slurries based on common-use cements with mineral additives with pozzolanic or hydraulic properties. Most often, these additives are fly ashes from the combustion of hard coal or ground granulated blast furnace slags. The article presents the results of testing the mechanical parameters of hardened cement slurries prepared on the basis of CEM V multi-component cement. It was found that the increase in the amount of silica fly ash in the slurry causes a delay in the strength growth rate; such slurries have lower values of early strength. The water–cement coefficient has the strongest influence on the mechanical parameters. The test results are also statistically developed, thanks to which it is possible to select the appropriate mathematical model, and this enables the prediction of mechanical parameters for slurries as a function of their hardening time. Such a mathematical solution can save some labor-intensive research, which, however, cannot be omitted in the final stage of slurry design.

Oxygen uptake rate versus CO2 based respiration rate for assessment of the biological stability of peat, plant fibers and woody materials with high C:N ratio versus composts

The biological stability of organic materials predicts their performance when used as either a soil improver or as an ingredient in growing media. CO2 release in a static measurement and O2 consumption rate (OUR) were compared for seven groups of growing media components. The ratio between CO2 release and OUR was matrix-specific. This ratio was highest for plant fibers high in C:N and with a high risk of N immobilization, intermediate for wood fiber and woody composts, and lowest for peat and other compost types. The effect of variable test conditions in the OUR setup was assessed for plant fibers, where addition of mineral N and/or nitrification inhibitor had no effect on the OUR measurements. Testing at 30 °C instead of 20 °C resulted in higher OUR values as expected, but did not change the effect of mineral N dose. A strong increase in the CO2 flux was measured when plant fibers were mixed with mineral fertilizer; in contrast, addition of mineral N or fertilizer before or during the OUR test had no effect. The present experimental setup did not allow for differentiation between a higher CO2 release as a result of increased microbial respiration after adding mineral N versus an underestimation of stability due to N limitation in the dynamic OUR setup. Results indicate that type of material, C:N ratio and risk of N immobilization all appear to affect the OUR results. The OUR criteria may therefore require clear differentiation based on the different materials used in horticultural substrates.

Prospects of the use of high-tension fiber concrete as the basis for the formation of protective shelters and fortification structures during the russian-ukrainian war

This article analyzes the current state of protective shelters and fortification structures, foresees the modern possibilities of using fastening and basalt-type structures to increase the stability of concrete fortifications both during the construction of buildings for the protection of the civilian population, and for the creation of dugouts, fortifications and fire structures for the protection of personnel in accordance.
 Studies of the physical and mechanical properties of fiber concrete modified with plasticizers and active mineral additives using basalt and polypropylene fibers have shown that their introduction has a positive effect on the strength characteristics of concrete. The compressive strength of fiber concrete at day 28 increases from 61.4 to 77.0 and 96.2 MPa, respectively, and the flexural strength from 7.4 to 12.7 and 13.8 MPa, respectively.
 For the production of reinforced concrete protective materials, it is more effective to create hybrid high-strength concrete using fibers of different nature, followed by the formation of a reinforced concrete slab of the appropriate size. At the same time, the standard provides for the manufacture of prefabricated reinforced concrete elements of fortification structures and platoon support points of wall panels of the SP-1, SP-2 type and floor slabs PP-1 with a thickness of at least 300 mm from heavy concrete of strength class C32/40 with the use of plasticizers and active chemical additives.
 However, when using the obtained hybrid fiber concrete with strength class C50/60 and using a reinforcing mesh according to the calculated data, it is possible to reduce the effective thickness of the fiber concrete slab to 27.5 cm installation of fortification.
 The use of a reinforcing mesh in a complex with basalt fiber provides increased resistance of fiber concrete to the action of a high-speed impact due to an increase in the density of the cementing matrix as a result of a decrease in water consumption, as well as due to spatial three-dimensional reinforcement with dispersed basalt fiber. As a result of the mutual combination of the strength characteristics of the concrete matrix at the micro- and macro-levels in hybrid fiber concrete, it is possible to reduce the thickness of reinforced concrete elements and reduce the weight of the protective structure while meeting the requirements of the standards for such fortifications. An increase in the strength of cement stone occurs due to a decrease in the concentration of stresses in places of local stresses and a redistribution of energy throughout the volume of the material.
 The conducted studies of modern hybrid high-strength concrete with basalt fiber create new opportunities for the creation of protective concrete fortifications and fortification structures.

