Titanium gypsum (TMG) is an industrial by-product generated during the chloride-process production of titanium dioxide (TiO2). Its large output combined with low utilization has led to significant environmental concerns. In this study, high-aspect-ratio calcium sulfate hemihydrate whiskers (CSHW) were synthesized from TMG by a hydrothermal method using lanthanum ions (La3+) and dodecyltrimethylammonium chloride (DTAC) as synergistic modifiers. To the best of our knowledge, this work presents the first systematic comparison of the action mechanisms of La3+ and DTAC as modifiers for TMG-based calcium sulfate hemihydrate whiskers. The mechanism of anisotropic growth regulation was also investigated. X-ray diffraction (XRD) and thermogravimetric (TG)-differential thermogravimetric (DTG) analyses confirmed that all products were alpha-CaSO4.0.5 H2O. The introduction of La3+ and DTAC did not alter the crystal structure or thermal stability, suggesting that modification primarily occurred through surface adsorption. Zeta potential, contact angle, Fourier-transform infrared (FTIR) spectroscopy, energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) analyses showed that La3 + and the quaternary ammonium group of DTAC preferentially adsorbed on the negatively charged lateral facets. This increased the surface potential and hydrophobicity, enhancing interfacial stability. Scanning electron microscopy (SEM) results revealed that the modifiers were enriched on the (200), (110), and (110) facets, suppressing radial growth while promoting elongation along the c-axis. Under the optimal conditions (2.0 wt% La3+ and 0.25 wt% DTAC), the whiskers achieved a maximum aspect ratio of 98.57, which was approximately 186.62% higher than that of the control sample. Density functional theory (DFT) calculations confirmed stronger co-adsorption on the lateral facets, particularly the (200) facet, where orbital hybridization between La 5d, N 2p, and O 2p stabilized the lateral facets and promoted growth along the c-axis. The present work provides a feasible strategy for preparing high-aspect-ratio CSHW from TMG and further clarifies the crystal growth mechanism governed by the synergistic interaction between inorganic salts and surfactants.

To clarify the potential of High Ferrite Cement (HFC) in seawater concrete, this work systematically investigates the chloride binding mechanisms of ferrite phases with different Al/Fe ratios. Density Functional Theory (DFT) and Ab Initio Molecular Dynamics (AIMD) showed that, in pure water, the increase of Al content induces the adsorption energy of C6AF2 and C4AF on Ca/Fe sites to decrease by 2.92eV and 3.77eV, respectively. This weakens Ca-O and Fe-O bonding and thereby facilitating the dissociation of [Ca-O7], [Fe-O4] and [Fe-O6] polyhedra. Notably, when chloride salts are used as the mixing water, such an inductive effect becomes even more pronounced. Experimental results show that the maximum hydration exothermic rates of C6AF2/DI and C4AF/DI enhanced by 105.0% and 275.3% respectively (compared with C2F/DI). The average elastic modulus of C3(A,F)H6 elevated by 131.1% compared with C4FH13. An increased Al/Fe ratio significantly enhanced the hydration activity and micromechanical properties of the ferrite phase, with its morphology evolving from gel and sheet to polyhedral form.C2F showed the strongest chloride binding capacity (Friedel’s salt weight loss peak: 11.50%). A higher Al/Fe ratio favors the formation of C3(A, F)H6 over Friedel’s salt, while reducing cumulative pore volume and densifying the structure.

