Properties Of Slag Research Articles

Semi-dry and aqueous carbonation of steel slag: Characteristics and properties of steel slag as supplementary cementitious materials

Accelerated carbonation of steel slag presents a viable method for CO2 sequestration and the valorized utilization of steel slag. This study aimed to investigate the impact of semi-dry and aqueous carbonation, as well as the carbonation degree, on the microstructure and properties of steel slag. Additionally, it evaluated the feasibility of utilizing carbonated steel slag as supplementary cementitious materials (SCMs). Steel slag was subjected to CO2 (20% volume percentage) at 2 bar pressure for both semi-dry and aqueous carbonation process at room temperature with water/solid ratio of 0.08 and 5, respectively. The carbonation duration was varied (10 min, 30 min, 60 min, and 120 min) to adjust the degree of carbonation. Mortars and pastes with 30 wt% carbonated steel slag were formulated and their compressive strength and volume expansion values were quantified. The findings revealed that the CO2 uptake values for steel slag after 2 hours of semi-dry and aqueous carbonation were only 3.75% and 1.50%, respectively. Compounds such as Ca(OH)2, Mg(OH)2, and Ca2SiO5 demonstrated high carbonation reactivity during the semi-dry carbonation process, whereas Ca(OH)2 and Mg(OH)2 exhibited only a marginal increase in aqueous carbonated steel slag. The specific surface area of steel slag increased with an increase in the carbonation degree, attributed to the formation of silica gel or amorphous C-S-H during carbonation. However, the hydration activity of carbonated steel slag diminished with an increased degree of carbonation due to the consumption of alkaline minerals. Conversely, pozzolanic activity was enhanced with a higher degree of carbonation, owing to the formation of silica gel. The cumulative heat release of cement containing SDC30 (semi-dry carbonation for 30 min) within 24 h and 72 hours showed increases of 16.0% and 3.5%, respectively, aligning with the compressive strength results. Semi-dry carbonation treatment significantly enhanced the early-stage cementitious properties of steel slag/cement composites. Specifically, the 3-day compressive strength of mortar containing 30 wt% SDC30 increased by 22.7% relative to the reference mortar, composed of 30 wt% uncarbonated steel slag and 70 wt% Portland cement. Carbonation markedly improved the volumetric stability of steel slag with the extent of improvement was positively correlated with the carbonation degree for both semi-dry and aqueous carbonated steel slag. Aqueous carbonation was more effective in promoting the hydration process of free CaO and MgO more effectively than semi-dry carbonation.

Assessment of the physicochemical properties of alkali-activated slag blended with belite-rich cement subjected to carbonation attack

The present study investigated the physicochemical transformation of alkali-activated slag (AAS) under CO2 exposure. The belite-rich cement (BRC) used as an additive up to 30 wt% of GGBFS and Ca(OH)2 was used for alkali activation. The threshold ratio of lime/slag and BRC/binder was 4.5% and 20%, respectively, for the improvement in strength and the physicochemical properties. The residual strength after CO2 exposure was higher for an AAS mix prepared with 30% BRC/binder and a 6% lime/slag ratio. Due to the additive (BRC) in AAS, the unreacted β-C2S and portlandite act as a buffer during CO2 exposure. The additional supply of Ca2+ ions provided via Ca(OH)2 contributed to promoting the reactivity of AAS. The decrease in critical pore diameter by 51.6% as the prepared AAS with the higher BRC/binder ratio was exposed to CO2 increased the solid-phase assemblage per unit volume, which also contributed to the physicochemical properties.

Effect of magnetized water on alkali-activated slag mortars incorporating raw and calcined marble powder

