Enhancement of pozzolanic reactivity of waste autoclaved aerated concrete via CO2 aqueous carbonation: technical and environmental benefits.

Abstract: This study aimed to evaluate the effect of a matrix metalloproteinase inhibitör (Baicalein) on the resin-dentin bond strength in ceramic cementation. The occlusal enamel of sixteen human mandibular wisdom teeth was cut, and glass matrix ceramic (Celtra Duo) overlays were prepared. The samples were randomly divided into four groups. The control group was cemented without pretreatment using total-etch dual-curing resin cement (Variolink N). In the dimethyl sulfoxide and baicalein groups, the solution was applied to the dentin after acid etching. Subsequently, the standard cementation process was continued. In the baicalein and ultrasonic agitation group, unlike the other two groups, after etching, the baicalein solution was applied, ultrasonic agitation was performed for 10 seconds, and agitation was carried out at each stage. The samples underwent thermal aging. Microbars were obtained by cutting the samples, and microtensile tests were conducted. The bond surface and the pretreated occlusal surface were observed using a scanning electron microscope. Shapiro-Wilk test, Kruskal-Wallis test and Dunn's multiple comparison test were applied for statistical analysis. The bond strength values of the control group were significantly higher than those of the other three groups. The use of dimethyl sulfoxide and/or baicalein solutions did not improve the bond strength to the ceramic and dentin for the total-etch dual-cure resin cement.

Abstract Anhydrite is a common type of cement occurring in the tight (low permeability) sandstone reservoirs in continental lake basins. The precipitation of anhydrite cement is governed by fluid activity during diagenesis and its precipitation controls the pore evolution in tight sandstones. It is important to understand the formation mechanism of anhydrite cement in order to forecast the quality of tight sandstone reservoirs ahead of drilling. Jurassic Shishugou Group lacustrine sandstones of the Fukang Sag of Junggar Basin, NW China, are important low‐permeability oil reservoirs. In the Shishugou Group sandstones, abundant anhydrite cement occurring mainly along a deep fault zone is associated with significant oil and gas shows. The electronic probe and laser ablation multi‐collector inductively coupled plasma mass spectrometry (LA‐MC‐ICP‐MS) were applied to investigate the formation time, precipitation conditions, material sources and precipitation process of anhydrite cement and provide new insights for fluid activity, diagenetic system and the formation of pores in the tight sandstone. Anhydrite cement is mainly formed by the dissolution and reprecipitation of early diagenetic calcite cements, feldspars and volcanic rock fragments at the mesodiagenetic stage. The dissolution of calcites and detrital grains (feldspars and volcanic rock fragments) provided sufficient Ca 2+ for both pore‐filling and grain‐replacive anhydrite. Organic acids can provide abundant SO 4 2− from the Permian petroleum source rock and transport it to the Shishugou Group sandstone through the deep‐penetrating faults. The sufficient SO 4 2− in an acidic environment is favourable for the precipitation of anhydrite at the mesodiagenetic stage. The precipitating process of the anhydrite cement in the Shishugou Group sandstone involved obvious mass transfer and dissolution in an open diagenetic system due to the hydrocarbon charging through deep faults.

The paper justifies the prospects for processing low-grade man-made raw materials, represented by waste from the extraction and processing of chalcopyrite ores and mineralized industrial waste water, using methods of extraction, sorption, and cementation of copper and zinc. An overview is given of modern research methods and achievements in the field of hydrometallurgical processing of low-grade raw materials with copper and zinc extraction. The latest developments are discussed in the field of synthesizing selective extracting agents, optimizing technological parameters, and combined technological schemes. Particular attention is paid to the results of experimental tests demonstrating the efficiency of various extraction methods for specific types of raw materials. Modern challenges and prospects for the processing of low-grade and man-made raw materials are identified, in particular, the issue of sulfurous waste liquor disposal. The results of an economic and technological comparison of the extraction method with the conventional sorption and cementation processes are presented, demonstrating its high competitiveness and efficiency of technological application.