To reduce carbon emissions in the cement industry and improve high-magnesium limestone utilization, this study investigated the phase evolution and carbonation hardening performance of a high-magnesium low-calcium binder (HM-LCB) prepared by calcining high-magnesium limestone (HML) and sandstone (SS) at temperatures from 900 degrees C to 1300 degrees C. Results revealed that (3-C2S was predominantly formed at 900-1100 degrees C via solid-state reactions, whereas temperatures exceeding 1200 degrees C induced the progressive phase transition from (3-C2S to akermanite (Ca2Mg-Si2O7) and merwinite (Ca3MgSi2O8), culminating in complete conversion at 1300 degrees C. MgO effectively suppressed the transformation of C2S to C3S2, incorporated partially into the (3-C2S structure as a solid solution, and functioned as a mineralizer that promoted liquid-phase sintering. Samples calcined at 900-1100 degrees C were rich in f-CaO and exhibited high CO2 sequestration capacity. The 1200 degrees C sample exhibited optimal carbonation performance, with compressive and flexural strengths of 114.6 MPa and 16.9 MPa, attributed to a dense microstructure and polymerized silica gel. Carbonation products shifted from calcite-dominated compositions (900-1200 degrees C) to Mg-calcite and aragonite-rich assemblages (1300 degrees C). Mg2+ incorporation promoted polymorphic transformation of calcium carbonate, resulting in a greater increase in flexural strength. This study provides valuable insights for the high-value utilization of high-magnesium limestone and offers guidance for optimizing calcination processes to develop sustainable construction materials with reduced carbon footprint.

The cement industry accounts for approximately 7-8 % of global anthropogenic CO2 emissions, necessitating the urgent development of low-carbon cementitious alternatives that incorporate industrial solid wastes. In this study, high-ferrite Portland cement (HFPC) clinkers were synthesized by co-calcining steel slag (SS) and limestone powder (LSP) at varying mass ratios (LSP: 30-55 wt%). The effects of LSP dosage and calcination temperature on mineral phase formation, microstructural evolution, hydration behavior, and mechanical performance were systematically investigated using X-ray diffraction (XRD), quantitative Rietveld refinement (QXRD), scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), backscattered electron imaging (BSE), thermogravimetric analysis (TG-DTG), Fourier-transform infrared spectroscopy (FT-IR), mercury intrusion porosimetry (MIP), and isothermal calorimetry. Results demonstrate that increasing LSP content progressively drove mineral phase reconstruction from a C2S-C4AFC3MS2 assemblage toward a C3S-dominant system. HFPC-40 (40 wt% LSP, calcined at 1300 degrees C) achieved the highest C4AF content (25.19 wt%) and exhibited a unique two-stage hydration mechanism: rapid early-age C4AF hydration generating ettringite (AFt) and alumino-ferrite hydrate (A(F)H3) gel, followed by progressive C2S hydration producing C-S-H and Ca(OH)2 at later ages. HFPC-50 attained the highest 28-day compressive strength of 75.40 MPa, while excessive free CaO in HFPC-55 induced early cracking. MIP analysis confirmed that later-stage silicate hydration densified the microstructure, reducing porosity from 34 to 50 % at 3 days to approximately 19-21 % at 90 days across the HFPC-40, -45, and -50 compositions. This work provides mechanistic insights into waste-derived high-ferrite clinker systems and offers a technically viable, environmentally favorable pathway for large-scale steel slag valorization.

The different industrial solid wastes exhibit significant differences in carbonation activity and cementitious properties due to variations in their mineral composition. This study investigates the differences and potential mechanisms in the degree of carbonation (DOC) and cementitious properties among the main mineral phases (3-C2S and y-C2S in industrial solid waste through experimental and theoretical simulations. The results demonstrate that y-C2S exhibits excellent DOC (34.8 %) compared to (3-C2S (26.7 %), yet its compressive strength (68.0 MPa) is substantially lower than to (3-C2S (105.9 MPa). Firstly, the nucleation mechanism of the C2S carbonation reaction was investigated using ab initio molecular dynamics (AIMD). It revealed that HCO3- is an indispensable intermediate state during carbonation, and the dissolution of Ca2+ critically influences the polymerization degree. Combined with density functional theory (DFT) results, the larger Ca2+ dissolution displacement in (3-C2S facilitates partial migration of Ca2+ in pores, where they precipitate as CaCO3 and effectively fill the pores, which enhances the cementitious performance of (3-C2S. In addition, the excellent DOC of y-C2S is attributed to its greater solubility with Ca2+ and lower adsorption energy, more negative bond difference, and more charge transfer with H2CO3. This study provides theoretical support for polycrystalline collaborative preparation and performance prediction of C2S.