This study investigates the impact of magnetized water (MW) on the fresh and hardened properties of alkali-activated slag (AAS) mortars incorporating raw marble powder (RMP) and calcined marble powder (CMP). In the initial stage of the study, control specimens were manufactured to ascertain the optimal parameters for molarity, curing temperature, and curing time. The optimal parameters were determined based on the highest strength results: a molarity of 10, curing time of 24 hours, and curing temperature of 110 ℃. In the second stage of the study, while maintaining these optimal parameters, RMP and CMP were substituted in place of blast furnace slag (BFS) at rates of 10%, 20%, 30%, and 40%. In this study stage, tap water (TW) and MW were employed as the mixing water. A mini-slump test was conducted to assess the fresh state properties of the prepared AAS mortars. Subsequently, ultrasonic pulse velocity (Upv), flexural strength (ff), and compressive strength (fc) tests were carried out to evaluate the hardened state properties of the specimens. Finally, scanning electron microscopy (SEM) analysis was performed to examine microstructural properties. According to the results, the ff and fc values of the mortars produced with CMP substitution using TW showed an increase of up to 20.6% compared to the mortars based on RMP and produced withTW. Additionally, utilizing MW as the mixing water enhanced the workability of AAS mortars. Consequently, incorporating CMP and MW in AAS mortars further improved fresh and hardened state properties compared to RMP and TW.

Microstructures and properties of alkali-activated slags with composite activator: Effects of Na2O equivalents

Cementitious materials composed entirely of solid waste are expected to replace cement and alleviate environmental pollution problems. Due to limitations in reaction rate and strength, a composite activator comprising NaOH and water glass was employed to investigate the effect of composite activator content (0–12.0% Na2O equivalent) on pore solution pH, hydration products, microscopic morphology, and pore structure of ternary alkali-activated materials prepared by blast furnace slag, desulfurization gypsum and carbide slag. Additionally, the microstructure development results were corroborated through characterization of fluidity, setting time and compressive strength. Results indicate that the reaction process of alkali-activated material accelerates as Na2O equivalent increases from 0 to 8.0%, thereby promoting calcium aluminum silicate gel and hydrotalcite formation, and facilitating the continuous filling of pores, which leads to a dense structure formation. However, excessive gel products are generated on bonded particle surface when Na2O equivalent exceeds 8.0%, hindering polymerization process; meanwhile, the presence of microcracks leads to an increase in macropores (≥10 mm3) proportion resulting in a decrease in compressive strength. Notably, the increase in Na2O equivalent gradually suppresses ettringite formation. Life cycle assessment demonstrates that the preparation of mortar is more environmentally sustainable. Based on the optimal compressive strength, the reduction in global warming, abiotic resource depletion, acidification, and eutrophication potential of mortar compared with cement is 78.7%, 39.7%, 17.9% and 29.2%, respectively. This work contributes to further improving the resource utilization of solid waste, and extending the application of conventional solid waste cementitious materials in the domain of emergency repair engineering.

Hydration behavior and cementitious properties of steel slag: From an early age to a long-term

In China, steel slag as a solid waste caused land occupation and environmental pollution, and its utilization ratio is relatively low. To increase the utilization field and ratio of steel slag, hydration behavior and cementitious properties of three types of steel slag were investigated and compared based on test results from an early age to a long-term via multiple techniques. Experimental results suggested that steel slag showed a strong latent hydraulic activity at a later age, and the mechanical strength of steel slag paste specimens (w/b=0.3) could reach 15 MPa at 360 days. Cementitious properties of steel slag were primally depended on the hydration of calcium silicate (C3S and C2S), calcium aluminate (ferrite), glassy phase in steel slag, especially for calcium silicate. The sum amount of calcium silicate in used steel slag was approximately from 21% to 28%, and the amount of C2S was significantly greater than that of C3S. The hydration of C2S and glassy phase resulted in the continuous increase in bound water content of steel slag, and a certain content of C2S still existed in pastes at 360 days. The mechanical strength of steel slag pastes markedly increased at a later age due to more hydrates formed in the microstructure.

Analyzing the Mechanical and Durability Characteristics of Steel Slag-Infused Asphalt Concrete in Roadway Construction