Influence of quartz and phosphorus impurities on hydration process and early-age properties of sustainable excess-sulphate phosphogypsum slag cement

Phase composition and structural evolution in water-driven carbonation process of low-calcium Portland cement

The article highlights pressing environmental issues associated with the construction industry, with a particular emphasis on cement production, which is among the most energy-intensive and polluting sectors of all industrial activities. It is noted that cement manufacturing accounts for approximately 8 % of global anthropogenic carbon dioxide (CO₂) emissions, primarily due to the thermal decomposition of carbonates during the production of clinker − the key component of cement. Given the high production volumes and the continuous growth in demand for construction materials, the environmental impact has become persistent and irreversible in the long term. The study investigates the main sources of pollution and proposes strategies for their mitigation. Special attention is given to the search for efficient and environmentally sound technological solutions, including reducing the clinker-to-cement ratio, utilizing alternative binders, and incorporating ecological aggregates into concrete composites. The possibility of using industrial by-products such as slags, fly ash, pozzolans, and other secondary materials is considered, as these can replace conventional components of cement and concrete without compromising technical performance. The purpose of the article. Сomprehensive analysis of the possibilities and prospects for reducing carbon dioxide (CO₂) emissions in the production of cement and concrete composites through the implementation of environmentally sustainable innovative solutions. In particular, the research focuses on assessing the effectiveness of alternative ecological materials used as aggregates in concrete mixtures and evaluating their influence on technological properties. The objective is to identify materials and technologies that not only contribute to a lower carbon footprint but also meet contemporary technical requirements and construction standards. Special consideration is given to the development of practical recommendations for replacing traditional components with more environmentally friendly alternatives, enabling the integration of sustainable development principles into the manufacturing processes of the construction industry. Conclusion. The environmental aspects and technical possibilities of reducing CO2 emissions in the cement and concrete production process through the use of alternative materials and innovative approaches are considered. The main methods of reducing the carbon footprint are reducing the clinker to cement ratio, using alternative binders, and using environmentally friendly aggregates.

Abstract This study presents a life cycle assessment (LCA) of mycocomposite materials, focusing on their carbon footprint and environmental impact, particularly in the substrate preparation and transportation phases. Mycocomposites, created by growing mycelia on organic substrates, offer a promising sustainable alternative to conventional materials. We analyzed two mycocomposites: one grown purely on beech sawdust and the other where 50% of the sawdust was replaced by cardboard separated from plasterboard. Initial results showed that the mycocomposite based on beech sawdust had a lower environmental impact compared to a mixture of sawdust and cardboard. However, this result is probably influenced by the limitations of the LCA model used, which may have inaccurately represented gypsum board as a recyclable material. The model likely used data for standard paperboard, which can be recycled like normal paper, rather than accounting for the specific properties of plasterboard, which is contaminated with gypsum and therefore cannot be conventionally recycled. Although the use of this material is possible, the limited capacity in cement processing and the problems in recycling plasterboard cartons in the closed cycle of gypsum board production indicate that in the near future there will be a need to process this material and its use as biomass for mycocomposite materials seems more than promising. The results highlight the importance of refining LCA models to better reflect material-specific properties when assessing the environmental performance of innovative materials such as mycocomposites.