In this study, a physical foaming technique was integrated with carbonation curing to prepare lightweight porous cement-based carbon-sequestering composites (LPCC). Portland cement (P.I 42.5) was used as the binder, with an animal protein foaming agent modified by sodium dodecyl sulfate (SDS), sodium α-olefin sulfonate (AOS), and hydroxypropyl methylcellulose (HPMC) to enhance foaming capacity and foam stability. Specimens with foam volume fractions of 0%, 30%, 50%, and 70% (F-0 to F-70) were cast and subjected to accelerated carbonation under 99.9% CO2 at 0.1 MPa for 24 h. The effects of foam dosage on compressive strength, water absorption, dry density, and carbonation behavior were systematically investigated, with phase and microstructural evolution characterized by XRD, TG-DTG, FT-IR, SEM, and LF-NMR. Results show that increasing foam dosage progressively increases total porosity and average pore diameter, forming abundant interconnected macro-pores that serve as three-dimensional CO2 diffusion channels. At 70% foam dosage, compressive strength decreased to 0.6 MPa and water absorption reached 64.88%, while carbon fixation attained a maximum of 24.7 wt%, a fourfold enhancement over the control. This work demonstrates a synergistic optimization of carbon sequestration efficiency and lightweight performance, providing a viable technical pathway for low-carbon innovation in construction materials.

The massive accumulation of fluorogypsum poses severe environmental challenges, rendering the development of sustainable resource utilization strategies imperative. This research explores the effect of carbide slag (CCS) on the physical properties and hydration behavior of a new fluorogypsum-based multi-solid waste cementitious materials (FBCM). FBCM is composed of high-volume fluorogypsum (FG), fly ash (FA), and ground granulated blast-furnace slag (GGBS), with a minor dosage of Portland cement. The underlying hydration behavior was elucidated via multiple characterization methods, including isothermal calorimetry, TG, SEM, and pore structure analysis. The results demonstrate that as the CCS dosage increases, the mechanical properties of the materials exhibit an initial enhancement followed by a subsequent decline. The optimal overall performance is achieved at a CCS dosage of 2.0 wt%, yielding a 28 days compressive strength of 37.5 MPa and a softening coefficient of 0.97. Microstructural analysis reveals that CCS provides a suitable alkaline environment, where the released OH⁻ ions effectively accelerate the depolymerization of reactive silica and alumina from the solid waste precursors. Subsequently, these released ionic species promptly combine with calcium and sulfate ions within the system, significantly fostering the formation of ettringite (AFt) and C-(A)-S-H gels, which eventually construct a dense microstructural framework. Furthermore, FBCM effectively immobilizes fluoride ions and significantly mitigates leaching risks, providing a viable and practical solution for the large-scale, safe valorization of industrial solid wastes.

Structural batteries can simultaneously achieve the integration of both mechanical loading and electrochemical energy storage within a single material system. Owing to their abundant raw material resources, low cost, and promising ion transport properties, cement-based batteries with porous cement matrix serving as a reservoir for the electrolyte have recently attracted significant attention. However, there is a key challenge that the cementbased electrolyte is difficult to simultaneously achieve high ionic conductivity and cycling stability while maintaining adequate mechanical strength. In this work, a porous semi-solid electrolyte has been fabricated through a NaCl-templating and carbonation strategy. The NaCl sacrificial template creates an interconnected pore network that enhances electrolyte infiltration and ion transport while preserving mechanical robustness. The optimized electrolyte with a NaCl/gamma-C2S ratio of 1 exhibits a compressive strength of 15.44 MPa and an ionic conductivity of 22.47 mS & sdot;cm- 1. By coupling a NiFe cathode and a Zn anode, the assembled structural batteries operate stably within 1.5-2.0 V, achieving a maximum specific capacitance of 17.03 mAh & sdot;g- 1 at 1 A & sdot;g- 1 with an energy density of 7.82 Wh & sdot;kg- 1 at a power density of 124.5 W & sdot;kg- 1. These results demonstrate the feasibility of carbon-negative porous electrolytes for integrating mechanical and electrochemical functionalities in sustainable structural energy storage systems.