Steel slag is a solid byproduct of the steelmaking process, widely generated in the metallurgical industry. Due to its alkaline nature and excellent adhesive properties with asphalt, it represents a potential road construction material with outstanding road performance, making it well-suited for utilization in highway construction. This paper conducts a systematic analysis of the physical and chemical properties of steel slag, specifically South Steel Electric Furnace slag, and compares it with natural basalt and limestone aggregates. The aim is to establish a foundation for the application of steel slag in asphalt mixtures. Building upon this foundation, we carry out proportioning design for AC-13C and SMA-13 steel slag asphalt mixtures, followed by a comprehensive study of their high-temperature stability, low-temperature stability, water stability, and fatigue performance. Our research reveals variations in the chemical composition of different steel slags, with CaO, SiO2, and Fe2O3 being the primary components. The content of harmful elements varies depending on the steelmaking raw materials and additives used. Notably, the optimum asphalt-to-aggregate ratios for AC-13C and SMA-13 significantly surpass the specified requirements. The freeze–thaw splitting strength ratio and residual stability of steel slag AC-13C and SMA-13 asphalt mixtures exceed the specified requirements, with AC-13C demonstrating the highest water stability, boasting a freeze–thaw splitting strength ratio of 94.07%, and a residual stability of 93.8%. In terms of fatigue characteristics, SMA-13 exhibits a longer fatigue life than AC-13C, indicating superior fatigue performance for steel slag SMA-13. Steel slag enhances the abrasion resistance and rutting resistance of asphalt pavement surface layers, fully meeting the performance requirements for high-grade road surface layers.

Developments in Atomistic and Nano Structure Evolution Mechanisms of Molten Slag Using Atomistic Simulation Methods.

Molten slag has different properties depending on its composition. The relationship between its composition, structure, and properties has been the focus of attention in industrial manufacturing processes. This review describes the atomistic scale mechanisms by which oxides of different compositions affect the properties and structure of slag, and depicts the current state of research in the atomic simulation of molten slag. At present, the research on the macroscopic properties of molten slag mainly focuses on viscosity, free-running temperature, melting point, and desulphurization capacity. Regulating the composition has become the most direct and effective way to control slag properties. Analysis of the microevolution mechanism is the fundamental way to grasp the macroscopic properties. The microstructural evolution mechanism, especially at the atomic and nanoscale of molten slag, is reviewed from three aspects: basic oxides, acidic oxides, and amphoteric oxides. The evolution of macroscopic properties is analyzed in depth through the evolution of the atomic structure. Resolution of the macroscopic properties of molten slag by the atomic structure plays a crucial role in the development of fundamental theories of physicochemistry.

Self-sensing properties of cementless ultra-high performance concrete (UHPC) with slag aggregates

This research addresses the environmental impact of traditional cement-based construction materials and explores sustainable alternatives. The study aims to explore the mechanical properties, flowability, setting time, and self-sensing performance of cementless ultra-high performance concrete (UHPC) by utilizing the electrical properties of electric arc furnace slag (EAF slag) as a replacement for natural aggregates, along with alkali-activated slag as the binding material. Comparative analyses are conducted between cementless UHPC with EAF slag and silica sands, as well as the impact of incorporating carbon fiber. The study reveals that cementless UHPC with EAF slag exhibits improved fluidity and slightly increased setting time compared to UHPC with silica sands, attributed to the spherical shape and ball bearing effect of EAF slag. While the compressive and tensile strength of cementless UHPC with EAF slag is slightly lower than that of UHPC with silica sands, it still meets UHPC standards with strengths of 150 MPa and 8 MPa, respectively. Nonlinear curve fitting accurately quantifies the self-sensing performance, yielding precise simulation results. Importantly, EAF slag-based UHPC exhibits superior self-sensing capabilities, outperforming carbon fiber incorporation. Unlike UHPC with silica sands, which generates substantial noise even with carbon fiber, EAF slag-based UHPC demonstrates effective self-sensing with minimal noise, even in the absence of carbon fiber. This study expands the understanding of self-sensing performance in cementless UHPC by effectively utilizing EAF slag as a replacement for natural aggregates. The results suggest that the valorization of EAF slag has the potential to enhance sustainability and the self-sensing capabilities of cementless UHPC.