Dispersion is a common phenomenon in miscible displacement flows. In the primary cementing process displacement takes place in a narrow eccentric annulus. Both turbulent Taylor dispersion and laminar advective dispersion occur, depending on flow regime. Since dispersion can cause mixing and contamination close to the displacement front, it is essential to understand and quantify. The usual modelling approach is a form of Hele-Shaw model in which quantities are averaged across the narrow annular gap: a so-called two-dimensional narrow gap (2DGA) model. Zhang & Frigaard ( J. Fluid Mech ., vol. 947, 2022, A732), introduced a dispersive two-dimensional gap-averaged (D2DGA) model for displacement of two Newtonian fluids, by modifying the earlier 2DGA model. This brings a significant improvement in revealing physical phenomena observed experimentally and in three-dimensional computations, but is limited to Newtonian fluids. In this study we adapt the D2DGA model approach for two Herschel–Bulkley fluids. We first obtain weak velocity solutions using the augmented Lagrangian method, while keeping the same two-layer flow assumption as the Newtonian D2DGA model. These solutions are then used to define closure relationships that are needed to compute the dispersive two-dimensional flows. Results reveal that the modified version of the D2DGA model can now predict expected frontal behaviours for two Herschel–Bulkley fluids, revealing dispersion, frontal shock, spike and static wall layer solutions. We then explore the displacement behaviour in more detail by investigating the impact of rheological properties and buoyancy on the mobility of fluids in a planar frontal displacement flow and their vulnerability to fingering-type instabilities. As the underlying flows are dispersive, our analysis reveals three distinct behaviours: (i) stable, (ii) partial penetration of the dispersing front, and (iii) unstable regimes. We explore these regimes and how they are affected by the two fluid rheologies.

By employing thin section analysis, scanning electron microscopy (SEM), homogenization temperatures of fluid inclusions, and carbon–oxygen isotope analysis of carbonate cements, this study conducted a temporal-quantitative investigation into the porosity evolution of relatively high-quality reservoirs in the Second Member of the Xujiahe Formation (Xu-2 Member) in the Xinchang area of western Sichuan. The analysis focused on quantifying porosity loss due to compaction, cementation, and porosity enhancement from dissolution. Results indicate that compaction exerted the most significant impact on reservoir quality in the Xu-2 Member, causing over 70% of total porosity loss. Cementation processes, including carbonate cements, silica cements, and authigenic chlorite, further degraded reservoir properties. Authigenic chlorite precipitated earliest at burial depths of 600–800 m, while authigenic quartz and carbonate cements persistently affected the reservoir at depths of 2000–5000 m, reducing porosity by at least 10% (up to 21%). Dissolution processes initiated at approximately 3500 m burial depth, generating secondary porosity of ≥2%, with a maximum increase of 16%. Integrating these findings with the natural gas accumulation history, the coupling relationship between pore evolution and gas accumulation was elucidated. The study reveals that reservoir tightness in the Xu-2 Member developed at burial depths of 4050–5300 m, with large-scale gas accumulation predominantly occurring prior to reservoir densification. The findings provide critical guidance for identifying high-quality tight sandstone reservoirs and optimizing exploration targets in the Xu-2 Member of the Xinchang area, Western Sichuan Basin, thereby supporting efficient development of regional tight gas resources.

The cement process is a crucial operation in the drilling of oil and gas wells, in which errors would be extremely costly and time-consuming to rectify. Some of the technical parameters that influence this process include the pH of water used in the preparation of the cement slurry. This study investigates the impact of water pH on the properties of Class-G cement slurry. The cement slurries have been mixed using distilled water and four water samples at pH 9.5, 10, 11, and 12, respectively, with no additives. Iraqi and UAE cements' physical and chemical analyses were performed according to API standard specifications. The findings indicate that UAE cement largely meets the API specifications. However, Iraqi cement has some deviations due to a difference in manufacturing processes, which caused failures when the tests were conducted with fresh water. The findings of three physical tests demonstrated that mixing cement with alkaline water (pH>7) has a negative effect on the cement physical properties, especially compressive strength and density. On the other hand, the thickening time test for two kinds of cement demonstrated that when the pH level increases, it contributes to a delay in the thickening time of roughly 50 minutes for both types. This study considers pH effects in the preparation of cement slurries to ensure that bonding was not impaired and exclude post-operational failures.

