Search Results (213)

This study experimentally investigated the stabilization mechanisms and structure formation models of high-water-content soft soils (>70%) treated with ordinary Portland cement, sulfur aluminate cement, gypsum, and lime. Fifteen single- and composite-stabilizer systems were evaluated using unconfined compressive strength (UCS) tests and microstructural analyses, including SEM, XRD, TG–DTG, and FTIR analyses. The results show that stabilized soils containing cementitious components exhibit significantly higher strength due to the formation of calcium silicate hydrate (C–S–H) gel, which effectively binds soil particles. The addition of sulfur aluminate cement, gypsum, and lime promotes rapid hydration and generates abundant ettringite (AFt) crystals with strong water absorption capacity, contributing to early strength development. Based on these findings, a composite stabilizer (ECS) combining cement with appropriate proportions of sulfur aluminate cement, gypsum, and lime is proposed, achieving substantial improvements in both early and long-term strength. The stabilization process proceeds in two stages: rapid AFt formation absorbs free water and fills large pores to form a three-dimensional network, and then C–S–H gel cementation integrates the soil–AFt framework into a dense and coherent structure. The study provides mechanistic insight and a theoretical basis for stabilizing high-water-content soft soils in coastal and riparian engineering applications. Full article

Vanadium–titanium magnetite is a critical strategic polymetallic mineral resource in China, and blast furnace smelting represents the dominant large-scale industrial process for its utilization. The melting and fluidity properties of titanium-bearing blast furnace slags (TBFS) directly govern stable blast furnace operation and the recovery efficiency of vanadium–titanium resources. This paper systematically reviews research progress on the melting and flow characteristics of TBFS. The influences of main components (TiO₂, CaO/SiO₂, MgO, Al₂O₃), trace oxides, and strongly reduced products TiC and TiN on slag mineral phases, break point temperature (T_Br) and viscosity are summarized. Combined with X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman characterizations and FactSage thermodynamic calculations, the inherent mechanisms are revealed from the perspectives of microstructural network polymerization and crystalline phase precipitation. TiO₂ exerts dual effects: it depolymerizes the silicate network to reduce slag viscosity while promoting the precipitation of high-melting-point perovskite. Al₂O₃ intensifies network polymerization and impairs slag fluidity. MgO, basicity, MnO and BaO can decrease slag viscosity. Solid particles of TiC and TiN generated under the strong reducing atmosphere inside blast furnaces drastically increase slag viscosity and Tbr. This paper proposes that future research should focus on slag systems with higher TiO₂ contents, so as to provide theoretical support for the high-efficiency blast furnace smelting of VTM and resource utilization of titanium-bearing slags. Full article

The interaction of electromagnetic waves with atmospheric aerosols plays a significant role in communication systems and multimedia information transmission. Understanding the interaction of vortex light beams with an aerosol-laden atmosphere is indispensable for establishing a framework of the environmental channel. During the interaction, different optical effects such as absorption and scattering will result in energy attenuation, and this yields the deterioration of the transmission feature of the vortex beam signal. In this study, we present a theoretical analysis of Gaussian vortex beams (GVBs) scattering by diverse aerosol (unformed carbon, dust, sulphate, silicate, soot, and nitrate) particles in the atmosphere on the basis of the well-established generalized Lorenz–Mie theory (GLMT). Combined with the lognormal distribution model for aerosol particles, the attenuation and transmission characteristics of GVBs for different aerosol particles are analyzed. The extinction efficiency $\left(Q_{ext}\right)$ factor of GVB, caused by the absorption and scattering of various aerosols, becomes smaller compared to that of a basic Gaussian beam (GB). Increasing the OAM mode index, the energy attenuation and transmission caused by aerosol absorption and scattering further decrease. Moreover, this research provides a basis to analyze the optical characteristics of the twisted beams in different atmospheric channels, such as wireless communication networks over aerosol-laden systems and material interactions. Full article