Characterizations of self-consolidating concrete (SCC) from a physicalmechanical perspective with various additions

Self-consolidating concretes (SCC) are special concretes that have the particularity of being very fluid and have been developed over the past thirty years. They are still qualified today as "new concretes" because their use remains modest, although they have strong development potential. The specificity of SCC compared to ordinary vibrated concrete (OC) lies in the fact that it is extremely fluid and does not require vibration to be implemented. Compacting under the effect of their own weight, they can be poured in areas with a high density of reinforcement. For the formulation of self-consolidating concretes, a large volume of mineral addition is necessary so as to reduce the quantity of cement induced by the increase in the volume of paste necessary to allow the flow of the concrete. The main objective of this work was to determine the effect of different cement additions (Filler limestone (Fc), crushed dune sand (Sd), and silica fume (Fs)) by partial substitution of a certain quantity of Portland cement on the physical-mechanical properties of SCC using the capillary absorption test. The results obtained demonstrate that all self-consolidating concretes give interesting results in terms of compressive strength and water absorption.

Promotion Mechanism of Atrazine Removal from Soil Microbial Fuel Cells by Semiconductor Minerals

In recent years, soil microbial fuel cells (Soil-MFCs) have attracted attention due to their simultaneous electricity production and contaminant removal functions, but soil electron transfer resistance limits their contaminant removal effectiveness. To overcome the above-mentioned drawbacks, in this study, a dual-chamber Soil-MFC was constructed using atrazine (ATR) as the target contaminant, and the electrochemical performance of Soil-MFC and ATR removal were enhanced by semiconductor mineral addition. Analysis of atrazine was performed in soil using HPLC and GC-MS, and analysis of metallic minerals using XPS. Anodic microorganisms were determined using high-throughput sequencing technology. The results showed that the addition of Fe3O4 increased the maximum output voltage of the device by 2.56 times, and the degradation efficiency of atrazine in the soil to 63.35%, while the addition of MnO2 increased the internal resistance of the device and affected the current output, and these changes were closely related to the ion dissolution rate of the semiconductor minerals. In addition, the addition of both minerals significantly increased the relative abundance of both Proteobacteria and Bacteroidota, and Fe3O4 simultaneously promoted the significant enrichment of Firmicutes, indicating that the semiconductor minerals significantly enhanced the enrichment of electroactive microorganisms near the anode. The structural equation modeling indicated that the semiconductor minerals achieved efficient degradation of ATR in the soil through a synergistic mechanism of metal ion leaching and microbial community structure changes. The detection of ATR and its degradation products in soil revealed that the degradation of ATR mainly included: (1) hydrolysis of atrazine by microorganisms to generate dehydroxylated atrazine (HYA); (2) reduced to diethyl atrazine (DEA) and diisopropyl atrazine (DIA) by extracellular electron reduction and re-dechlorination and hydrolysis to HYA. Semiconductor minerals make an important contribution to promoting microbial activity and extracellular electron reduction processes. The results of this study strengthen the power production and ATR removal efficiency of the Soil-MFC system and provide important theoretical support for the on-site removal of organic pollutants and the sustainable application of converting biomass energy into electricity.