Magnesium slag (MS) carbonation offers significant potential for CO2 sequestration and sustainable cement production, yet conventional wet carbonation suffers from limited efficiency due to surface passivation. This study investigates the synergistic effects of wet grinding carbonation coupled with sodium citrate (SC) addition on MS carbonation performance. Various conditions were evaluated, including magnetic stirring (M-0), colloid mill grinding (C-0), and grinding with SC dosages (C-0.4, C-1, C-3). The optimal condition (C-0.4) achieved CO2 uptake of 40.29 % and carbonation degree of 79.21 %. Compared with traditional wet carbonation, the carbonation degree is increased by 89.14 %. Wet grinding effectively removes surface carbonate layers while optimal SC dosage (0.4 wt%) promotes calcium carbonate formation. The microstructural analysis demonstrated particle size reduction (D50 from 19.60 to 4.68 mu m) and increased specific surface area (6.92 x 10-2 to 25.48 m2/ g). When applied as cement replacement, carbonated MS (C-0.4) exhibited superior performance. With 10 % replacement, the 28-day compressive strength exceeded that of ordinary Portland cement by 6.91 MPa. The enhanced performance is attributed to pore filling and additional C-S-H gel formation. This work provides insights into coupling mechanisms of mechanical activation and chemical enhancement for efficient mineral carbonation, offering a promising pathway for industrial waste valorization.

The wastewater containing Cu2* produced by the electroplating industry brought environmental pollution risks. The existing treatment methods, such as chemical precipitation and adsorption, face problems in efficiency, economy, and secondary pollution. Removing Cu2* economically and efficiently has become a hot topic. This study develops a three-electrode cell employing self-fabricated reticulated vitreous carbon (RVC) as the cathode to electrochemically reduce and remove Cu2* from wastewater. By integrating systematic parameter optimization, catalyst screening, kinetic modeling, and density-functional-theory calculations, we elucidated the reaction mechanism and the governing kinetics of Cu2* removal from Wastewater. The RVC-based electrochemical cell achieved a Cu2* removal rate of 91.31 % under the optimized conditions of 0.50 V vs. SCE, 60 min, 40 degrees C, and pH 3.0. Electroplating a catalytic layer onto the electrode markedly boosts the copper-removal efficiency. Among the three catalysts (Fe, Cd, Mn), the initial removal rate of the Fe catalyst can reach 93.00 %. Fe catalyst exhibits both faster electron transfer and a much stronger Cu2*-binding energy (-5.19 eV) than RVC (-3.18 eV), Cd (-1.84 eV), or Mn (-1.37 eV). The method maintains high efficiency for high-concentration Cu2* wastewater: even at 1,000 mu g mL-1, the Cu2+ removal rate is >= 93.00 %. This research provides an economically feasible technical solution for efficiently removing Cu2* from wastewater, with both environmental and economic benefits.

The substantial accumulation of industrial by-product gypsum, primarily from China's power generation, phosphate fertilizer, and fluorine chemistry sectors, poses a significant environmental challenge. To address this issue and valorize the waste, this study provides, to the best of our knowledge, the first systematic mechanistic comparison of successfully synthesized high-aspect-ratio calcium sulfate hemihydrate whiskers (CSHW) from titanium gypsum (TMG) via a hydrothermal method, using dodecyltrimethylammonium chloride (DTAC) or tetramethylammonium chloride (TMAC) as crystal modifiers. The adsorption behaviors and underlying growth mechanisms were systematically investigated through integrated experimental and theoretical approaches. Optimal aspect ratios were achieved at 0.50 wt% DTAC and 0.75 wt% TMAC, corresponding to significant enhancements of 107.2 % (reaching 71.24) and 48.9 % (reaching 51.19), respectively. Mechanistic analyses revealed that the (CH3)3N+ groups of both surfactants chemically adsorb onto the side facets, inhibiting radial growth and promoting axial elongation. Crucially, DTAC, with its dodecyl chain, forms hemi-micellar or bilayer adsorption structures-a capability lacking in TMAC-which endows the CSHW with markedly enhanced hydrophobicity and a higher surface potential, both of which are crucial for improving interfacial compatibility and reinforcement efficiency in composite materials.