Influence of nano-SiO2 and nano-TiO2 on early hydration process of cement: Hydration rate, hydration products microstructure, calcium ion solubility, and diffusion ability

Evolution characteristics and possible sources of acoustic emission during the damage process of Cement Improved Aeolian Sand

In recent decades, replacing clinker in cement with mineral additives has become increasingly common, and the range of such additives continues to expand. An example is the growing number of cement types defined in European standards. Some of these standards allow the use of fine recycled concrete waste as an active additive in amounts up to 35%.. Finely ground waste glass, whose quantity steadily increases worldwide, can also be classified as an active additive. Due to its relatively high silica content, finely ground waste glass is a potential supplementary cementitious material. However, the high alkali content in glass limits its use in cementitious products to 5–10% of the binder mass. Considering that silicate binders (water glass) with high alkali activity are also used in construction and influence the hydration process of cement, it can be assumed that waste glass likewise has a significant impact on the properties of cement composites, particularly on hardening parameters and the development of mechanical strength. However, scientific literature lacks data on the synergistic effect of alkaline components of finely ground waste glass and water glass on the cement hydration process, its hardening, and the strength of cement products. Therefore, this study aimed to analyze the mechanism of the influence of a glass-based composite, consisting of waste glass additives and water glass, on the physicochemical and mechanical properties of cement composites.

This study evaluates cementation gap, cement volume, and porosity levels in three-dimensional crown restorations using four permanent resin materials and printers, and examines changes after thermomechanical ageing. In the study, phantom models prepared on the maxillary first premolar were used, and the digital scanning, CAD design, 3D printing, cementation, and ageing processes were carried out according to standard protocols. The samples were divided into four groups based on the permanent resin material used: Group C (Methacrylate-based resin), Group S (UDMA-based composite), Group P (Bis-GMA/TEGDMA-based), and Group V (Bis-EMA/UDMA-based). All samples were designed with a 50μm virtual cementation gap and evaluated by micro-CT before and after ageing. The findings showed statistically significant differences between the groups in terms of cementation gap and porosity volume (p < 0.001). The lowest void volume and porosity were measured in the group C, while the highest values were observed in the group S. No significant difference was observed between the groups in terms of total cement volume. Additionally, a strong positive correlation was found between cement volume and porosity. The obtained data reveal that the resin material used and the production process play a decisive role in the internal compatibility of restorations. Thermomechanical ageing, on the other hand, caused significant changes, particularly in structural properties. These results indicate that permanent resin restorations produced by 3D printing should be evaluated for their clinical viability considering cement gap and porosity behavior. This study has revealed that the cementation gap and porosity levels of permanent resin crowns produced with a 3D printer vary significantly depending on the type of material used and the production process. Therefore, in clinical applications, not only aesthetic and mechanical properties but also cementation compatibility and microstructural properties should be taken into consideration.

The rate of Cu2+ cementation on a Zn cylindrical sheet lining the inner wall of a cylindrical batch-stirred reactor was studied, where a U-shaped wiper consisting of two plastic-coated steel rods was used to agitate the solution. The novelty of the reactor lies in the integration of a rotating U-shaped wiper that provides simultaneous mechanical surface renewal and bulk agitation, enhancing copper removal efficiency without the need for additional stirring mechanisms. Variables studied were wiper rotational speed, wiper diameter, pH of the solution, and the initial concentration of CuSO4 solution. The results revealed that the rate of cementation was unaffected by pH, however, it was increased by increasing other variables. Under optimized operational conditions, the wiper-assisted cementation process achieves nearly complete removal of Cu2+ ions from solution within 10 min. Mechanical power consumption measurements indicated that the reactor is energy efficient when the cell is agitated using a large-diameter wiper that rotates at relatively low speeds.