Influence of Nano-Fly Ash on mechanical properties, microstructure characteristics and sustainability analysis of Alkali Activated Concrete

Ordinary Portland Cement (OPC) composites significantly affect the atmosphere by emitting Carbon dioxide (CO2) during its production process. The addition of Nano Materials (NM) for the construction could change the matrix configuration at the nano level. Compared to other NMs, converting industrial by-products and locally available materials into nano size can enhance the characteristics of the binder composites. This research work focuses on the effects of Nano Fly ash (nFA), on the fresh, mechanical, microstructural, and thermal resistance properties of Fly Ash (FA) and Ground Granulated Blast Furnace Slag (GGBFS) based Alkaline Activator Nano Concrete (AANC). The impact of adding nFA in various concentrations of 3 %, 6 %, 9 %, 12 %, and 15 % on the properties of AANC was studied. By adding nFA in an optimal proportion, the degree of geo-polymerization is improved which is found by Field Emission Scanning Electron Microscopy (FESEM), X-ray diffraction (XRD), Thermogravimetric analysis (TGA), Energy Dispersive X-Ray Analysis (EDAX) and Fourier Transform Infrared (FTIR). Results indicate that the addition of nFA significantly increased polymerization, reducing initial and final setting times by 13.3 %–52.5 % and 5.3 %–28.8 %, respectively. Moreover, nFA promoted the formation of polymer gel, leading to a denser microstructure with fewer cracks and refined pores, resulting in a substantial increase in mechanical strength, particularly with 9% nFA, achieving an optimal CS of 56.14 MPa after 28 days which is 37.97 % improvement compared to the mix without nFA. However, when nFA was added, beyond 9 %, the performances declined due to its high surface area resulting in a non-uniform dispersion that promoted agglomeration. This dispersion enhances the formation of C-A-S-H and C–S–H gels. The addition of nFA in AANC can be an environmentally friendly solution by reducing CO2 emissions, energy consumption, cost reduction and increased sustainability.

SLAG—software for reconstruction of historical smelting processes based on slag properties

AbstractThe publication presents the functions of the SLAG software created to recreate historical metallurgical processes. SLAG allows for determining the smelting temperature, the viscosity of the metallurgical melt, and the oxygen and sulfur fugacities during smelting. With software, both liquidus temperature and melt viscosity can be calculated using different models, covering the range of chemical compositions of historical slags as wide as possible. Based on thermodynamic calculations, SLAG allows the performance of O2 and S2 fugacity calculations in the temperature range of 1000–2000 K (727–1727°C). The range of applicability of other properties (viscosity and liquidus temperature) depends only on the limitations of individual models. Using SLAG, it is also possible to create predominance area diagrams (PADs) and diagrams that consider the viscosity's dependence on temperature for slag of a given chemical composition. Based on glass transition temperature (Tg) and melt fragility, it is also possible to reconstruct the conditions that prevailed during the various stages of historical glass manufacturing processes.

Investigation of the engineering and environmental properties of cement mortars incorporating ladle furnace steel slag

While the use of ladle steel slag in concrete offers several potential advantages, there are significant research gaps that need to be addressed to promote its safe and effective utilization in the construction industry, e.g. the variations in slag properties, such as chemical composition and physical characteristics, can influence concrete performance. Moreover, even there is some research on the mechanical properties of concrete containing ladle steel slag, more in-depth studies are needed to assess the long-term durability of such concrete and the research should focus more on evaluating the environmental impact of using ladle steel slag in concrete. The paper reports the fundamental findings of a research study focused on the treatment of ladle slag to be applied as a cement substitute in the manufacturing of cement products. The research aimed to determine the optimal proportion of admixture based on treated ladle slag and evaluate the environmental properties of the resulting cement composites. The treatment process involved mechanical activation, specifically grinding the ladle slag fraction of 0/8 mm using a vibrating mill (Coarse slag) and a ball mill (Fine slag). The treated ladle slag, as an admixture, was examined in conjunction with four types of cement (CEM I, CEM II, CEM III, and CEM V). The research findings revealed that the incorporation of coarse ladle slag enhanced the workability of fresh cement paste across all tested formulations. Moreover, the utilization of treated ladle slag as an admixture in cement paste (substituting cement) exhibited a retarding effect on the setting time. As the age of the test specimens progressed (90 to180 days), the strength properties of the samples with ladle slag admixture approached those of the cement composites prepared using natural aggregates. The climate change impact of cement mortars per strength unit spanned from 0.82 to 2.75 kg CO2eq/MPa for composites incorporating finely-ground slag, and from 0.9 to 3.1 kg CO2eq/MPa for composites utilizing coarse slag. The grinding of ladle slag, even up to 30 wt% cement replacement, did not significantly impact the overall global warming potential and climate change, considering the average mill energy consumption of 50 kWh per 1 t of material.