Features of the Technology of Ceramics of the Atlym Culture (Based on the Materials of Settlements of Barsova Gora)

Purpose. Barsova Gora is a unique archaeological and landscape site located in the Tyumen Region (West Siberia) of the Russian Federation. A technical and technological analysis of ceramics of the Atlym culture from Barsova Gora I/40 (13 vessels), Barsova Gora I/22a (7 vessels) and Barsova Gora IV/4 (9 vessels) settlements was carried out.Results. It was found that for the pottery manufacture potters of the Atlym culture mainly selected ferruginous clays, varying in the degree of sandiness and the presence of natural inclusions of shells and vegetation fragments. At all sites, potters exploited several clay plots. Recipes and assortment of molding masses vary considerably from settlement to settlement. The most stable technology is typical for ceramics from the site Barsova Gora I/22a for which only one recipe (clay + chamotte) has been fixed. It testifies to homogeneity of pottery traditions that existed on this site. A similar trend is demonstrated by ceramics of the site Barsova Gora I/40, where uncalibrated chamotte was used as the main impurity. The pottery technology of these two sites is very similar, and, apparently, these settlements constituted one group of the Atlym population with similar skills. It is possible that representatives of this group could have participated in the genesis of the Krasnoozerskaya culture of the Ishim River basin, as they recorded significant similarities in the adaptive and constructive skills of pottery making. The opposite situation can be observed at the site of Barsova Gora IV/4, where six single and multi-component compositions have been identified, which indicates a mixture of pottery skills and techniques. Several different groups of potters may have lived at this site, using different assortments of impurities to compose the molding masses. Probably, the Barsova Gora IV/4 site was left by another group of the Atlym population with different pottery skills, which differ from the skills of the “Atlym” from Barsova Gora I/22a and I/40 settlements. It can be assumed that the Atlym population of Barsova Gora IV/4 came to Barsova Gora from other territories, possibly from the Lower Priirtysh.Conclusion. The pottery technology of the sites Barsova Gora I/40 and I/22a has no direct analogues in the previously studied complexes of the Atlym culture in Western Siberia. For the vessels manufacturing technology of the Atlym culture in the territories of the Lower Irtysh River basin, Baraba and the Lower Ob River basin, the dominance of reipes with chamotte is not characteristic. At the same time, the use of chamotte as the main mineral additive and organic solutions is typical for ceramics of the later Krasnoozerskaya culture, which may be based on the Atlym culture. Vessel manufacturing techniques are also similar. Ceramics of the Atlym culture from the Barsova Gora IV/4 site demonstrates the greatest technological similarity with the pottery from The Lower Irtysh River basin. Potters of these territories used a similar range of mineral additives. The surfaces of the vessels were smoothed with a hard, smooth tool. The difference is manifested in the vessels design.

Geochemical characterisation of clastic sediments in Kompina (N'kapa Formation, NW Douala Basin, West Cameroon): Implication for provenance, paleoweathering and sediment maturity

Chemical analyses were carried out on clastic sedimentary rocks in Kompina (N'kapa Formation of the NW, Douala Basin, West Africa) to disclosed the composition of their source rock, characterised their tectonic domains, decipher the intensity of the past weathering, sedimentary cycles and maturity using concentrations of major oxides, REES and trace elements. Provenance diagram constructed from ratios of La/Co, La/Sc, Th/Sc, Cr/Th and from binary diagrams of Zr vs TiO2 and AL2O3vs TiO2, disclosed a felsic rock composition as the source rock of the Kompina clastic rocks. The felsic source rock composition designated for the studied clastic materials is also supported by LREE enrichment over HREE and a negative europium anomaly on chondrite calculation and diagram. New discriminant functions diagrams to delineate between active and passive domains such as DF 1&2(Arc-Rift-Col)M1, DF1&2(Arc-Rift-Col)M2 combined with diagrams of DF(A-P)M, DF(A-P)MT label a passive tectonic setting characteristics for the source rock where there studied clastic materials were sorted. The weathering intensity and plagioclase lixiviation revealed by the CIA and PIA indexes advocate a weak to intense strength of chemical weathering and lixiviation of plagioclase felspars while the CIX and PIX with elimination of CaO in their formulars show extreme intensity of weathering and lixiviation of plagioclase felspars.Most of the samples show immature nature from their ICV values > 1 but with the introduction of ICVnew in this work, where oxides of iron and calcite are considered as cement and eliminated from the formular show that all the studied samples have values < 1 indicating they are mature. Plotted diagrams of Th/Sc, and (Gd/Yb)N ratios, with relationship of Zr and (La/Yb)N shows that the studied clastic materials are mature, second cycle sediments, which have experience zircon mineral addition.