Fluorogypsum (FG, CaSO4-II) originates during hydrofluoric acid production, has low hydration reactivity and contains high levels of free fluoride ions (F-), posing risks to soil and water quality. To enable the secure application of FG, this study evaluates sodium molybdate (Na2MoO4) as a modifier to enhance FG's hydration reactivity and immobilize F-. A novel method was employed, in which the FG paste was centrifuged at different time points prior to initial setting. The supernatants were then analyzed for calcium ions (Ca2+), molybdate ions (MoO42-), sulfate ions (SO42-), and F-, enabling real-time tracking of ion behavior and revealing the mechanism of F- immobilization. Based on these data, we provide a systematic explanation of anhydrite (AH) (CaSO4) hydration and hardening within a precipitation-dissolution equilibrium framework. Results show that MoO42- consume Ca2+ by precipitation transformation, driving the dissolution equilibrium of anhydrite to shift to the right. This induces AH to dissolve until reaching the solubility product constant (Ksp) of dihydrate gypsum (DH) (CaSO4·2H2O) without exceeding that of AH, thereby triggering DH crystallization in a positive feedback loop. Meanwhile, the formation of insoluble calcium molybdate provides heterogeneous nucleation sites that accelerate the growth of DH. With 0.7% Na2MoO4, the 28-day strength reaches 49.1 MPa, approximately 10 times that of untreated FG. Under extreme pH conditions and high temperature, this approach suppresses over 90% of F- leaching by means of chemical fixation and physical encapsulation. This modification offers a solution for stabilizing hazardous FG and converting it into safe outdoor building materials.

Silicon-based materials have emerged as prime candidates for next-generation lithium-ion battery anodes owing to their exceptional theoretical capacity. Limited by the inherent defects and high price of pure silicon, the practical application to lithium-ion battery anodes is a major challenge. Herein, porous silicon anode materials were successfully converted via magnesiothermic reduction using cost-effective and abundant fly ash cenospheres (FACs) as the precursor, and C@Si composite materials were further synthesized using phenolic resin as the carbon source to enhance electrochemical performance. The porous structure of silicon promotes lithium-ion transport, and the carbon layer provides mechanical support for silicon. The structurally optimized C@Si-FAC anode delivers exceptional performance metrics with 526 mAh center dot g- 1 reversible capacity at 50 mA center dot g- 1, sustains 346 mAh center dot g- 1 rate capability at 2000 mA center dot g- 1 and 47 % capacity retention after 100 cycles. This study provides a low-cost approach for preparing high-performance silicon-based materials for lithium-ion batteries and promotes the high-value application of solid waste.