The steel industry is currently grappling with the dual environmental challenges of massive steel slag accumulation and carbon emissions. To address the limitations of traditional carbonation processes—namely slow reaction kinetics and insufficient mechanical properties—this study proposes a novel rapid carbonation enhancement method coupling microwave thermal field intensification, silicon carbide (SiC) physical absorption, and potassium silicate chemical activation. The effects of microwave heating parameters on the performance of carbonated steel slag blocks were systematically investigated. The results indicate a significant synergistic effect between the microwave thermal effect and the alkali-activated system. Under the conditions of a 0.14 liquid-to-solid ratio and microwave heating at 90 °C for 45 min, the compressive strength reached a peak of 48.82 MPa (a 44.7% increase over the conventional treatment group). Microstructural characterization revealed the reinforcement mechanism: the introduction of SiC and potassium silicate solution (K₂SiO₃) under microwave heating promotes a denser distribution of carbonation products. Synchronized with alkali activation, this effect promotes the in-situ growth of dense calcite crystals within a gel network, thereby significantly optimizing the pore structure (e.g., reducing the average pore size to 43 nm), and enhancing strength through synergistic effects. This research is subject to further energy and life-cycle assessments, and this approach holds potential for CO₂ mineralization and the recycling of steel slag. Full article

The durability of reinforced concrete is closely related to the transport behavior of water and aggressive ions within the complex nanoporous network of calcium silicate hydrate. While molecular dynamics simulations provide critical atomistic insights into these confined transport behaviors, their immense computational cost limits their scalability to complex structural and temporal domains. To overcome this bottleneck, we propose a novel, modular computational framework that synergizes high-throughput molecular dynamics with advanced graph neural networks. By rigorously learning the mapping between the local atomic environment and kinetic behaviors, our model achieves high-fidelity predictions of pore water diffusion coefficients in saturated calcium silicate hydrate while improving computational efficiency by three orders of magnitude compared to conventional force field methods. Furthermore, the model demonstrates strong transferability and can accurately capture localized nonlinear diffusion characteristics in multiparticle pore structures with rough surfaces. Building on the interchangeability of this framework’s core modules, we envision a visionary multiscale computational strategy that dynamically couples nanoscale atomistic predictions with mesoscale simulations. This work not only provides an ultrafast, highly accurate tool for screening transport properties across diverse structural configurations but also lays the groundwork for next-generation multiscale modeling of chloride ingress, ultimately advancing the design of resilient and sustainable reinforced concrete. Full article

Backfilling the industrial solid waste coal gangue into deep coal mine goafs for CO₂ geological sequestration is a crucial pathway to achieve the synergistic effect of pollution reduction and carbon mitigation. However, in complex deep geological environments, the chemical evolution of multiple mineral phases of coal gangue under gas–water–rock coupling effects and the carbon-controlling mechanism of residual total organic carbon (TOC) remain unclear. In this study, coal gangue from the goaf of the Xiaobaodang Coal Mine was used as the research object. Relying on a customized high-temperature and high-pressure reaction system to simulate the deep in situ environment (45 °C, 10 MPa), and combined with X-ray diffraction (XRD), total organic carbon determination, and isothermal CO₂ adsorption experiments, the geochemical mechanism by which inorganic minerals and organic residual carbon synergistically control the ultimate CO₂ adsorption potential was systematically revealed. The results show that the modification of the CO₂ adsorption potential of coal gangue by gas–water–rock reactions exhibits strong mineral phase differentiation. Systems rich in active silicates generate a large amount of secondary clay minerals through intense carbonation alteration, achieving a significant increase in micro–nano pores and absolute adsorption capacity. Systems rich in carbonates steadily release deep primary adsorption potential by widening mass transfer channels through mineral dissolution. In contrast, systems rich in primary clay minerals face an irreversible attenuation of adsorption space due to physical clogging of pore throats caused by fluid migration. Furthermore, the initial organic carbon content exerts a significant non-linear regulatory effect on the development of the micropore network. The physical adsorption sites provided by the high relative content of layered clay minerals (>41%), coupled with the interfacial enhancement effect exerted by a moderate organic carbon content (0.12~0.16%), constitute an optimal physicochemical synergistic enhancement network, which is the core geological reason for stimulating the ultimate carbon sequestration capacity of coal gangue. The results of this study not only enrich the multiphase interfacial thermodynamic theory of complex heterogeneous geological bodies but also provide solid theoretical support for the precise optimization of target areas and the long-term evaluation of carbon sinks in goaf CO₂ sequestration engineering. Full article