Indirect solution modeling of melting behavior of SiO2 based on the image processing technology

AbstractThe utilization of tempered blast‐furnace slag through the direct fiber forming process to produce high‐value thermal insulation materials offers a dual benefit: it efficiently utilizes the latent heat in the unused slag and significantly increases the value of blast‐furnace slag utilization. However, measuring the melting properties of iron slag at high temperatures is challenging. In this study, the melting behavior of SiO2 in a high‐temperature molten pool was investigated. We employ dynamic visual data (video stream) captured via a non‐contact charge coupled device video recording system to extract SiO2 contours through image processing. The change in image centroid characteristics is used to establish a convolution function relationship, and MATLAB's traversal search algorithm determines the centroid position of SiO2. Given that SiO2 is proportionate to crucible pixels, the area of the SiO2 is calculated through pixel statistics within these contours. A new indirect method is then proposed to process image information to obtain SiO2 volume and mass at different time points. An exponential fitting yields the melting rate function of SiO2. Finally, this indirect method has been compared with shape from shading, quantitative characterization, and dimensional analysis techniques. Besides, the strengths and limitations of each method have been discussed. Our findings reveal that the indirect solution method presented here boasts straightforward calculation steps and imposes minimal image format requirements, which provides theoretical and technical support for the direct fiber forming process of blast‐furnace slag.

Investigation on the compressive strength and durability properties of alkali-activated slag mortar: Effect of superabsorbent polymer dosage and water content

This paper presents the properties of alkali-activated slag (AAS) mortar additivated with a superabsorbent polymer (SAP) to improve its mechanical and durability properties. The effect of different dosages of SAP (0.0–0.3% with respect to the blast furnace slag weight) and different extra water additions on setting time, autogenous shrinkage, compressive strength, water permeability, frost resistance, heat of hydration, and porosity is presented and discussed. The results highlight the beneficial effect of adding SAP on the mechanical and durability properties of the proposed mixtures. Only at higher percentages of SAP and additional water occur performance drops due to excessive macro-porosity of the system. It is interesting to point out that, in contrast, shrinkage always decreases as the percentages of SAP addition and additional water increase, although it cannot be completely eliminated. Experimental evidence also highlights that significant benefits can be gained from using this material in harsh environments.

Overview of the role of fluorine in the mold fluxes

Fluoride is one of components of the traditional mold flux, but it causes environmental pollution. With the increasing requirement of environmental protection on the metallurgical industry, it is a trend to develop low fluorine or fluorine-free mold fluxes in the future. In recent years, many scholars have researched some low fluorine or fluorine-free mold fluxes. However, because the action mechanism of fluorine in mold flux is not completely clear, the performance of mold fluxes composed of fluorine-substituting components has not reached the effect of fluorine-containing mold fluxes. In view of this, this paper summarizes the effects of fluorine in protective slag from macro and micro aspects: in the study of the macro properties of mold flux, it is generally believed that a certain amount of fluorine plays an important role in adjusting the melting temperature, viscosity and surface tension of mold flux, but its adjusting mechanism is not clear; in terms of microstructure, the structural behavior of fluorine in mold flux is very complicated due to the influence of alkalinity, other components and fluorine content. The microstructure of slag determines the properties of slag. Therefore, the complexity of the structural behavior of fluorine leads to the complexity of the transformation mechanism of the physical properties of mold flux, which makes it impossible to control the properties of mold flux fundamentally and increases the difficulty in selecting the alternative component of fluorine in the process of developing low fluorine or fluorine-free mold flux. Therefore, it is necessary to further study the influence mechanism of fluorine on the structure of mold flux.