To resolve the processing paradox in magnesium slag carbonated bricks (MSCB), where high water-to-solid (W/S) ratios compromise mechanical strength and low W/S ratios impede compaction, this study proposes a drying and static conditioning optimization strategy. This approach reduces the initial moisture content through controlled drying and subsequently regulates internal moisture redistribution via a static conditioning, thereby resolving the conflict between green body compactability and carbonation mechanical performance. Results indicate that although the moisture content decreases monotonically with prolonged drying duration, the mechanical strength exhibits a parabolic trend, initially increasing and subsequently decreasing. Sealing the green bodies with plastic film prevents moisture loss while facilitating homogeneous internal moisture redistribution. This static conditioning process minimizes the interlaminar moisture gradient to below 1%, significantly enhancing both the uniformity of CO2 diffusion and the overall degree of carbonation. Specifically, samples dried at 50 °C for 5 h and subsequently subjected to static conditioning achieved a compressive strength of 15.4 MPa and a flexural strength of 4.9 MPa, representing improvements of 19.5% and 17.6%, respectively, compared with those of the directly carbonated samples. These mechanical properties satisfy the MU15 grade criteria. Microstructural characterization shows that the static conditioning homogenizes the pore structure, promoting the formation of abundant, well-dispersed, and dense calcite and amorphous silica gel networks. The uniform distribution of these carbonation products densifies the bulk, thereby enhancing the macroscopic mechanical properties. By enhancing carbon sequestration efficiency, this technology provides a promising strategy for the resource utilization of industrial magnesium slag and simultaneous CO2 sequestration, offering valuable insights for future sustainable building material applications.

Ultra-high-performance concrete (UHPC) is highly susceptible to autogenous and drying shrinkage because of its low water-to-binder ratio, high binder content, and dense microstructure, which increases the risk of early-age cracking. In this study, a water-in-oil (W/O) emulsified edible-oil shrinkage-reducing admixture (OSRA) was prepared using a Span 80/Tween 80 compound emulsification system and incorporated into UHPC. The effects of OSRA on fresh properties, setting behavior, mechanical performance, shrinkage, wettability, water transport, internal moisture evolution, hydration kinetics, and microstructure were systematically investigated. The results showed that OSRA markedly reduced both autogenous and drying shrinkage. At a dosage of 4%, the reductions in 7 d autogenous shrinkage and 28 d drying shrinkage reached 68% and 60%, respectively. However, the high OSRA dosage caused evident strength loss and local microstructural loosening. In comparison, 2% OSRA provided a better balance between shrinkage mitigation and mechanical-property retention, with 28 d compressive and flexural strengths maintained at 90.44% and 86.30% of the reference values, respectively. Contact angle, capillary water absorption, and low-field nuclear magnetic resonance results indicated that the shrinkage-reducing effect of OSRA was mainly associated with enhanced hydrophobicity, restricted continuous liquid-water transport, and delayed internal moisture dissipation. Hydration heat, XRD, TG-DTG, pore structure, and SEM analyses further confirmed that OSRA did not alter the main hydration products of UHPC, but regulated early hydration kinetics, pore-size redistribution, and local interfacial structure in a dosage-dependent manner. These findings suggest that W/O-type emulsified edible oil, when properly dosed to balance shrinkage mitigation and mechanical-property retention,can serve as a promising bio-based shrinkage-reducing admixture for UHPC through a hydrophobic regulation mechanism.

The massive accumulation of fluorogypsum (FG) poses severe environmental challenges. To address the limitations of previous single-factor studies, this research employed the Box-Behnken design and response surface methodology (BBD-RSM) to investigate the interactive effects of FG, ground granulated blast-furnace slag (GGBS), and sodium sulfate (Na₂SO₄) on the compressive strength of a novel solid waste-based cementitious material. Analysis of variance confirmed the high fitting accuracy of the established quadratic regression model. Results indicated that the significance of factors on compressive strength ranks as: GGBS > FG > Na₂SO₄. The optimal mix proportion for maximizing compressive strength was determined as 65.39% FG, 15% GGBS, 14.61% fly ash (FA), and 5% ordinary Portland cement (OPC), with an external addition of 1.47% Na₂SO₄. Under this formulation, the measured 28-day compressive strength reached 36.51 MPa, yielding a relative error of only 1.4% compared to the predicted value. This study provides robust theoretical guidance for the large-scale application of FG in green building materials.