During the continuous casting of high-titanium steel, traditional fluorine-containing mold fluxes are prone to causing fluoride contamination, equipment corrosion, and intensified slag–metal interface reactions. There is an urgent need to develop highly adaptable fluorine-free mold flux systems. In this study, titanium-containing blast furnace slag was used as the primary base material, while borax, soda ash, and witherite were selected as fluoride-substituting mineral raw materials. The effects of these mineral raw materials on the melting properties, crystallization behavior, crystalline phases, and microstructure of fluorine-free mold fluxes were systematically investigated, and an optimized mold flux design suitable for continuous casting of high-titanium steel was further developed. The results indicate that borax significantly reduces the melting temperature and viscosity and markedly suppresses the growth of crystalline phases such as calcium borosilicate, nepheline, and perovskite by weakening the polymerization degree of the silicate network, thereby substantially decreasing the crystallization ability of the mold flux. Soda ash primarily acts as a strong fluxing and network-depolymerizing agent, promoting the formation of low-polymerized structural units. It also enhances the tendency toward ordered atomic arrangement, thereby markedly increasing nepheline precipitation and the overall crystallization ratio. Witherite exerts a relatively mild effect on slag structure and phase evolution; its moderate addition helps synergistically reduce the melting point, viscosity, and crystallization ratio, thereby supporting performance stability. The optimized fluorine-free mold flux, designed on the basis of these findings, maintains a suitable initial crystallization temperature and critical crystallization cooling rate while exhibiting lower melting temperature, viscosity, and crystallization ratio than conventional fluorine-bearing flux. The findings establish a theoretical basis for designing eco-friendly mold fluxes suitable for high-titanium steel and for enhancing billet quality. Full article

This study aims to explore the preparation process and properties of unburned lightweight aggregate using red mud synergistically with fly ash, granulated blast-furnace slag, and other multi-source solid wastes. Curing regimes and alkali-activated systems were controlled. Their effects on physical properties and environmental safety of lightweight aggregate were systematically evaluated. Results show that curing temperature and alkali activator exert significant synergistic effects on physical properties of lightweight aggregates. Steam curing performs better than standard curing. Performance improves with increasing steam temperature. Sodium silicate solution with a modulus of 1.0 is determined as the optimal activator. Under 90 °C steam curing, Sample D2 achieves the best overall performance. Its cylinder compressive strength reaches 6.92 MPa. 1 h water absorption is 14.8%. Softening coefficient is 0.93. Porosity is as low as 31.07%. Microscopic analysis reveals that higher curing temperature significantly accelerates the hydration reaction of the RMLWA system. It promotes the formation of abundant cementitious products such as C-S-H gel. These products fully fill internal pores and microcracks of the aggregate. A dense three-dimensional network skeleton structure is finally formed. For environmental safety, heavy metal leaching concentrations of steam-cured samples are generally lower than those of standard-cured samples. This study realizes high-value resource utilization of industrial solid wastes. It also provides a new technical route for the development of green building lightweight aggregate. Full article

To meet the requirements of forest fire prevention, a water glass-based composite gel foam was developed by introducing hydroxypropyl methylcellulose (HPMC) and nanosilica sol into a sodium silicate/sodium bicarbonate matrix. The resulting water glass/HPMC/silica sol ternary system (SGF-HPMC-SOL) was designed to improve water retention, foam stability, substrate adhesion, and fire-barrier durability. The results indicate that HPMC and silica sol contributed to network reinforcement through hydrogen bonding, polymer-chain entanglement, nanoscale filling, and possible interfacial condensation. The optimized SGF-HPMC-SOL retained 20.4% of its initial mass after heating at 100 °C for 5 h, compared with 4.65% for SGF and 9.54% for SGF-HPMC; reached a carbonization time of 164 s under direct-flame exposure, versus 100 s for SGF and 137 s for SGF-HPMC; and maintained a residual mass of 76% at 800 °C in TGA, compared with 58.3% for SGF and 55.1% for SGF-HPMC. These improvements were associated with the formation of a denser silica-rich protective layer after combustion, which delayed heat transfer to the wood substrate. Under the adopted direct-flame screening conditions, SGF-HPMC-SOL exhibited enhanced flame-retardant performance compared with the reference gel foams, indicating its potential for enhanced flame-retardant performance under laboratory screening conditions for forest fire prevention. Full article