Захиснівластивостішлакопемзобетону та шлакобетону по відношенню до сталевої арматури

Захиснівластивостішлакопемзобетону та шлакобетону по відношенню до сталевої арматури

Optimization of Ball Milling Parameters for Efficient Copper Slag Valorization

The ball milling process increasingly employed in a symbiotic materials recovery context is associated with high environmental footprint due to its energy-intensive nature. The current paper addresses this issue by optimizing the milling of copper slag, recognized as a promising alternative resource within the construction sector. The slag was milled in a stirred mill using stainless-steel (SS), carbon-steel, and yttria-stabilized zirconia (YSZ) balls with(out) grinding aid (GA). The milling time and energy, besides milled slag properties, were monitored. Performance variations of different milling balls were explained through the impact theory. Results show that efficient size reduction happens in the first hours regardless of the ball material and diameter. In a specific surface area (SSA) between 3600-3800cm2/g (d50=11µm), substituting SS with YSZ balls decreased milling time and energy by ∼50%, comparable to processes performed with GA. The addition of smaller balls (Ø6.3mm) to bigger balls (Ø9.5mm) caused energy consumption to decrease starting from SSA=3200±100cm2/g and cumulative particle size to slightly reduce. The effect of the ball-to-slag ratio on the milling efficiency was found stronger than the ball diameter change. A strong influence of the parameter optimization on the ball milling efficiency was proposed, potentially benefiting powder production industries.

Drying shrinkage properties of fiber-reinforced alkali-activated slag and their correlations with microstructure

The superior strength, durability, and environmental sustainability of alkali-activated slag (AAS) systems renders it a viable alternative to those based on Portland Cement (PC). However, drying shrinkage in AAS systems is a highly complex process requiring extensive testing. Several studies have reported the incorporation of fibers to AAS systems as an effective way not only to enhance its strength but also to reduce its drying shrinkage, but the information is scattered. In pursuance of this objective, the present study investigates the impact of incorporating steel, polypropylene, polyvinyl alcohol and glass fibers at varying volume fractions from 0.1% to 0.3% on both mortar and concrete AAS specimens. According to the findings, incorporating fibers to AAS concrete increased its compressive strength by up to 13% when compared to the plain mix. A higher volume fraction of 0.3% for steel and glass fiber inclusions significantly minimized the drying shrinkage of AAS concrete by 27% and 31%, respectively. However, due to the increased heterogeneity and subsequent void formation in fiber-reinforced AAS systems, it was noted that the mass loss resulting from the loss of moisture is greater in these cases. Despite the greater mass loss at earlier ages, the fibers in AAS specimens demonstrated their ability to restrain the shrinkage strains. The microstructural studies, which distinctly depict the morphology of AAS paste and the interaction between the fibers and matrix, further validate these conclusions.

Contribution to a better understanding of long-term hydration, structuration and mechanical properties of slag based cementitious materials: Experimental and modeling approaches

Blast Furnace Slag (BFS), a by-product of the steelmaking process, can be used as a mineral addition in blended cement. In addition to reduce CO2 emissions in the construction field, the use of BFS in cementitious materials also contributes to the improvement of their mechanical and durability properties. However, despite the numerous studies proposed in the literature about the hydration properties of BFS-blended cement, some aspects remain unclear, such as the influence of slag substitution rate on hydration kinetics and on the stoichiometry of hydrates formed and their impacts on both microstructural and mechanical properties. For these reasons, the present study aims firstly to better understand how BFS-blended cement hydrates based on a complete hydration model that considers both kinetics and chemical reactions. The only required input data are the formulation parameters (i.e. water-to-binder ratio (W/B), substitution rate of clinker by slag (fs)), and curing. This study does not introduce the heat of hydration, which limits the validity of other existing models to short-term hydration. Analytical laws involving calibration parameters, which are assumed to vary with the substitution rate of clinker by slag, represent the hydration kinetics of clinker and slag while a stoichiometric approach is adopted to describe the chemical formation of hydrates. In order to calibrate and validate the parameters involved in the hydration model, four different cement paste mixes formulated with 0%, 30%, 50%, and 80% (by mass) of slag are studied in terms of hydration degrees and microstructure evolutions, and completed with data from the literature. The amounts of hydrated phases and those of dry densities, particularly at later ages, are well reproduced by the hydration model. Porous structure evolutions are also investigated in terms of partition between capillary and CSH gel pores by comparing the capillary porosity predicted by the model with the total porosity measured experimentally. Finally, predictive modeling of mechanical properties (compressive strength and Young modulus) of tested materials are finally proposed based on hydration model outputs. A good agreement between experimental and predicted data is observed.