Alkali-activated slag-based ultra-high-performance concrete (AAS-UHPC) offers a low-carbon alternative to Portland cement-based UHPC, but its performance is highly dependent on Na2O dosage. The dosage threshold at which beneficial activation turns into deterioration remains unclear. This study investigates the effects of Na2O dosage on the performance, microstructure, durability, and sustainability of slag–silica fume-based AAS-UHPC. Mixtures with 7–11% Na2O by binder mass were prepared and tested for fresh properties, setting behavior, mechanical strength, drying shrinkage, sulfate resistance, and sulfuric acid resistance. NMR, XRD, FTIR, SEM, and SEM-EDS were used to characterize pore structure and reaction products, while life-cycle assessment and cost analysis were conducted to evaluate environmental and economic feasibility. Results show that increasing Na2O from 7% to 9% improved workability, accelerated setting, refined pore structure, and enhanced strength. The 9% Na2O mixture achieved the highest 28 d compressive and flexural strengths of 148.72MPa and 25.77MPa, respectively, with the lowest porosity of 3.71%. However, 10–11% Na2O was associated with less favorable microstructural development, pore coarsening, increased shrinkage, microcracking, and reduced durability. The 11% Na2O mixture displayed visible cracking, increased porosity of 6.12%, and a pronounced reduction in 28 d compressive strength to 100.31MPa, indicating severe microstructural deterioration and alkali-associated volume instability under excessive alkalinity. Overall, 8–9% Na2O provides the most balanced design range, integrating mechanical performance, durability, dimensional stability, carbon efficiency, and cost-effectiveness.

This study develops an eco-friendly 3D printing concrete (3DPC) system fabricated entirely from industrial by-products and elucidates the mechanism by which molybdenum tailings (MT) replacement for quartz sand (SS) regulates system performance. The formulation builds upon a fluorogypsum-based binder previously optimized by our research team. A single-variable approach, varying the MT replacement ratio from 0% to 100%, was employed to systematically evaluate its impact on fresh rheological behavior, printability, and hardened mechanical properties. Results indicate that, compared to SS, the irregular geometry and high water absorption of MT significantly enhance the yield stress and thixotropy of the paste, thereby remarkably reducing the structural deformation during printing. Despite a slight reduction in early-age strength, MT incorporation significantly bolsters long-term mechanical performance. Microscopic analysis reveals a dual-effect mechanism of MT: initially, its high water absorption reduces the effective water-to-binder ratio, lowering internal humidity and retarding early hydration; subsequently, the released adsorbed water exerts an “internal curing” effect. This phenomenon, combined with the surface nucleation activity of MT, substantially promotes long-term mechanical performance. By 60 days, the interfacial transition zone (ITZ) is significantly refined, as evidenced by reduced thickness and lower overall porosity. Replacing SS entirely with MT reduces the material cost per cubic meter by 29.8%. This study achieves a sustainable design for both binders and aggregates while revealing the reinforcement mechanism of MT in solid waste matrices, providing a theoretical foundation for the high-value utilization of molybdenum tailings.

The development of Low Calcium Carbonatable Binder (LCCB) with high carbonation performance is crucial for mitigating the environmental impact of the cement industry. This study aims to elucidate the mechanism by which tungsten (W) doping enhances the carbonation activity and mechanical properties of LCCB. Employing a combined approach of Density Functional Theory (DFT) computational predictions and experimental validation, we systematically investigated the doping behavior and its multi-scale effects. The results indicate that W6 + preferentially substitute for Si sites in the alpha-CS phase, a process driven by negative formation energy and compatible electronic structures. This substitution induces significant structural distortion in the adjacent Ca-O polyhedra, characterized by elongated bond lengths and a reduced coordination number, which weakens the crystal lattice and facilitates Ca2+ ion migration. At an optimal doping content of 4.6 wt%, this atomic-scale activation translates into accelerated carbonation reaction kinetics, as evidenced by a higher exothermic peak temperature and a shorter time to reach the peak. Consequently, the yield of calcite increases substantially, leading to a remarkable 75.8% improvement in the 8 h compressive strength compared to the undoped sample. This work provides fundamental guidance for the performance-oriented design of advanced carbonatable binders materials through ion doping.