The Judd–Ofelt (J–O) intensity parameters and oscillator strengths are key to understanding the optical transition properties of rare-earth-doped glasses. However, the scarcity of experimental samples and the complex nonlinear relationship between composition and spectral properties pose significant challenges to accurate predictions. To address this, we propose a generalizable framework that integrates conditional generative adversarial network (cGAN)-based data augmentation with an attention-embedded artificial neural network (ANN)–support vector regression (SVR) hybrid model. The cGAN generates physically plausible virtual samples to enrich data distribution and enhance generalization in sparse compositional regions. The attention mechanism in the ANN identifies critical compositional features, which are then leveraged by SVR for robust regression of parameter trends. The framework demonstrates high predictive accuracy for Er³⁺-doped glasses, achieving R² values above 0.93 for Ω₂, Ω₄, and Ω₆, and exhibits strong generalization performance on independent Dy³⁺- and Nd³⁺-doped datasets without task-specific retraining, confirming its practical applicability across multiple rare-earth ions. The model maintains consistency across diverse glass host systems (tellurite, borate, phosphate, silicate/germanate, heavy-metal oxide), and the attention analysis reveals feature importance aligned with established glass chemistry principles. Demonstrated on Er³⁺, Dy³⁺, and Nd³⁺, with potential for a broader range of rare-earth ions through transfer learning and future dataset extensions, this approach offers a data-driven, physics-informed tool for the targeted design of rare-earth optical materials in next-generation optical sensors. Full article

In recent years, there has been an urgent need for integrated solutions to synergistically manage industrial solid waste stockpiling and CO₂ emissions. Single-component solid waste mineralization, such as those using only fly ash (FA) or carbide slag (CS), often encounters performance bottlenecks, typically characterized by a compressive strength of less than 2 MPa and a carbonation efficiency of under 10%. Furthermore, a systematic quantitative understanding of the synergistic interactions within multi-component systems remains absent. This study employs Response Surface Methodology to investigate the interactive effects of solid waste ratios, the water-to-solid ratio, and alkali content, aiming to elucidate the synergistic mineralization mechanism and overcome the bottlenecks of single solid waste mineralization. Under optimized conditions—specifically, 34% CS, 30% phosphogypsum (PG), a water-to-solid ratio of 0.48, and an alkali content of 27%—the system achieved a 7-day compressive strength of 3.5 MPa and a CO₂ mineralization efficiency of approximately 16%, representing a significant improvement over typical single solid waste mineralization materials. Microstructural and spectroscopic analyses indicate that CS serves a dual function as both a calcium source for CaCO₃ precipitation and an alkaline activator for FA. FA constructs a dense aluminosilicate network via pozzolanic reactions, while SO₄²⁻ released from PG promotes the formation of ettringite, facilitating efficient pore filling and early strength development. Additionally, it was observed that surface pores were filled with more products compared to the interior, forming a gradient pore structure that is dense on the outside and sparse on the inside. The AFt and silicate gel were identified as the key microstructural driver for the performance enhancement. This study not only explores the ternary synergistic mechanism of FA, CS, and PG but also provides a viable pathway for developing high-performance solid waste-based mineralization materials that combine mechanical properties with efficient CO₂ sequestration. Full article

This study presents a hierarchical conductive-network strategy to overcome the performance trade-off in cement structural supercapacitors (CSSCs). By incorporating one-dimensional carbon nanotubes (CNTs) and two-dimensional graphene oxide (GO) into Portland cement, we simultaneously enhance its electrochemical and mechanical properties. The approach exploits the complementary roles of the two nanomaterials: CNTs establish a three-dimensional percolation network that facilitates electron transport, while GO promotes formation of a denser calcium silicate hydrate (C-S-H) gel and refines the pore structure by complexing with calcium ions, thereby improving ionic pathways. The k12gc sample attains a specific capacitance of 66.8 F g⁻¹ at 0.1 mA cm⁻², a 58.4% rise in conductivity and a 63% reduction in charge-transfer resistance. At the same time, the composite reduces harmful macropores by 27.9% and strengthens the material, with compressive and flexural strengths increasing by 4.8% and 8.3%, respectively. This work establishes a rational design principle based on functional division between CNTs and GO for developing high-performance, multifunctional CSSCs. Full article