Abstract To understand the influence of Mo, Si, and Ti during aluminizing pack cementation processes of Mo-Si-Ti alloys, two ternary Mo-Si-Ti alloys (eutectic Mo-20.0Si-52.8Ti and eutectoid Mo-21.0Si-34.0Ti) were investigated and compared with pure Ti and Mo-40Ti (all in at.%). The coating formation mechanisms, phase composition, and microstructures of the different substrates were compared. Subsequently, the effect of the different elements on the oxidation behavior was evaluated, using thermogravimetric analysis at $${700}\,^{\circ }\text {C}$$ 700 ∘ C and $${900}\,^{\circ }\text {C}$$ 900 ∘ C for 100 h in synthetic air. In addition, the type I ( $${900}\,^{\circ }\text {C}$$ 900 ∘ C ) and type II ( $${700}\,^{\circ }\text {C}$$ 700 ∘ C ) hot corrosion behavior of the Al-coated Mo-Si-Ti alloys was investigated for 24 h and 100 h in synthetic air + 0.1% SO $$_2$$ 2 . While the initial Al-rich coating phase was consumed or transformed at $${700}\,^{\circ }\text {C}$$ 700 ∘ C , it successfully facilitated the formation of a protective Al $$_2$$ 2 O $$_3$$ 3 scale on the surface, even if the underlying reservoir was diminished. At $${900}\,^{\circ }\text {C}$$ 900 ∘ C , the Al coatings on both substrates failed, and a hot corrosion-induced pesting dominated. While Si generally has a positive effect on oxidation and hot corrosion resistance, the main impact of Mo is dictated by its evaporation, and Ti can lead to the formation of TiO $$_2$$ 2 as a mixed oxide with Al $$_2$$ 2 O $$_3$$ 3 .

Interfacial kinetics regulation and electrochemical optimization in ultrasonic-induced sponge cadmium nucleation

Argentinean loessial soils are the main deposits of this kind of soil in South America, and cover an area of more than 600,000 km2. They are eolic soils that can preserve their original structure generated when they were deposited (primary loess) or being transported or altered in place (secondary loess or loessoid). Recent deposits are mainly primary, ML and CL-ML, whereas the older ones are similar to other unsaturated clayed and silty soils, CL and CH. Geotechnical behavior varies from collapsing soils, for primary loess, to overconsolidated by desiccation for the secondary loessoid deposits. Advances have been made in the knowledge of the cementation processes, the dielectric properties and the mechanical variations with different levels of strains, in the use of new nondestructive methods, in-situ tests and spatial variations of the most significant parameters. It has been progressed in the modeling of foundations and different infiltration processes. The engineering design is conditioned by the type of collapsibility. The criteria used in constructions try to annul the entrance of water into the ground; to eliminate the collapsibility by means of the improvement of its unstable structure or to avoid using direct foundations. In hydraulic works predominates the use of the hydro-compaction combined with methods to accelerate the collapse. Loessic soils are apt for using in embankments and fillings, because compaction destroys their macroporous structure and they behave like other types of silty soils. In order to clarify the engineering problems and its solution two history cases are explained.

In order to elucidate the high-temperature reaction process of solid waste-based high belite sulphoaluminate cement containing residual gypsum in clinker (NHBSAC) and obtain the formation laws of each mineral in clinker, this article studied its high-temperature reaction kinetics. Through QXRD analysis and numerical fitting methods, the formation of C4A3S¯, β-C2S, and CaSO4 in clinker under different calcination systems was quantitatively characterized, the corresponding high-temperature reaction kinetics models were established, and the reaction activation energies of each mineral were obtained. The results indicate that the content of C4A3S¯ and β-C2S increases with the prolongation of holding time and the increase in calcination temperature, while CaSO4 is continuously consumed. Under the control mechanism of solid-state reaction, the formation and consumption of minerals follow the kinetic equation. C4A3S¯ and β-C2S satisfy the D4 equation under diffusion mechanism control, and CaSO4 satisfies the R3 equation under interface chemical reaction mechanism control. The activation energy required for mineral formation varies with different temperature ranges. The activation energies required to form C4A3S¯ at 1200-1225 °C, 1225-1275 °C, and 1275-1300 °C are 166.28 kJ/mol, 83.14 kJ/mol, and 36.58 kJ/mol, respectively. The activation energies required to form β-C2S at 1200-1225 °C and 1225-1300 °C are 374.13 kJ/mol and 66.51 kJ/mol, respectively. This study is beneficial for achieving flexible control of the mineral composition of NHBSAC clinker, providing a theoretical basis and practical experience for the preparation of low-carbon cement and the optimization design of its mineral composition.