Мониторинг загрязнения почвенного покрова нефтепродуктами и разработка способа его рекультивации

Introduction. Oil waste has a high degree of toxicity and poses a great danger to humans and to the natural environment as a whole. One of the most acute problems is the negative impact of oily waste. The negative impact of petroleum products on the soil can lead to irreversible changes in the chemical composition, physical biochemical and microbiological properties of the soil, which determine, among other things, its fertility. The main potential sources of soil pollution with oil and petroleum products include ground vehicles, oil storage facilities, oil refining enterprises, as well as transport transporting petroleum products. The study of the physico-chemical properties of ash and slag waste to reduce the anthropogenic load on the environment. In Kazakhstan, as a result of the production activities of a number of large oil-producing enterprises, huge amounts of oil-and-oil soils have accumulated, significantly polluting the environment. The areas of polluted lands continue to increase as a result of emergency oil spills. Therefore, on the territory of the Kumkol oil field, it is very relevant to conduct environmental monitoring of soil pollution and carry out reclamation measures to restore land fertility The purpose of the research. Environmental monitoring in the conditions of development of the Kumkol deposit and the development of an effective technology for the reclamation of contaminated lands through the use of highly effective biological products to reduce the anthropogenic load on the natural environment. Research materials. For the research, samples of smeared soils of various sites of the Kumkol deposit of the Kyzylorda region of Kazakhstan were used. Research methods. The choice of soil monitoring methods was carried out taking into account the available sources of pollution and types of soil pollution: chemical, biochemical, biochemical, microbiological, etc. The analysis of existing methods of ecological monitoring of soils shows that due to the high cost and technological complexity, the use of a number of them is limited. Therefore, an effective approach to determine the degree of contamination of soils with petroleum products is the use of bioindication and biotesting methods Research results and discussion. As a result of the environmental monitoring, the technology of recultivation of polluted lands was developed using a biological product obtained by composting rice husks with the help of aerobic and anaerobic soil microorganisms. The scientific novelty of the proposed method of recultivation of contaminated soils is confirmed by the patent of the Republic of Kazakhstan, which confirms the scientific and practical significance of the work. The results of the research can be useful in the reclamation of oil-contaminated lands in other regions and the restoration of their vegetation cover. Conclusion. The monitoring of soil pollution by oil and petroleum products shows that the main potential sources include ground transportation facilities, oil storage facilities, oil refineries and transport, which first brings petroleum products. The developed technology of biorecultivation, firstly, reduces the anthropogenic load on the soil surface due to the biodegradation of oil spills, and, secondly, at the same time, the disposal of spilled oil in the form of vermicompost is carried out. In the work, for the first time on the basis of the application of a new technology for the reclamation of contaminated land resources using a biological product obtained from waste of plant and food origin, a new approach to the problem of utilization of oil-contaminated soils and restoration of their fertility, with the production of vermicompost, is proposed. Suggestions for practical application. A new approach to the problem of utilization of oil-contaminated soils and restoration of their fertility, with the production of vermicompost, is proposed, which can be useful in solving environmental problems in other oil-producing regions of Kazakhstan.

Effect of two different crystal forms of alumina on hydration properties and mechanical properties of steel slag−cement composite cementitious materials

ABSTRACT In the present work, two common nano-alumina (NA) with different crystal forms (α-NA and γ-NA) are used to research the effects of steel slag−cement composite cementitious materials, which include the hydration properties and mechanical properties. The results show that the NA can enhance the strength of steel slag−cement composite cementitious materials, especially the early strength. Meanwhile, when the addition amount of γ-NA was 1%, the maximum compressive strength and flexural strength at 28 d were 35.43 and 5.21 MPa, respectively; when the addition amount of α-NA was 3%, the maximum compressive strength and flexural strength at 28 d were 36.27 and 4.89 MPa, respectively. In addition, according to the analysis of X-ray diffractometer and differential thermal analysis, it was concluded that the effects of the two types of alumina on the strength were mainly pozzolanic effect and filling effect. The pozzolanic effect of γ-NA was significantly stronger than that of α-NA. However, the large surface area of γ-NA affected the dispersion of the particles and the filling effect. According to scanning electron microscope analysis, compared with α-NA, γ-NA had significantly more hydration products and tighter adhesion. In conclusion, the addition of NA not only improved the properties but further realized the value-added utilization of steel slag.