Facing the increasingly severe energy challenges and environmental problems, the development of thermally stable, lightweight, and thermal insulating materials is critical. Herein, we report an organic-inorganic composite strategy combined with a high-temperature carbonization step to fabricate aerogel-containing composites synergistically reinforced with chopped glass fibers and hollow glass microspheres. By systematically varying the ratio of acrylic emulsion to potassium silicate solution, we investigated the effects on the forming behavior, microstructure, hydrophobicity, thermal stability, and thermal insulation performance. Increasing the acrylic emulsion fraction substantially enhanced hydrophobicity, yielding a maximum water contact angle of 129.3°. Concurrently, the apparent density decreased from 0.18 g/cm³ to 0.09 g/cm³ and the thermal conductivity dropped from 57.9 mW/(m·K) to 29.0 mW/(m·K). Mechanical testing revealed that the compressive Young’s modulus decreased with increasing acrylic content, from 3.6 MPa for the purely inorganic sample to 0.55 MPa at 70% acrylic content, reflecting a trade-off between stiffness and organic-derived porosity. Microstructural characterization revealed a hierarchical porous network in which uniformly dispersed hollow glass microspheres and the aerogel-derived silica network form an efficient thermal barrier system. Thermogravimetric analysis demonstrated excellent thermal stability, with total weight loss below 5% up to 800 °C. Infrared thermography analysis showed that, after unilateral heating at 300 °C and 400 °C for 10 min, the backside surface temperature of the composites decreased as the acrylic emulsion content increased. At 300 °C, the temperature decreased from 176.1 °C for AP-1 to 151.0 °C for AP-4, while at 400 °C, it decreased from 228.5 °C to 199.3 °C. These results indicate that the composites exhibit effective thermal insulation and maintain structural stability under high-temperature exposure. Taken together, this facile and scalable approach yields these aerogel-containing composites that combine low density, low thermal conductivity, robust structural integrity, and good environmental resistance, as evidenced by a water contact angle of 129.3°, making them promising candidates for aerospace, building, and industrial high-temperature insulation applications. Full article

Hybrid MTMS–silica aerogels incorporating calcium silicate hydrate (C–S–H), the primary hydration product in cementitious systems, were synthesized via sol–gel processing followed by freeze-drying. The influence of C–S–H loading on pore structure, density, wettability, and thermal transport was investigated. The lowest thermal conductivity (0.068 W/m·K) and tap density (0.30 g/cm³) were obtained at 10% C–S–H loading (wM-CSH10), while the thermal conductivity increases to approximately 0.075–0.082 W/m·K at higher C–S–H content. All samples exhibit mesoporous structures with pore diameters in the range of 10–21 nm. Increasing C–S–H content progressively densified the network, reduced mesopore volume, and enhanced high-temperature mass retention up to 540 °C. FTIR analysis confirmed Si–O–Ca interfacial interactions, while nitrogen adsorption demonstrated persistent mesoporosity across all compositions. Thermal conductivity showed a positive correlation with density, indicating that bulk densification governs heat transport in the hybrid system. Beyond structural modification, the incorporation of C–S–H introduces chemical and microstructural features relevant to cement-based materials, suggesting potential compatibility with cementitious matrices. The results highlight the compositional trade-off between insulation efficiency and structural stability and demonstrate the potential of C–S–H-modified MTMS–silica aerogels for future integration into cement-based composites. These findings provide fundamental insight into their possible use in thermal insulation applications, such as building envelope systems (walls, façades, and roofs used for thermal insulation). Full article

Oil and gas well cement is routinely exposed to aggressive chemical and mechanical environments that can compromise long-term zonal isolation. Conventional Portland cement systems, which rely on hydration products such as calcium silicate hydrate (C–S–H), are particularly vulnerable to acid attack, carbonation, high salinity, and thermal stress. This study investigates a polymer–mineral composite cement in which Class F fly ash is incorporated into an epoxy resin matrix at 0, 25, and 50 weight percent (wt%) loading. The composite samples were exposed for ten days to harsh downhole-representative environments, including hydrochloric acid (HCl, 15–28 wt%), sodium hydroxide (NaOH, 15–28 wt%), sodium chloride (NaCl) brines (20 wt%), crude oil, elevated temperatures up to 100 °C, and high-pressure carbon dioxide (CO₂). Compressive strength was evaluated using a universal testing machine, capturing both deformation strength and ultimate failure strength to assess elastic and structural performance. Across most conditions, the composite maintained strengths exceeding 5000 psi, demonstrating strong chemical resistance. Acidic and CO₂ exposures primarily reduced elastic deformation rather than ultimate strength, suggesting localized interaction with the polymer matrix. Elevated temperature reduced strength to ~2800 psi and diminished elasticity, marking the material’s upper thermal limit. Acetone exposure progressively degraded the polymer network, highlighting potential controlled removability. These findings indicate that embedding industrial fly ash in a polymer matrix produces a mechanically resilient and chemically robust cement alternative with up to 50 wt% industrial waste incorporation. This hybrid system offers a promising approach for wells exposed to acidic, CO₂-rich, or high-salinity environments, where conventional Portland cement may fail. Full article